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Antepartum Testing and Monitoring

The primary goals of antepartum testing and monitoring are to assess fetal well-being, identify treatable situations that may cause complications, and evaluate for chromosomal abnormalities. Antepartum tests for aneuploidy are typically performed in the 1st and 2nd trimesters. These tests are divided into screening tests Screening tests Screening tests are used to identify people in the early stages of a disease and enable early intervention with the goal of reducing morbidity and mortality. Epidemiological Values of Diagnostic Tests (which include cell-free DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure testing, serum analyte Analyte The molecule of interest (antigen) Immunoassays testing, and nuchal translucency Nuchal translucency A prenatal ultrasonography measurement of the soft tissue behind the fetal neck. Either the translucent area below the skin in the back of the fetal neck (nuchal translucency) or the distance between occipital bone to the outer skin line (nuchal fold) is measured. Obstetric Imaging measurements), and diagnostic tests Diagnostic tests Diagnostic tests are important aspects in making a diagnosis. Some of the most important epidemiological values of diagnostic tests include sensitivity and specificity, false positives and false negatives, positive and negative predictive values, likelihood ratios, and pre-test and post-test probabilities. Epidemiological Values of Diagnostic Tests, which provide a definitive diagnosis of aneuploidy and include chorionic villus sampling (CVS) and amniocentesis Amniocentesis Percutaneous transabdominal puncture of the uterus during pregnancy to obtain amniotic fluid. It is commonly used for fetal karyotype determination in order to diagnose abnormal fetal conditions. Polyhydramnios. Antepartum monitoring is done in the 2nd and 3rd trimesters to evaluate fetal well-being and assess the risk of fetal death. Antepartum monitoring tests include continuous cardiotocography (i.e., fetal heart rate Heart rate The number of times the heart ventricles contract per unit of time, usually per minute. Cardiac Physiology tracings), the non-stress and contraction stress tests (NST and CST, respectively), the fetal biophysical profile Biophysical Profile Obstetric Imaging (BPP), and umbilical artery Umbilical artery Specialized arterial vessels in the umbilical cord. They carry waste and deoxygenated blood from the fetus to the mother via the placenta. In humans, there are usually two umbilical arteries but sometimes one. Prenatal and Postnatal Physiology of the Neonate Doppler Doppler Ultrasonography applying the doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. Ultrasound (Sonography) studies.

Last updated: Jul 18, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Overview

Definition

Antepartum testing

  • 2 categories:
    • Screening tests Screening tests Screening tests are used to identify people in the early stages of a disease and enable early intervention with the goal of reducing morbidity and mortality. Epidemiological Values of Diagnostic Tests: noninvasive tests, including maternal blood work and imaging 
    • Diagnostic tests Diagnostic tests Diagnostic tests are important aspects in making a diagnosis. Some of the most important epidemiological values of diagnostic tests include sensitivity and specificity, false positives and false negatives, positive and negative predictive values, likelihood ratios, and pre-test and post-test probabilities. Epidemiological Values of Diagnostic Tests: invasive tests that involve obtaining a sample of material from inside the womb that contains fetal DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure
  • Should be offered to all pregnant women to assess the risk for genetic conditions (some may decline)

Antepartum monitoring 

  • Refers to a variety of tests used to evaluate fetal well-being and assess the risk of intrauterine fetal hypoxic injury or death
  • The most common (and most clinically important) monitoring tests include:
    • Continuous cardiotocography (also known simply as “continuous fetal monitoring”)
    • Non-stress test (NST)
    • Contraction stress test (CST)
    • Biophysical profile Biophysical Profile Obstetric Imaging (BPP)
    • Umbilical artery Umbilical artery Specialized arterial vessels in the umbilical cord. They carry waste and deoxygenated blood from the fetus to the mother via the placenta. In humans, there are usually two umbilical arteries but sometimes one. Prenatal and Postnatal Physiology of the Neonate Doppler Doppler Ultrasonography applying the doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. Ultrasound (Sonography)

General indications

There are many indications for fetal monitoring and/or screening Screening Preoperative Care, including: 

Maternal indications

  • Preterm labor Labor Labor is the normal physiologic process defined as uterine contractions resulting in dilatation and effacement of the cervix, which culminates in expulsion of the fetus and the products of conception. Normal and Abnormal Labor and/or preterm premature Premature Childbirth before 37 weeks of pregnancy (259 days from the first day of the mother’s last menstrual period, or 245 days after fertilization). Necrotizing Enterocolitis rupture of membranes (PPROM)
  • Prior fetal death
  • Preexisting or gestational diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus
  • Chronic or pregnancy-related hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension (e.g., preeclampsia Preeclampsia A complication of pregnancy, characterized by a complex of symptoms including maternal hypertension and proteinuria with or without pathological edema. Symptoms may range between mild and severe. Pre-eclampsia usually occurs after the 20th week of gestation, but may develop before this time in the presence of trophoblastic disease. Hypertensive Pregnancy Disorders)
  • Alloimmunization to RBC antigens
  • Intrahepatic cholestasis of pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care ( ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP))
  • Other preexisting medical conditions, including (but not limited to):
    • Systemic lupus erythematosus Systemic lupus erythematosus Systemic lupus erythematosus (SLE) is a chronic autoimmune, inflammatory condition that causes immune-complex deposition in organs, resulting in systemic manifestations. Women, particularly those of African American descent, are more commonly affected. Systemic Lupus Erythematosus ( SLE SLE Systemic lupus erythematosus (SLE) is a chronic autoimmune, inflammatory condition that causes immune-complex deposition in organs, resulting in systemic manifestations. Women, particularly those of African American descent, are more commonly affected. Systemic Lupus Erythematosus) and/or chronic renal disease
    • Antiphospholipid syndrome Antiphospholipid syndrome Antiphospholipid syndrome (APLS) is an acquired autoimmune disorder characterized by the persistent presence of antiphospholipid antibodies, which create a hypercoagulable state. These antibodies are most commonly discovered during a workup for a thrombotic event or recurrent pregnancy loss, which are the 2 most common clinical manifestations. Antiphospholipid Syndrome
    • Maternal cyanotic heart disease
    • Hemoglobinopathies Hemoglobinopathies A group of inherited disorders characterized by structural alterations within the hemoglobin molecule. Anemia: Overview and Types (e.g., sickle cell disease Sickle cell disease Sickle cell disease (SCD) is a group of genetic disorders in which an abnormal Hb molecule (HbS) transforms RBCs into sickle-shaped cells, resulting in chronic anemia, vasoocclusive episodes, pain, and organ damage. Sickle Cell Disease)

Fetal indications

  • Multiple gestations (e.g., twin pregnancies)
  • Postterm pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care
  • Fetal growth restriction Fetal growth restriction Fetal growth restriction (FGR), also known as intrauterine fetal growth restriction (IUGR), is an estimated fetal weight (EFW) or abdominal circumference < 10th percentile for gestational age. The term small for gestational age (SGA) is sometimes erroneously used interchangeably with FGR. Fetal Growth Restriction
  • Oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of < 2 cm in the 2nd or 3rd trimester. Oligohydramnios 
  • Decreased fetal movement (detected by mother)

Screening Tests

Routine pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care laboratory and imaging studies

All pregnant women should have certain screening Screening Preoperative Care laboratory tests and imaging studies done at different points during the pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care, including:

At the 1st OB appointment:

  • Screening Screening Preoperative Care for anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types: CBC
  • Screening Screening Preoperative Care for maternal–fetal blood incompatibility: blood type and screen 
  • Screening Screening Preoperative Care for infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease:
    • Urinalysis Urinalysis Examination of urine by chemical, physical, or microscopic means. Routine urinalysis usually includes performing chemical screening tests, determining specific gravity, observing any unusual color or odor, screening for bacteriuria, and examining the sediment microscopically. Urinary Tract Infections (UTIs) in Children
    • Rubella Rubella An acute infectious disease caused by the rubella virus. The virus enters the respiratory tract via airborne droplet and spreads to the lymphatic system. Rubella Virus immunity status
    • HIV HIV Anti-HIV Drugs
    • Hepatitis B Hepatitis B Hepatitis B virus (HBV) is a partially double-stranded DNA virus, which belongs to the Orthohepadnavirus genus and the Hepadnaviridae family. Most individuals with acute HBV infection are asymptomatic or have mild, self-limiting symptoms. Chronic infection can be asymptomatic or create hepatic inflammation, leading to liver cirrhosis and hepatocellular carcinoma (HCC). Hepatitis B Virus surface antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination 
    • Rapid plasma reagin test Rapid plasma reagin test Treponema for syphilis Syphilis Syphilis is a bacterial infection caused by the spirochete Treponema pallidum pallidum (T. p. pallidum), which is usually spread through sexual contact. Syphilis has 4 clinical stages: primary, secondary, latent, and tertiary. Syphilis
    • Gonorrhea Gonorrhea Gonorrhea is a sexually transmitted infection (STI) caused by the gram-negative bacteria Neisseria gonorrhoeae (N. gonorrhoeae). Gonorrhea may be asymptomatic but commonly manifests as cervicitis or urethritis with less common presentations such as proctitis, conjunctivitis, or pharyngitis. Gonorrhea and chlamydia Chlamydia Chlamydiae are obligate intracellular gram-negative bacteria. They lack a peptidoglycan layer and are best visualized using Giemsa stain. The family of Chlamydiaceae comprises 3 pathogens that can infect humans: Chlamydia trachomatis, Chlamydia psittaci, and Chlamydia pneumoniae. Chlamydia testing
  • Screening Screening Preoperative Care for cancer: Pap smear Pap smear Cytological preparation of cells collected from a mucosal surface and stained with Papanicolaou stain. Cervical Cancer Screening (only if due for routine Pap screening Screening Preoperative Care)
  • Screening Screening Preoperative Care for inherited diseases: based on ethnicity (e.g., hemoglobinopathies Hemoglobinopathies A group of inherited disorders characterized by structural alterations within the hemoglobin molecule. Anemia: Overview and Types, cystic fibrosis Cystic fibrosis Cystic fibrosis is an autosomal recessive disorder caused by mutations in the gene CFTR. The mutations lead to dysfunction of chloride channels, which results in hyperviscous mucus and the accumulation of secretions. Common presentations include chronic respiratory infections, failure to thrive, and pancreatic insufficiency. Cystic Fibrosis)
  • Screening Screening Preoperative Care for aneuploidy (e.g., trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 21) based on woman’s desire

Other testing

  • Screening Screening Preoperative Care for anatomic issues: anatomic ultrasonography at 18‒22 weeks of gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care (wga), which includes assessment of the fetus, placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity, and uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy/ cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy
  • Screening Screening Preoperative Care for gestational diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus: 1-hour glucose tolerance test Glucose Tolerance Test A test to determine the ability of an individual to maintain homeostasis of blood glucose. It includes measuring blood glucose levels in a fasting state, and at prescribed intervals before and after oral glucose intake (75 or 100 g) or intravenous infusion (0. 5 g/kg). Physical Examination of the Newborn (GTT) at 24‒28 wga
  • Repeat screening Screening Preoperative Care for anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types: CBC is usually repeated with the GTT.
  • Screening Screening Preoperative Care for group B streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus ( GBS GBS An acute inflammatory autoimmune neuritis caused by t cell- mediated cellular immune response directed towards peripheral myelin. Demyelination occurs in peripheral nerves and nerve roots. The process is often preceded by a viral or bacterial infection, surgery, immunization, lymphoma, or exposure to toxins. Common clinical manifestations include progressive weakness, loss of sensation, and loss of deep tendon reflexes. Weakness of respiratory muscles and autonomic dysfunction may occur. Polyneuropathy) colonization Colonization Bacteriology: GBS GBS An acute inflammatory autoimmune neuritis caused by t cell- mediated cellular immune response directed towards peripheral myelin. Demyelination occurs in peripheral nerves and nerve roots. The process is often preceded by a viral or bacterial infection, surgery, immunization, lymphoma, or exposure to toxins. Common clinical manifestations include progressive weakness, loss of sensation, and loss of deep tendon reflexes. Weakness of respiratory muscles and autonomic dysfunction may occur. Polyneuropathy rectovaginal culture at 35‒37 wga 
  • Screening Screening Preoperative Care for malposition: bedside ultrasonography Bedside Ultrasonography ACES and RUSH: Resuscitation Ultrasound Protocols to check fetal presentation Fetal presentation Fetal presentation describes which part of the fetus will enter through the cervix first, while position is the orientation of the fetus compared to the maternal bony pelvis. Presentations include vertex (the fetal occiput will present through the cervix first), face, brow, shoulder, and breech. Fetal Malpresentation and Malposition (vertex/head down or breech/buttocks down) around 35 wga

Screening Screening Preoperative Care for fetal aneuploidy

Overview

  • Screening Screening Preoperative Care (noninvasive tests) indirectly assesses the risk of fetal aneuploidy by testing maternal blood and/or by performing ultrasonography.
    • Multiple options available: combinations of different serum analytes and/or ultrasonography
    • Some tests can be performed only at specific gestational ages.
    • Chromosomal abnormality detection rates vary.
  • Results:
    • Need to be confirmed by diagnostic testing for definitive diagnosis
    • Influenced by maternal age
  • The most commonly used screening tests Screening tests Screening tests are used to identify people in the early stages of a disease and enable early intervention with the goal of reducing morbidity and mortality. Epidemiological Values of Diagnostic Tests are:
    • Cell-free fetal DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure testing (cf-DNA)
    • 1st-trimester testing
    • Quadruple test
    • Integrated testing

Cell-free fetal DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure testing

  • Also known as noninvasive prenatal screening Screening Preoperative Care (NIPS) or noninvasive prenatal testing (NIPT)
  • Performed anytime after 10 wga
  • How it works: 
    • Apoptosis Apoptosis A regulated cell death mechanism characterized by distinctive morphologic changes in the nucleus and cytoplasm, including the endonucleolytic cleavage of genomic DNA, at regularly spaced, internucleosomal sites, I.e., DNA fragmentation. It is genetically-programmed and serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth. Ischemic Cell Damage of placental cells (which contain fetal DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure) release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology fragments of fetal DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure into maternal serum.
    • These cell-free fetal DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure fragments (usually about 50‒200 base pairs) can be isolated from maternal blood for testing.
    • Amount of DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure from each fetal chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics is determined → elevated proportions of genetic material from 1 chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics strongly suggests triploidy
  • Has the highest sensitivity for detecting chromosomal abnormalities of all the screening tests Screening tests Screening tests are used to identify people in the early stages of a disease and enable early intervention with the goal of reducing morbidity and mortality. Epidemiological Values of Diagnostic Tests:
    • Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 21: > 99% 
    • Trisomy 18 Trisomy 18 Edwards syndrome, or trisomy 18, is a genetic syndrome caused by the presence of an extra chromosome 18. The extra chromosome is either from 3 full copies of chromosome 18 or an additional segment of chromosome 18. As the 2nd most common trisomy, Edwards syndrome is seen in 1 out of every 5,500 live births. Edwards Syndrome (Trisomy 18): 98%
    • Trisomy 13 Trisomy 13 Trisomy 13, or Patau syndrome, is a genetic syndrome caused by the presence of 3 copies of chromosome 13. As the 3rd most common trisomy, Patau syndrome has an incidence of 1 in 10,000 live births. Most cases of Patau syndrome are diagnosed prenatally by maternal screening and ultrasound. More than half of the pregnancies result in spontaneous abortions. Patau Syndrome (Trisomy 13): 96%
  • Low cumulative false positive False positive An FP test result indicates that a person has the disease when they do not. Epidemiological Values of Diagnostic Tests rate: approximately 0.1%
  • Still considered a screening Screening Preoperative Care test owing to lower positive predictive values, especially in younger women, in whom aneuploidies are much less common:
  • Diagnostic testing should be used to confirm diagnosis, especially in younger patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship.
  • Note that fetal sex Sex The totality of characteristics of reproductive structure, functions, phenotype, and genotype, differentiating the male from the female organism. Gender Dysphoria can be determined using cell-free fetal DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure testing.

1st-trimester screening Screening Preoperative Care for aneuploidy

  • Often called combined testing
  • Performed around 12 wga (range, 10–13 ⁶⁄₇ wga) 
  • Primarily screens for trisomies 21, 18, and 13
  • Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 21 detection rate: 85%
  • Measures 3 markers:
    • Maternal serum β-hCG
    • Maternal serum pregnancy-associated plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products protein A (PAPP-A)
    • Ultrasound measurement of the nuchal translucency Nuchal translucency A prenatal ultrasonography measurement of the soft tissue behind the fetal neck. Either the translucent area below the skin in the back of the fetal neck (nuchal translucency) or the distance between occipital bone to the outer skin line (nuchal fold) is measured. Obstetric Imaging, a hypoechoic Hypoechoic A structure that produces a low-amplitude echo (darker grays) Ultrasound (Sonography) space in the posterior aspect of the fetal neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess
Table: 1st-trimester screening Screening Preoperative Care test results associated with common aneuploidies
Condition hCG PAPP-A Nuchal translucency Nuchal translucency A prenatal ultrasonography measurement of the soft tissue behind the fetal neck. Either the translucent area below the skin in the back of the fetal neck (nuchal translucency) or the distance between occipital bone to the outer skin line (nuchal fold) is measured. Obstetric Imaging
Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 21 ↓↓ ↑↑
Trisomy 18 Trisomy 18 Edwards syndrome, or trisomy 18, is a genetic syndrome caused by the presence of an extra chromosome 18. The extra chromosome is either from 3 full copies of chromosome 18 or an additional segment of chromosome 18. As the 2nd most common trisomy, Edwards syndrome is seen in 1 out of every 5,500 live births. Edwards Syndrome (Trisomy 18) ↓↓ ↓↓ ↑↑
Trisomy 13 Trisomy 13 Trisomy 13, or Patau syndrome, is a genetic syndrome caused by the presence of 3 copies of chromosome 13. As the 3rd most common trisomy, Patau syndrome has an incidence of 1 in 10,000 live births. Most cases of Patau syndrome are diagnosed prenatally by maternal screening and ultrasound. More than half of the pregnancies result in spontaneous abortions. Patau Syndrome (Trisomy 13) ↓↓

Quadruple screen ( quad screen Quad Screen Prenatal Care)

  • Done in the 2nd trimester between 15 and 22 ⁶⁄₇ wga
  • Screens for trisomies 21 and 18
  • Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 21 detection rate: 80%
  • Uses serum markers, maternal age, weight, race, and presence of pregestational diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus to calculate a risk estimate
  • Measures 4 serum markers:
    • Maternal serum β-hCG
    • Maternal serum alpha fetoprotein Alpha fetoprotein The first alpha-globulins to appear in mammalian sera during fetal development and the dominant serum proteins in early embryonic life. Testicular Cancer (MS-AFP)
    • Unconjugated estriol Estriol A hydroxylated metabolite of estradiol or estrogen that has a hydroxyl group at C3, 16-alpha, and 17-beta position. Estriol is a major urinary estrogen. During pregnancy, a large amount of estriol is produced by the placenta. Isomers with inversion of the hydroxyl group or groups are called epiestriol. Noncontraceptive Estrogen and Progestins (uE3)
    • Inhibin A Inhibin A Glycoproteins that inhibit pituitary follicle stimulating hormone secretion. Inhibins are secreted by the sertoli cells of the testes, the granulosa cells of the ovarian follicles, the placenta, and other tissues. Inhibins and activins are modulators of follicle stimulating hormone secretions; both groups belong to the TGF-beta superfamily, as the transforming growth factor beta. Inhibins consist of a disulfide-linked heterodimer with a unique alpha linked to either a beta a or a beta B subunit to form inhibin a or inhibin b, respectively. Menstrual Cycle 
  • Does not require ultrasonography or nuchal translucency Nuchal translucency A prenatal ultrasonography measurement of the soft tissue behind the fetal neck. Either the translucent area below the skin in the back of the fetal neck (nuchal translucency) or the distance between occipital bone to the outer skin line (nuchal fold) is measured. Obstetric Imaging measurement
Table: Quadruple screening Screening Preoperative Care test results associated with trisomies 21 and 18
Condition hCG AFP AFP The first alpha-globulins to appear in mammalian sera during fetal development and the dominant serum proteins in early embryonic life. Hepatocellular Carcinoma (HCC) and Liver Metastases Estriol Estriol A hydroxylated metabolite of estradiol or estrogen that has a hydroxyl group at C3, 16-alpha, and 17-beta position. Estriol is a major urinary estrogen. During pregnancy, a large amount of estriol is produced by the placenta. Isomers with inversion of the hydroxyl group or groups are called epiestriol. Noncontraceptive Estrogen and Progestins Inhibin A Inhibin A Glycoproteins that inhibit pituitary follicle stimulating hormone secretion. Inhibins are secreted by the sertoli cells of the testes, the granulosa cells of the ovarian follicles, the placenta, and other tissues. Inhibins and activins are modulators of follicle stimulating hormone secretions; both groups belong to the TGF-beta superfamily, as the transforming growth factor beta. Inhibins consist of a disulfide-linked heterodimer with a unique alpha linked to either a beta a or a beta B subunit to form inhibin a or inhibin b, respectively. Menstrual Cycle
Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 21
Trisomy 18 Trisomy 18 Edwards syndrome, or trisomy 18, is a genetic syndrome caused by the presence of an extra chromosome 18. The extra chromosome is either from 3 full copies of chromosome 18 or an additional segment of chromosome 18. As the 2nd most common trisomy, Edwards syndrome is seen in 1 out of every 5,500 live births. Edwards Syndrome (Trisomy 18) ↓↓ ↓↓

Integrated testing:

  • Combines results from 1st- and 2nd-trimester testing
  • Results are used to calculate a single patient-specific risk for aneuploidies.
  • Detection rate for trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 21: 96%
  • Variations:
    • Full integrated testing: All serum analytes and nuchal translucency Nuchal translucency A prenatal ultrasonography measurement of the soft tissue behind the fetal neck. Either the translucent area below the skin in the back of the fetal neck (nuchal translucency) or the distance between occipital bone to the outer skin line (nuchal fold) is measured. Obstetric Imaging are assessed.
    • Serum integrated screening Screening Preoperative Care: Only serum is analyzed (no nuchal translucency Nuchal translucency A prenatal ultrasonography measurement of the soft tissue behind the fetal neck. Either the translucent area below the skin in the back of the fetal neck (nuchal translucency) or the distance between occipital bone to the outer skin line (nuchal fold) is measured. Obstetric Imaging assessment).
    • Sequential Sequential Computed Tomography (CT) screening Screening Preoperative Care: Initial risk assessment Risk assessment The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. Preoperative Care is provided after 1st-trimester tests and then revised after 2nd-trimester tests.

Diagnostic Tests

Diagnostic testing is invasive and involves sampling the chorionic villi Chorionic villi Threadlike vascular projections of the chorion. Chorionic villi may be free or embedded within the decidua forming the site for exchange of substances between fetal and maternal blood (placenta). Placenta, Umbilical Cord, and Amniotic Cavity or amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity for fetal tissue that can be used directly for genetic testing Genetic Testing Detection of a mutation; genotype; karyotype; or specific alleles associated with genetic traits, heritable diseases, or predisposition to a disease, or that may lead to the disease in descendants. It includes prenatal genetic testing. Myotonic Dystrophies.

Chorionic villus sampling (CVS)

  • Procedure: 
    • Placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity is biopsied under real-time ultrasound guidance.
    • Sample is tested for genetic anomalies (e.g., karyotype Karyotype The full set of chromosomes presented as a systematized array of metaphase chromosomes from a photomicrograph of a single cell nucleus arranged in pairs in descending order of size and according to the position of the centromere. Congenital Malformations of the Female Reproductive System).
    • Can be performed transabdominally or transcervically
  • Timing: done between 10 and 13 wga
  • Indications:
    • Confirming abnormal screen results 
    • Congenital Congenital Chorioretinitis anomaly seen on 1st-trimester ultrasound examination
    • Previous pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care with a chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics abnormality or genetic disorder
    • Known genetic anomalies (e.g., balanced translocation) in one of the parents
Chorionic villus sampling

Illustration representing the chorionic villus sampling (CVS) procedure

Image by Lecturio.

Amniocentesis Amniocentesis Percutaneous transabdominal puncture of the uterus during pregnancy to obtain amniotic fluid. It is commonly used for fetal karyotype determination in order to diagnose abnormal fetal conditions. Polyhydramnios

  • Procedure:
    • Under ultrasound guidance, a long needle is used to obtain a sample of amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity for testing.
    • Done transabdominally
  • Timing: any time after 15 wga
  • Amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity obtained can also be used for tests other than genetics Genetics Genetics is the study of genes and their functions and behaviors. Basic Terms of Genetics.
  • Indications:
    • Confirming abnormal screen results
    • Fetal evaluation for infection
    • Fetal structural anomalies
    • Concern for maternal–fetal blood-type incompatibility
    • Assessment of fetal lung maturity (previously a common indication, now rarely done)
Amniocentesis

Illustration representing the amniocentesis Amniocentesis Percutaneous transabdominal puncture of the uterus during pregnancy to obtain amniotic fluid. It is commonly used for fetal karyotype determination in order to diagnose abnormal fetal conditions. Polyhydramnios procedure

Image by Lecturio.

Relative contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation

The only relative contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation for both procedures include:

  • Maternal alloimmunization
  • Poorly controlled maternal infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease with risk for vertical transmission Vertical transmission The transmission of infectious disease or pathogens from one generation to another. It includes transmission in utero or intrapartum by exposure to blood and secretions, and postpartum exposure via breastfeeding. Congenital TORCH Infections (e.g., HIV HIV Anti-HIV Drugs and hepatitis B Hepatitis B Hepatitis B virus (HBV) is a partially double-stranded DNA virus, which belongs to the Orthohepadnavirus genus and the Hepadnaviridae family. Most individuals with acute HBV infection are asymptomatic or have mild, self-limiting symptoms. Chronic infection can be asymptomatic or create hepatic inflammation, leading to liver cirrhosis and hepatocellular carcinoma (HCC). Hepatitis B Virus)

Complications

Potential complications are similar for both CVS and amniocentesis Amniocentesis Percutaneous transabdominal puncture of the uterus during pregnancy to obtain amniotic fluid. It is commonly used for fetal karyotype determination in order to diagnose abnormal fetal conditions. Polyhydramnios and include: 

  • Fetal loss (risk is approximately 0.7% with CVS and approximately 0.2% with amniocentesis Amniocentesis Percutaneous transabdominal puncture of the uterus during pregnancy to obtain amniotic fluid. It is commonly used for fetal karyotype determination in order to diagnose abnormal fetal conditions. Polyhydramnios)
  • Fetal injury
  • Infection
  • Vertical transmission Vertical transmission The transmission of infectious disease or pathogens from one generation to another. It includes transmission in utero or intrapartum by exposure to blood and secretions, and postpartum exposure via breastfeeding. Congenital TORCH Infections of maternal infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease
  • PPROM in amniocentesis Amniocentesis Percutaneous transabdominal puncture of the uterus during pregnancy to obtain amniotic fluid. It is commonly used for fetal karyotype determination in order to diagnose abnormal fetal conditions. Polyhydramnios done later in pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care

Cardiotocography (i.e., Fetal Monitoring) Tests

Cardiotocography is used to monitor the fetal heart rate Heart rate The number of times the heart ventricles contract per unit of time, usually per minute. Cardiac Physiology (FHR) and contractions plotted over real time, usually via abdominal ultrasonography and pressure transducers, respectively. Fetal heart rate Heart rate The number of times the heart ventricles contract per unit of time, usually per minute. Cardiac Physiology is recorded in the top panel and contractions in the lower panel of the tracing.

Cardiotocography tracing characteristics

There are 5 major components that should be evaluated when interpreting a cardiotocography tracing:

  • FHR baseline: the average number of beats per minute
    • Normal: 110‒160/min
    • Tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children: > 160/min when sustained ≥ 10 minutes
    • Bradycardia Bradycardia Bradyarrhythmia is a rhythm in which the heart rate is less than 60/min. Bradyarrhythmia can be physiologic, without symptoms or hemodynamic change. Pathologic bradyarrhythmia results in reduced cardiac output and hemodynamic instability causing syncope, dizziness, or dyspnea. Bradyarrhythmias: < 100/min when sustained ≥ 10 minutes
  • FHR variability: how much the FHR changes from beat to beat above or below baseline (i.e., how “bumpy” the line is)
    • Moderate variability (normal): 6‒25/min
      • The fetal heart has minimal ability to adjust stroke volume Stroke volume The amount of blood pumped out of the heart per beat, not to be confused with cardiac output (volume/time). It is calculated as the difference between the end-diastolic volume and the end-systolic volume. Cardiac Cycle, so must adjust HR in order to adjust cardiac output Cardiac output The volume of blood passing through the heart per unit of time. It is usually expressed as liters (volume) per minute so as not to be confused with stroke volume (volume per beat). Cardiac Mechanics.
      • Rapid adjustments to FHR represent a functioning CNS → reliably predicts the absence of hypoxic damage
    • Marked variability: > 25/min (nonspecific finding)
    • Minimal variability: < 5/min
      • Represents a fairly constant FHR owing to CNS depression
      • May be seen normally during fetal sleep Sleep A readily reversible suspension of sensorimotor interaction with the environment, usually associated with recumbency and immobility. Physiology of Sleep cycles or after maternal opiate use (often prescribed in early labor Labor Labor is the normal physiologic process defined as uterine contractions resulting in dilatation and effacement of the cervix, which culminates in expulsion of the fetus and the products of conception. Normal and Abnormal Labor)
      • May be due to CNS hypoxic injury/ acidemia Acidemia Respiratory Acidosis
    • Absent variability: no change in FHR (flat line) 
  • FHR accelerations: brief ↑ in FHR
    • > 32 weeks: defined as occasional ↑ in FHR by ≥ 15/min for 15 seconds
    • < 32 weeks: defined as occasional ↑ in FHR by ≥ 10/min for 10 seconds
  • FHR decelerations: brief ↓ in FHR
    • Early (nonpathologic): 
      • Slower decline and return to baseline (U-shaped)
      • Nadir mirrors the contraction peak.
      • A normal vagal response due to head compression Compression Blunt Chest Trauma
      • No intervention needed
    • Variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables (sometimes a concern): 
      • Sharp decline with rapid return to baseline (V-shaped)
      • Due to cord compression Compression Blunt Chest Trauma
      • Interpretation depends on the clinical context
    • Late (always pathologic): 
      • Slower decline and return to baseline (U-shaped)
      • Nadir follows the peak of the contraction.
      • Due to uteroplacental insufficiency Uteroplacental Insufficiency Uteroplacental insufficiency may be acute or chronic and refers to the inability of the placenta to deliver a sufficient supply of O2 and nutrients to the fetus Placental Abnormalities
      • Always requires intervention
  • Contractions:
    • Normal: 2‒5 contractions in 10 minutes during labor Labor Labor is the normal physiologic process defined as uterine contractions resulting in dilatation and effacement of the cervix, which culminates in expulsion of the fetus and the products of conception. Normal and Abnormal Labor
    • Tachysystole: > 5 contractions in 10 minutes
    • External pressure transducers versus intrauterine pressure catheters (IUPCs):
      • External pressure transducers: only show the relative pressure within the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy at a given time
      • IUPC: a catheter inserted into the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy during labor Labor Labor is the normal physiologic process defined as uterine contractions resulting in dilatation and effacement of the cervix, which culminates in expulsion of the fetus and the products of conception. Normal and Abnormal Labor (after rupture of membranes) to measure the actual numeric pressure generated by the contractions; measured in Montevideo units (MVUs)

Interpreting cardiotocography tracings

Characteristics of a continuous FHR tracing are assessed periodically and used to classify tracings into 1 of 3 categories. These categories provide some prognostic information on the current status of fetal well-being and can help guide management.

Category I: normal

  • All of the following characteristics must be present:
    • FHR: 110‒160/min 
    • Moderate variability 
    • No variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables or late decelerations 
  • Early decelerations may be present or absent
  • Interpretation: minimal chance of fetal acidemia Acidemia Respiratory Acidosis/hypoxic injury at this point in time
  • Management: observation/continue current course of action
Category i fetal heart rate tracing

Category I (normal) fetal heart rate Heart rate The number of times the heart ventricles contract per unit of time, usually per minute. Cardiac Physiology tracing
An FHR baseline of 150/min, moderate variability, several accelerations, and no decelerations are seen. Three contractions are shown; if these contractions were measured using an intrauterine pressure catheter, they each reach approximately 60 Montevideo units (MVUs), for a total of 180 MVUs in the 8 minutes shown. Based on this pattern, there would likely be a 4th contraction near the 10-minute mark, making this contraction pattern adequate (defined as > 200 MVUs per 10 minutes) to induce cervical change.

Image by Lecturio.

Category II: indeterminate

  • Everything that is not category I or III
  • This category includes:
    • A normal FHR (110‒160/min) with variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables or late decelerations
    • A normal FHR (110‒160/min) with minimal or absent variability without any decelerations
    • FHR < 100/min or > 160/min with minimal or moderate variability 
  • Interpretation: requires ongoing observation to confirm fetal well-being
  • Management:
    • Depends on clinical assessment (Are there known reasons to explain the category II tracing? For example, maternal fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever usually causes fetal tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children.)
    • Try “fetal resuscitation Resuscitation The restoration to life or consciousness of one apparently dead. . Neonatal Respiratory Distress Syndrome” techniques:
Category ii fetal heart rate tracing

Category II fetal heart rate Heart rate The number of times the heart ventricles contract per unit of time, usually per minute. Cardiac Physiology tracing, which is indeterminate:
The baseline is normal, but there is minimal variability. There are no decelerations or accelerations in this tracing.

Image by Lecturio.

Category III: abnormal

  • Patterns:
    • Variability is minimal or absent with late or variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables decelerations present
    • Terminal bradycardia Bradycardia Bradyarrhythmia is a rhythm in which the heart rate is less than 60/min. Bradyarrhythmia can be physiologic, without symptoms or hemodynamic change. Pathologic bradyarrhythmia results in reduced cardiac output and hemodynamic instability causing syncope, dizziness, or dyspnea. Bradyarrhythmias: FHR < 100/min for ≥ 10 minutes
    • Sinusoidal pattern (represents fetal anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types)
  • Interpretation: indicates that fetus is acidotic and in distress 
  • Management: usually requires immediate delivery (e.g., urgent cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery)
Fetal heart rate tracing demonstrating a prolonged late deceleration

Fetal heart rate Heart rate The number of times the heart ventricles contract per unit of time, usually per minute. Cardiac Physiology tracing demonstrating a prolonged late deceleration Deceleration A decrease in the rate of speed. Blunt Chest Trauma:
Variability appears moderate, however, and there is a spontaneous return to baseline. If this pattern continues, this is a worrisome tracing, demonstrating fetal distress.

Image by Lecturio.

Fetal non-stress test (NST)

An NST is cardiotocometry performed for 20 minutes (or longer if needed) to assess antepartum fetal well-being, usually after 28 weeks. Non-stress tests are classified as either reactive or nonreactive rather than by categories used to describe continuous fetal monitoring.

Reactive NST 

  • ≥ 2 FHR accelerations in 20 minutes
  • Moderate variability is almost always present with ≥ 2 accelerations, though not required to be considered reactive
  • Variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables decelerations may be present.
  • A reassuring pattern: predicts a low likelihood of fetal death due to hypoxic injury within the next few days
  • Management: observation

Nonreactive NST 

  • < 2 FHR accelerations in 20 minutes 
  • Variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables decelerations may be present
  • Nonreassuring patterns: unable to rule out fetal death due to hypoxic injury within the next few days 
  • Management: 
    • Indicates that further monitoring is required (e.g., prolonged/continuous fetal monitoring, BPP). Example: normal FHR, moderate variability, no decelerations, but no accelerations (nonreactive) → continue to monitor with cardiotocography (infant may be in a sleep Sleep A readily reversible suspension of sensorimotor interaction with the environment, usually associated with recumbency and immobility. Physiology of Sleep cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation and become reactive over the next hour or 2)
    • Depending on the gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care and severity of the nonreassuring NST, immediate delivery may be considered. Example: bradycardia Bradycardia Bradyarrhythmia is a rhythm in which the heart rate is less than 60/min. Bradyarrhythmia can be physiologic, without symptoms or hemodynamic change. Pathologic bradyarrhythmia results in reduced cardiac output and hemodynamic instability causing syncope, dizziness, or dyspnea. Bradyarrhythmias with absent variability in a full-term infant → urgent cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery

Contraction stress test (CST)

A CST is similar to an NST but is performed with induced (e.g., with pitocin) or spontaneous contractions, which allows providers to assess the impacts of the contractions on the FHR pattern. Interpretations include:

  • Negative: 
    • No significant decelerations
    • A reassuring result 
  • Positive: 
    • Presence of late decelerations > 50% of the time
    • A nonreassuring result → intervention is indicated
  • Equivocal: presence of late decelerations < 50% of the time or inadequate contractions to make an assessment

Ultrasound-Based Tests

Biophysical profile Biophysical Profile Obstetric Imaging (BPP)

  • A noninvasive assessment of fetal well-being
  • Performed after 28 weeks
  • Includes 2 parts: 
    • Ultrasound assessment, evaluating: 
      • Fetal movement
      • Fetal breathing
      • Fetal tone
      • Amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity volume
    • NST to assess the FHR reactivity.
  • Each component receives a score of either 0 (abnormal) or 2 (normal) points. 
    • No partial credit (cannot earn a score of 1)
    • E.g., to get credit for fetal movement, 3 distinct movements must be visualized; if only 2 movements are seen, the infant gets 0 points for movement.
  • The BPP is scored out of 10 points (or 8 when an NST is not performed).
  • Interpretation: 
    • Total score ≥ 8 points: no signs of fetal compromise
    • Total score 6 points: unclear risk of fetal compromise
    • Total score ≤ 4 points: potential fetal compromise, intervention indicated
Table: Biophysical profile Biophysical Profile Obstetric Imaging scoring criteria
Component Minimal normal criteria (observation for 30 minutes) Score
Non-stress test Reactive pattern (≥ 2 episodes of FHR accelerations of ≥ 15/min and ≥ 15 seconds within 20 minutes) 2
Fetal movement ≥ 3 discrete body or limb movements 2
Fetal breathing ≥ 1 rhythmic breathing episode(s) lasting ≥ 30 seconds 2
Fetal tone ≥ 1 episode(s) of a fetal extremity or fetal spine Spine The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy extension Extension Examination of the Upper Limbs with return to flexion Flexion Examination of the Upper Limbs 2
Amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity volume A single deepest vertical pocket ≥ 2 cm with a horizontal dimension ≥ 1 cm 2

Umbilical artery Umbilical artery Specialized arterial vessels in the umbilical cord. They carry waste and deoxygenated blood from the fetus to the mother via the placenta. In humans, there are usually two umbilical arteries but sometimes one. Prenatal and Postnatal Physiology of the Neonate Doppler Doppler Ultrasonography applying the doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. Ultrasound (Sonography)

Umbilical artery Umbilical artery Specialized arterial vessels in the umbilical cord. They carry waste and deoxygenated blood from the fetus to the mother via the placenta. In humans, there are usually two umbilical arteries but sometimes one. Prenatal and Postnatal Physiology of the Neonate (UA) Doppler Doppler Ultrasonography applying the doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. Ultrasound (Sonography) studies (done on ultrasound machines) are used to help assess fetal well-being in pregnancies affected by fetal growth restriction Fetal growth restriction Fetal growth restriction (FGR), also known as intrauterine fetal growth restriction (IUGR), is an estimated fetal weight (EFW) or abdominal circumference < 10th percentile for gestational age. The term small for gestational age (SGA) is sometimes erroneously used interchangeably with FGR. Fetal Growth Restriction ( FGR FGR Fetal growth restriction (FGR), also known as intrauterine fetal growth restriction (IUGR), is an estimated fetal weight (EFW) or abdominal circumference < 10th percentile for gestational age. The term small for gestational age (sga) is sometimes erroneously used interchangeably with FGR. Fetal Growth Restriction).

  • Measures the direction and velocity of blood flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure through the UA, which is directly related to blood flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure through the placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity 
  • UA Doppler Doppler Ultrasonography applying the doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. Ultrasound (Sonography) studies provide assessment of placental function:
    • Diseased vessels in the placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity cause an increase in resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing to fetal blood flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure (commonly due to maternal hypertensive and diabetic disorders)
    • Resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing in the placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity → slower fetal blood flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure through the placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity → less effective O2 and nutrient exchange → poor growth → FGR FGR Fetal growth restriction (FGR), also known as intrauterine fetal growth restriction (IUGR), is an estimated fetal weight (EFW) or abdominal circumference < 10th percentile for gestational age. The term small for gestational age (sga) is sometimes erroneously used interchangeably with FGR. Fetal Growth Restriction
  • The UA waveform usually has a sawtooth pattern:
    • Higher/faster forward flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure during fetal systole Systole Period of contraction of the heart, especially of the heart ventricles. Cardiac Cycle
    • Lower/slower forward flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure during fetal diastole Diastole Post-systolic relaxation of the heart, especially the heart ventricles. Cardiac Cycle
  • The systolic-to-diastolic (S:D) ratio is calculated.
  • As resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing in the placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity increases, forward flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure during fetal diastole Diastole Post-systolic relaxation of the heart, especially the heart ventricles. Cardiac Cycle decreases to a much greater extent than flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure during systole Systole Period of contraction of the heart, especially of the heart ventricles. Cardiac Cycle → S:D ratio increases
  • In severe cases, diastolic flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure may be completely absent or even reversed.
  • Results are used to help guide decisions surrounding when to deliver an infant with FGR FGR Fetal growth restriction (FGR), also known as intrauterine fetal growth restriction (IUGR), is an estimated fetal weight (EFW) or abdominal circumference < 10th percentile for gestational age. The term small for gestational age (sga) is sometimes erroneously used interchangeably with FGR. Fetal Growth Restriction.

References

  1. Manning, A. F. (2021). Biophysical profile test for antepartum fetal assessment. UpToDate. Retrieved December 28, 2021, from https://www.uptodate.com/contents/biophysical-profile-test-for-antepartum-fetal-assessment
  2. Palomaki, G. E., Messerlian, G. M., Halliday, J. V. (2021). Prenatal screening for common aneuploidies using cell-free DNA. UpToDate. Retrieved December 28, 2021, from https://www.uptodate.com/contents/prenatal-screening-for-common-aneuploidies-using-cell-free-dna
  3. Messerlian, G. M., Farina, A., Palomaki, G. E. (2020). First-trimester combined test and integrated tests for screening for Down syndrome and trisomy 18. Retrieved December 28, 2021, from https://www.uptodate.com/contents/first-trimester-combined-test-and-integrated-tests-for-screening-for-down-syndrome-and-trisomy-18
  4. Springer, S. C. (2020). Prenatal diagnosis and fetal therapy. MedScape. Retrieved December 28, 2021, from https://emedicine.medscape.com/article/936318-overview#a1
  5. Messerlian, G. M., Palomaki, G. E. (2021). Down syndrome: overview of prenatal screening. UpToDate. Retrieved December 28, 2021, from https://www.uptodate.com/contents/down-syndrome-overview-of-prenatal-screening
  6. Ghidini, A. (2021). Diagnostic amniocentesis. UpToDate. Retrieved December 28, 2021, from https://www.uptodate.com/contents/diagnostic-amniocentesis
  7. Ghidini, A. (2021). Chorionic villus sampling. UpToDate. Retrieved December 28, 2021, from https://www.uptodate.com/contents/chorionic-villus-sampling
  8. Ghidini, A. (2020). Fetal blood sampling. UpToDate. Retrieved December 28, 2021, from https://www.uptodate.com/contents/fetal-blood-sampling
  9. American College of Obstetricians and Gynecologists. (2020). Screening for fetal chromosomal abnormalities. ACOG Practice Bulletin Summary, no. 226. Obstetrics & Gynecology 136(4):859–867. https://doi.org/10.1097/aog.0000000000004107 

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