Spontaneous Abortion

Spontaneous abortion, also known as miscarriage, is the loss of a pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care before 20 weeks’ gestation. However, the layperson use of the term “abortion” is often intended to refer to induced termination of a pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care, whereas “miscarriage” is preferred for spontaneous loss. Most spontaneous abortions occur within the 1st 12 weeks of gestation and can be caused by several factors such as infection, trauma, and genetic and autoimmune causes. There are different types of spontaneous abortions, including threatened, inevitable, incomplete, complete, and missed abortions. Spontaneous abortions are diagnosed based on history, physical examination, and ultrasound findings. Management options include expectant, medical, or surgical therapy.

Last update:

Table of Contents

Share this concept:

Share on facebook
Share on twitter
Share on linkedin
Share on reddit
Share on email
Share on whatsapp

Overview

Definition

Spontaneous abortion is the noninduced loss of pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care before 20 weeks’ gestation.

Epidemiology

  • Common complication of early pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care
  • Accounts for pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care loss in 10%–20% of clinically recognized pregnancies
  • Occurs in all age groups, but the incidence is higher in women > 35 years of age
  • There is conflicting data on racial predilection.

Classification

Spontaneous abortion can be classified into the following types (see “Clinical Presentation and Diagnosis” for details):

  • Threatened abortion
  • Inevitable abortion
  • Incomplete abortion
  • Complete abortion
  • Missed abortion

Etiology

There are many potential causes for spontaneous abortion.

Maternal factors

  • Advanced maternal age (> 35 years)
  • Medical conditions:
    • 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
    • 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
    • Diabetes
    • Obesity Obesity Obesity is a condition associated with excess body weight, specifically with the deposition of excessive adipose tissue. Obesity is considered a global epidemic. Major influences come from the western diet and sedentary lifestyles, but the exact mechanisms likely include a mixture of genetic and environmental factors. Obesity
    • Hyperthyroidism Hyperthyroidism Thyrotoxicosis refers to the classic physiologic manifestations of excess thyroid hormones and is not synonymous with hyperthyroidism, which is caused by sustained overproduction and release of T3 and/or T4. Graves' disease is the most common cause of primary hyperthyroidism, followed by toxic multinodular goiter and toxic adenoma. Thyrotoxicosis and Hyperthyroidism
    • Coagulopathies
    • Autoimmune conditions
  • Infections:
    • Cytomegalovirus Cytomegalovirus CMV is a ubiquitous double-stranded DNA virus belonging to the Herpesviridae family. CMV infections can be transmitted in bodily fluids, such as blood, saliva, urine, semen, and breast milk. The initial infection is usually asymptomatic in the immunocompetent host, or it can present with symptoms of mononucleosis. Cytomegalovirus
    • Parvovirus B19 Parvovirus B19 Primate erythroparvovirus 1 (generally referred to as parvovirus B19, B19 virus, or sometimes erythrovirus B19) ranks among the smallest DNA viruses. Parvovirus B19 is of the family Parvoviridae and genus Erythrovirus. In immunocompetent humans, parvovirus B19 classically results in erythema infectiosum (5th disease) or "slapped cheek syndrome." Parvovirus B19
    • Toxoplasmosis Toxoplasmosis Toxoplasmosis is an infectious disease caused by Toxoplasma gondii, an obligate intracellular protozoan parasite. Felines are the definitive host, but transmission to humans can occur through contact with cat feces or the consumption of contaminated foods. The clinical presentation and complications depend on the host's immune status. Toxoplasma/Toxoplasmosis
    • Malaria Malaria Malaria is an infectious parasitic disease affecting humans and other animals. Most commonly transmitted via the bite of a female Anopheles mosquito infected with microorganisms of the Plasmodium genus. Patients present with fever, chills, myalgia, headache, and diaphoresis. Malaria
    • 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 trachomatis
  • Anatomic abnormalities:
    • Cervical insufficiency
    • Submucosal leiomyomas
    • Congenital uterine anomalies, e.g., septate uterus
    • Intrauterine adhesions
  • Maternal chromosomal abnormalities
  • Recreational drug use

Fetal factors

  • Chromosomal abnormalities (account for 50% of all spontaneous abortions)
    • Autosomal trisomies
    • Turner syndrome Turner syndrome Turner syndrome is a genetic condition affecting women, in which 1 X chromosome is partly or completely missing. The classic result is the karyotype 45,XO with a female phenotype. Turner syndrome is associated with decreased sex hormone levels and is the most common cause of primary amenorrhea. Turner Syndrome (monosomy X)
  • Congenital anomalies

Paternal factors

  • Increasing paternal age
  • Paternal chromosomal abnormalities

Miscellaneous

  • Trauma
  • Environmental exposure to toxins:
    • Tobacco
    • Chemotherapeutic agents
    • Certain industrial chemicals:
      • Toluene
      • Formaldehyde

Clinical Presentation and Diagnosis

Clinical presentation

  • Individuals may be asymptomatic.
  • The most common symptom, if present, is vaginal bleeding.
  • Other symptoms may include:
    • Abnormal vaginal discharge
    • Abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain
    • Menstrual-like cramping

Diagnostic evaluation

The diagnosis is made by a combination of history, physical examination, and ultrasound findings.

  • Key features to evaluate on clinical examination:
    • Presence or absence of vaginal bleeding
    • Dilation of the cervical os
    • Hemodynamic stability
  • Key features to evaluate on ultrasound:
    • Presence of products of conception in the uterus
    • Presence or absence of fetal cardiac activity
    • Size of the gestational sac or fetus
  • Additional studies:
    • Check maternal blood type and Rh factor
    • CBC to evaluate for acute blood loss 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
    • Beta-hCG levels

Clinical and ultrasound findings by type

The types of spontaneous abortions differ based on clinical examination and ultrasound findings.

Threatened abortion:

  • Vaginal bleeding is present.
  • Abdominal cramps or pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain may be present.
  • Fetal cardiac activity is present.
  • Cervical os is closed.
  • Products of conception are not expelled.
  • Generally self-limiting; prognosis is worse with heavier bleeding.

Inevitable abortion:

  • Vaginal bleeding is present.
  • Abdominal cramps and pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain may be present.
  • Fetal cardiac activity may be present.
  • Cervical os is dilated.
  • Products of conception are not expelled.

Incomplete abortion:

  • Vaginal bleeding is present.
  • Abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain is present.
  • Fetal cardiac activity may be present.
  • Cervical os is dilated.
  • POC is partially expelled.

Complete abortion:

  • Vaginal bleeding is often present.
  • Abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain may be present.
  • Cervical os is closed.
  • Products of conception are completely expelled.

Missed abortion:

  • Vaginal bleeding is often absent but may be present.
  • Abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain is often absent.
  • Fetal cardiac activity is absent.
  • Cervical os is closed.
  • Products of conception are not expelled.
Differences between types of spontaneous abortion

Differences between the types of spontaneous abortion:
Important differentiating factors include the presence or absence of vaginal bleeding, whether the cervical os is dilated or closed, the presence or absence of the products of conception, and fetal cardiac activity.

Image by Lecturio.

Management

General approach

  • The appropriate therapy for spontaneous abortions depends on the type of abortion and hemodynamic stability of the individual.
  • Rh(D)-negative women should receive Rh(D) immunoglobulin if vaginal bleeding is present.
  • The 3 main options for therapy are expectant, medical, or surgical management.

Expectant management

  • Appropriate for hemodynamically stable individuals
  • Treatment of choice for threatened abortions
  • May involve avoiding intercourse and decreasing strenuous physical activities
  • Close follow-up with clinic visits and ultrasound is crucial.
  • May take weeks to resolve
  • In certain situations, surgical intervention may become necessary if expectant management fails.

Medical management

  • Appropriate for:
    • Hemodynamically stable individuals
    • Poor surgical candidates
  • May be used for inevitable, incomplete, or missed abortions
  • Involves pharmacological agents to aid in cervical dilation and expulsion of the products of conception
    • Misoprostol:
      • Given orally or vaginally
      • Prostaglandin E1 analog → uterotonic
    • Premedication may be given with mifepristone:
      • Can increase efficacy
      • Competitively binds to progestin receptor → primes the cervix and uterus for the effects of misoprostol
  • Pain control with NSAIDs
  • Close follow-up is crucial to ensure the success of therapy.
  • May take days to weeks to resolve
  • Surgical management might be necessary if medical treatment fails.

Surgical management

  • Appropriate for:
    • Hemodynamically unstable individuals
    • Individuals who decline other management options
    • Individuals unable to adhere to a follow-up plan
    • Individuals who have not fully expelled the products of conception with expectant or medical management
  • Dilation and curettage is the preferred surgical intervention for abortions.
  • Resolves immediately after surgery.
  • Risks include:
    • Uterine perforation
    • Infection
    • Hemorrhage
    • Subsequent formation of uterine adhesions (also known as synechiae)

Differential Diagnosis

  • Septic abortion: a condition that may occur as a result of an infection in the setting of a missed, inevitable, or incomplete abortion. The infection typically starts as a localized infection of the uterus and then spreads systemically. The diagnosis is clinical and should be suspected in women with 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, uterine pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, tenderness, and vaginal bleeding before or after pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care loss. The definitive treatment, in addition to broad-spectrum antibiotics, is the prompt evacuation of the uterus using dilation and curettage.
  • Ectopic pregnancy Ectopic pregnancy Ectopic pregnancy refers to the implantation of a fertilized egg (embryo) outside the uterine cavity. The main cause is disruption of the normal anatomy of the fallopian tube. Ectopic Pregnancy: implantation of a fertilized egg (embryo) outside the uterine cavity. The main cause of ectopic pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care is disruption of the normal anatomy of the fallopian tubes. Consequently, affected individuals may suffer from acute abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain and vaginal bleeding as the developing embryo increases in size. Ultrasound and determination of beta-hCG levels are used in the diagnosis. Management depends on the condition of the individual and is usually medical or surgical. Severe cases involving rupture of the fallopian tube and hemorrhage are considered surgical emergencies.
  • Hydatidiform mole (molar pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care): a gestational trophoblastic disease Gestational trophoblastic disease Gestational trophoblastic diseases are a spectrum of placental disorders resulting from abnormal placental trophoblastic growth. These disorders range from benign molar pregnancies (complete and partial moles) to neoplastic conditions such as invasive moles and choriocarcinoma. Gestational Trophoblastic Disease arising from the placenta Placenta The placenta consists of a fetal side and a maternal side, and it provides a vascular communication between the mother and the fetus. This communication allows the mother to provide nutrients to the fetus and allows for removal of waste products from fetal blood. Placenta, Umbilical Cord, and Amniotic Cavity. These premalignant tumors are classified as complete (no fetal tissue, diploid) or partial (some fetal tissue, triploid). The presentation is more severe with a complete mole, and women may present with 1st-trimester vaginal bleeding, nausea, and preeclampsia. Diagnosis is based on high beta-hCG levels and by using ultrasound, which may show the characteristic “snowstorm” appearance with a complete mole. Surgical removal of the molar pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care is needed.

References

  1. Cunningham, F.G. (2018). Abortion. In Spong, C.Y: (Ed.), Williams Obstetrics. (25th ed., pp. 344–348). New York: Mcgraw Hill Medical.
  2. Gabbe, S.G. (2017). Pregnancy Loss. In Gabbe, S. (Ed.), Obstetrics Normal and Problem Pregnancies. (6th ed., pp. 592–608). Elsevier. 
  3. Prager, S., Micks, E., Dalton, V.K. (2021). Pregnancy loss (miscarriage): Terminology, risk factors, and etiology. UpToDate. Retrieved September 2, 2021, from https://www.uptodate.com/contents/pregnancy-loss-miscarriage-terminology-risk-factors-and-etiology
  4. Prager, S., Micks, E., Dalton, V.K. (2021). Pregnancy loss (miscarriage): Clinical presentations, diagnosis, and initial evaluation. UpToDate. Retrieved September 2, 2021, from https://www.uptodate.com/contents/pregnancy-loss-miscarriage-clinical-presentations-diagnosis-and-initial-evaluation
  5. Dulay, A.T. (2020). Spontaneous abortion. [online] MSD Manual Professional Version. Retrieved September 2, 2021, from https://www.msdmanuals.com/professional/gynecology-and-obstetrics/abnormalities-of-pregnancy/spontaneous-abortion

Learn even more with Lecturio:

Complement your med school studies with Lecturio’s all-in-one study companion, delivered with evidence-based learning strategies.

Study on the Go

Lecturio Medical complements your studies with evidence-based learning strategies, video lectures, quiz questions, and more – all combined in one easy-to-use resource.

¡Hola!

Esta página está disponible en Español.

🍪 Lecturio is using cookies to improve your user experience. By continuing use of our service you agree upon our Data Privacy Statement.

Details