Gastroschisis

Gastroschisis is a congenital abdominal wall defect characterized by the complete lack of closure of the abdominal musculature. A portion of intestine does not return to the abdominal cavity, thereby remaining in its early embryonic herniated state but with no coverings. Diagnosis is made by prenatal ultrasonography. Findings include a paraumbilical wall defect with uncovered herniated intestines. Fetal surveillance and bowel monitoring are done to measure fetal growth and amniotic fluid volume, as well as observe any bowel changes. The mode and timing of delivery depend on these factors. Neonatal care includes protection of the exposed bowel, fluid resuscitation, and airway maintenance. Primary closure can be performed within hours of birth. The presence of a large gastroschisis or thickened and dilated bowel warrants delayed closure, with the use a bowel covering or “silo,” and serial bowel reduction.

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

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Overview

Definition

Gastroschisis is a full-thickness defect of the anterior abdominal wall Anterior abdominal wall The anterior abdominal wall is anatomically delineated as a hexagonal area defined superiorly by the xiphoid process, laterally by the midaxillary lines, and inferiorly by the pubic symphysis. Anterior Abdominal Wall through which the intestine and/or other abdominal viscera freely protrude.

  • No membrane or sac covers the bowel/intestine.
  • The defect is often to the right of the umbilical insertion site.

Embryology

  • Gastrointestinal (GI) system development from 3 germinal layers:
    • Mesoderm: connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue (wall of gut tube, blood vessels and smooth muscle)
    • Endoderm: epithelial lining
    • Ectoderm: epidermis and neural crest (neurons of the GI tract)
  • GI tract divisions:
    • Foregut: oral cavity to the 1st part of the duodenum
    • Midgut: mid-duodenum to the 1st ⅔ of transverse colon Colon The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal. Colon, Cecum, and Appendix
    • Hindgut: last ⅓ of the transverse colon Colon The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal. Colon, Cecum, and Appendix to the upper anus
  • 6th week of gestation:
    • Rapid growth of the GI tract
    • Midgut herniates through the umbilical ring, developing entirely outside the peritoneal cavity.
  • 10th week of gestation:
    • Abdominal cavity is large enough for the developing midgut.
    • Midgut completes rotation and returns to the abdominal cavity.
Normal process of herniation during embryologic development

Diagram showing the normal process of intestinal rotation and herniation during embryologic development

A: the midgut (multi-colored loop) before herniation.
B1-B3: as it grows rapidly, the midgut herniates through the umbilical ring, and starts rotation.
C: The midgut returns to the abdominal cavity.

Image by Lecturio.

Epidemiology

  • Prevalence: 3–4 per 10,000 births
  • Similar incidence in male and female newborns
  • In 10% of cases, gastroschisis is associated with anomalies outside the GI tract. 
  • Higher risk of preterm delivery in pregnancies with gastroschisis (28%) compared with those without gastroschisis (6%)
  • Maternal risk factors:
    • Young age (< 20 years)
    • Low body mass index (BMI)
    • Exposure to cigarette smoke
    • Intake of aspirin and ibuprofen
    • Intake of decongestants (pseudoephedrine, phenylpropanolamine)

Pathophysiology

Embryologic hypotheses leading to herniation of the bowel: 

  • Defective formation
    • Failure of mesoderm to form in the body wall
    • Abnormal folding of body wall resulting in a ventral body wall defect
  • Disruption of the abdominal wall
    • Rupture of the amnion (sac protecting the embryo) around the umbilical ring 
    • Abnormal involution of the right umbilical vein leading to weakening of the body wall
    • Disruption of the right vitelline (yolk sac) artery leading to infarction at the base of the cord and subsequent body wall damage

Diagnosis and Monitoring

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

  • Ultrasonography
    • Prenatal diagnosis made as early as 14 weeks, but usually around 20 weeks’ gestation
    • Finding(s): 
      • Paraumbilical abdominal wall defect (on the right, never through the umbilicus)
      • Herniated intestines without a covering sac
      • Intestines freely floating in amniotic fluid
      • 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 (most common amniotic fluid finding)
      • Occasionally other visceral organs also herniated (e.g., liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver)
  • Laboratory test: elevated maternal serum ɑ-fetoprotein (AFP)
    • Elevated AFP is suggestive of but non-specific for gastroschisis (seen also in spina bifida and anencephaly).
    • Lab testing alone is insufficient for a diagnosis of gastroschisis.

Monitoring

  • Fetal monitoring
    • Assess fetal growth including amniotic fluid volume
    • Typically started at 24 weeks
    • Look for intrauterine growth restriction (IUGR): associated with increased risk of fetal demise
  • Fetal bowel
    • Serial sonographic evaluation of the stomach Stomach The stomach is a muscular sac in the upper left portion of the abdomen that plays a critical role in digestion. The stomach develops from the foregut and connects the esophagus with the duodenum. Structurally, the stomach is C-shaped and forms a greater and lesser curvature and is divided grossly into regions: the cardia, fundus, body, and pylorus. Stomach and bowel
    • Check for substantial dilation (> 25 mm) or acute thickening and edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema
    • Prenatal complications associated with bowel dilation:
      • Umbilical cord compression
      • Bowel obstruction
  • Antepartum fetal surveillance
    • Biophysical profile with nonstress test and amniotic fluid index
    • Usually started around 32 weeks
  • Fetal genetic studies
    • Considered in cases with extraintestinal structural anomalies (to determine associated chromosomal abnormalities)
    • Information regarding prognosis, delivery management, and neonatal care needed

Clinical Presentation

Newborn Newborn A neonate, or newborn, is defined as a child less than 28 days old. A thorough physical examination should be performed within the first 24 hours of life to identify abnormalities and improve outcomes by offering timely treatment. Physical Examination of the Newborn findings

  • Full-thickness paraumbilical abdominal wall defect, usually to the right of the umbilical cord insertion site
  • Eviscerated bowel not covered by a sac 
  • Bowel appearance affected by:
    • Exposure to amniotic fluid
    • Amount of time of bowel is exposed 
    • Longer exposure to amniotic fluid → bowel is matted, thick, and covered with inflammatory rind
  • Abdominal defect is usually < 4 cm.

Categories

  • Simple gastroschisis: 
    • 75% of cases
    • Intact, uncompromised, continuous bowel
  • Complex gastroschisis: 
    • Associated with intestinal stenosis, atresia, perforation, necrosis or volvulus Volvulus A volvulus is the twisting or axial rotation of a portion of the bowel around its mesentery. The most common site of volvulus in adults is the colon; most frequently the sigmoid volvulus. Patients typically present with symptoms of bowel obstruction such as abdominal pain, distension, vomiting, and constipation/obstipation. Volvulus
    • Related to vascular compromise caused by the herniated bowel
    • More GI, infectious, and respiratory diseases
    • Higher risk for in-hospital mortality and complications (bowel obstruction, short bowel syndrome Short bowel syndrome Short bowel syndrome is a malabsorptive condition most commonly associated with extensive intestinal resection for etiologies such as Crohn's disease, bowel obstruction, trauma, radiation therapy, and vascular insufficiency. The short length of bowel results in insufficient surface area for fluid and electrolyte absorption. Short Bowel Syndrome, and need for tube feedings on discharge)

Management and Prognosis

Delivery

  • Requires coordination of care among maternal-fetal medicine specialist, neonatologist, and pediatric surgeon
  • Delivery is recommended in a center with optimal neonatal care resources. 
  • Timing:
    • Affected by multiple factors, including:
      • Gestational age (lung maturity)
      • Ultrasound findings (fetal growth and bowel status)
      • Fetal testing results
    • Spontaneous 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 (for pregnancies with gastroschisis) occurs at a mean gestational age of 36 weeks.
  • Mode of delivery:
    • Uncomplicated gastroschisis: not a contraindication to vaginal delivery
    • Marked liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver herniation: Cesarean section should be considered.

Neonatal care

  • Reduce intestinal injury and reduce fluid loss:
    • Protect exposed bowel by wrapping bowel with sterile saline dressings covered with plastic wrap.
    • In some centers, lower half of the neonate is placed into a plastic bag (allows protection and visualization of bowel perfusion).
  • Fluid and electrolyte resuscitation (expected fluid losses are 23 times that of a healthy neonate)
  • Prophylactic broad-spectrum antibiotics (cover for maternal vaginal flora)
  • Orogastric tube insertion to decompress the stomach Stomach The stomach is a muscular sac in the upper left portion of the abdomen that plays a critical role in digestion. The stomach develops from the foregut and connects the esophagus with the duodenum. Structurally, the stomach is C-shaped and forms a greater and lesser curvature and is divided grossly into regions: the cardia, fundus, body, and pylorus. Stomach
  • Airway maintenance and respiratory support as needed

Surgery

  • Primary closure
    • Surgery performed within hours of birth
    • To minimize intestinal injury during reduction, abdominal defect is increased by 1–2 cm. 
    • Successful in 70% of cases
  • Delayed closure
    • In cases of thickened and distended bowel loops
    • Eviscerated bowel is contained within a sterile covering (silastic silo).
    • The bag and bowel are suspended over the infant, allowing decompression of bowel loops by gravity.
    • Serial reduction of bowel contents performed
Gastroschisis silo illustration

Gastroschisis silo

Image by Lecturio.

Prognosis

  • Gastroschisis: most favorable outcome compared with other abdominal wall defects
  • Survival rate of neonates born in North America: 98%
  • Sepsis Sepsis Organ dysfunction resulting from a dysregulated systemic host response to infection separates sepsis from uncomplicated infection. The etiology is mainly bacterial and pneumonia is the most common known source. Patients commonly present with fever, tachycardia, tachypnea, hypotension, and/or altered mentation. Sepsis and Septic Shock: only significant predictor of mortality

Differential Diagnosis

  • Omphalocele Omphalocele Omphalocele is a congenital anterior abdominal wall defect in which the intestines are covered by peritoneum and amniotic membranes. The condition results from the failure of the midgut to return to the abdominal cavity by 10 weeks' gestation. Omphalocele: similar to gastroschisis, but due to a failure of the bowel to return to the ventral cavity after normal herniation. The abdominal viscera (including the liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver) remain herniated through the umbilicus, covered by amnion and peritoneum Peritoneum The peritoneum is a serous membrane lining the abdominopelvic cavity. This lining is formed by connective tissue and originates from the mesoderm. The membrane lines both the abdominal walls (as parietal peritoneum) and all of the visceral organs (as visceral peritoneum). Peritoneum and Retroperitoneum. Unlike gastroschisis, approximately half of cases of omphalocele are associated with other birth defects and chromosomal abnormalities.
  • Pentalogy of Cantrell: a rare syndrome consisting of multiple congenital abnormalities, including a lower sternal defect, anterior diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm defect, pericardial defect, abdominal wall defect, and congenital heart anomalies. Diagnosis is made prenatally by ultrasonography. Treatment requires complex medical and surgical care.
  • Bladder exstrophy-epispadias complex: a spectrum of congenital defects: epispadias (failed closure of urethra), bladder exstrophy, and cloacal exstrophy (most severe defect, which includes anal atresia and an omphalocele). Treatment is surgical, with goals to close abdominal wall defect, achieve urinary continence, and reconstruct the genito-urinary area.
  • Umbilical hernia: presents as a protrusion in the neonate’s umbilical area. There is incomplete closure of the fascia of the umbilical ring but with intact skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin covering the ring. It is important to determine the reducibility, as incarcerated hernia is a complication. Surgery is indicated for defects > 1.5 cm in those > 2 years of age and for complications, including strangulation, incarceration, or rupture.

References

  1. Bhatia, A., Shatanof, R., Bordoni, B. (2020) Embryology, Gastrointestinal. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK537172/ 
  2. Bradnock, T. et al. (2011). Gastroschisis: one year outcomes from national cohort study. British Medical Journal. doi: 10.1136/bmj.d6749
  3. Feldkamp, M., Carey, J., Sadler, T. (2007). Development of Gastroschisis: Review of hypothesis, and implications for research. American Journal of Medical Genetics. https://doi.org/10.1002/ajmg.a.31578
  4. Ebert, A. et al. (2009). The Exstrophy-epispadias complex. Orphanet Journal of rare diseases. 4:23. doi: 10.1186/1750-1172-4-23
  5. Glasser, J., Windle, M., Carter, B. (2019). Pediatric Omphalocele and Gastroschisis (Abdominal wall defects). Medscape. Retrieved 4 Oct 2020, from https://emedicine.medscape.com/article/975583-overview#a5
  6. Rentea, R., Gupta, V. (2020). Gastroschisis. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK557894/
  7. Stephenson, C. et al. (2020). Gastroschisis. UpToDate. Retrieved 4 Oct 2020, from https://www.uptodate.com/contents/gastroschisis?search=gastroschisis
  8. Troullioud Lucas, A., Jaafar, S., Mendez, M. (2020). Pediatric Umbilical Hernia. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK459294/-

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