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PubMed This is a summary of 18 peer-reviewed journal articles Updated
Maternal-Fetal Medicine

The Biology of Gastroschisis: Diagnosis and Types

At a Glance

Gastroschisis is a congenital defect usually caused by a random vascular event early in pregnancy, causing a baby's intestines to develop outside the abdominal wall. It is diagnosed via ultrasound and classified as simple (healthy bowel) or complex (damaged bowel).

Understanding the biology of gastroschisis helps take the mystery out of the diagnosis. It is not caused by a genetic “blueprint” error, but rather by a physical event that occurs early in development. This page explains how that event happens and how doctors use technology to monitor your baby’s progress.

The Biological “Spark”: A Vascular Event

Most researchers believe gastroschisis is caused by a vascular disruption [1]. Around the 4th to 8th week of pregnancy, the baby’s abdominal wall is forming. During this time, the right umbilical vein—which is normally supposed to disappear as the baby grows—may involute (shrink) or experience a tiny clot (thrombosis) prematurely [2][1].

This creates a small, localized area of weakness in the abdominal wall, usually to the right of the umbilical cord [1][3]. Because the abdominal wall cannot fully close at this spot, the intestines begin to develop outside the body in the amniotic fluid. This is often described as a “random” event, which is why it is rarely associated with other birth defects or genetic syndromes [4][5].

How Doctors Diagnose Gastroschisis

The diagnosis typically happens in two stages:

  1. Serum Screening: During the second trimester, you may have a blood test called MSAFP (Maternal Serum Alpha-Fetoprotein) [6]. Because the baby’s intestines are exposed to the amniotic fluid, protein levels in your blood often rise significantly, signaling that further testing is needed [7][8].
  2. High-Resolution Ultrasound: This is the primary tool for diagnosis [7]. On an ultrasound, doctors look for “free-floating” loops of bowel in the amniotic fluid that are not contained within a sac [9].

Defining Simple vs. Complex Gastroschisis

Once diagnosed, doctors will monitor the baby to determine which “type” of gastroschisis they have. This distinction is the most important factor in predicting the baby’s needs after birth.

  • Simple (Classic) Gastroschisis: This accounts for the majority of cases. The bowel looks healthy on ultrasound, and there are no other complications like blockages or damage to the intestines [10].
  • Complex Gastroschisis: This occurs when the bowel is damaged. This can include atresia (a blockage or missing section of the bowel), necrosis (damaged tissue), or volvulus (the bowel twisting on itself) [10][11].

The Warning Sign: “Vanishing Gastroschisis”

Sometimes, the small hole in the abdominal wall begins to narrow or close while the baby is still in the womb. This is called vanishing (or closing) gastroschisis [12][13].

While it might sound like the condition is “fixing itself,” it is actually a situation that requires very close monitoring. If the hole becomes too small (often measured as less than 8–12 mm), it can pinch the intestines that are outside the body, cutting off their blood supply [14][15].

Ultrasound markers for closing gastroschisis include:

  • Intra-abdominal bowel dilation (IABD): The part of the bowel inside the baby begins to widen (often >10–18 mm) because it is becoming blocked at the exit point [14][15][16].
  • Disappearing bowel loops: The intestines that were visible outside the baby seem to “disappear” or shrink significantly because they are being damaged or pulled back in [13][17].
  • Reduced fetal growth: The baby may stop gaining weight at the expected rate [17].

If doctors see these signs, they may adjust the timing of delivery to ensure the baby is born before the bowel sustains significant damage [15][18].

Common questions in this guide

How do doctors diagnose gastroschisis during pregnancy?
Doctors usually diagnose gastroschisis using a high-resolution ultrasound to look for the baby's intestines floating outside the belly without a sac. They may also see high protein levels on a maternal blood test called MSAFP, which alerts them to look closer.
What is the difference between simple and complex gastroschisis?
Simple gastroschisis means the exposed bowel looks healthy and has no other complications. Complex gastroschisis means the bowel has sustained damage, such as a blockage, twisted tissue, or dead areas, which requires more specialized care after birth.
What causes gastroschisis to happen?
Most researchers believe gastroschisis is caused by a random vascular event early in pregnancy. A tiny blood clot or early shrinking of an umbilical vein creates a weak spot in the baby's developing abdominal wall, allowing the intestines to slip out into the amniotic fluid.
What is vanishing gastroschisis and why is it dangerous?
Vanishing or closing gastroschisis occurs when the hole in the baby's abdominal wall begins to shrink or close while they are still in the womb. This can pinch the exposed intestines and cut off their blood supply, causing severe damage if the baby is not monitored closely.
What are the ultrasound signs that gastroschisis might be closing?
On an ultrasound, doctors look for warning signs like the bowel widening inside the baby's belly, the exposed loops outside the body seeming to shrink or disappear, and the baby's overall growth slowing down. These signs may prompt the medical team to adjust the delivery date.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What specific ultrasound signs are you seeing that indicate this is 'simple' versus 'complex' gastroschisis?
  2. 2.How often are you measuring the size of the abdominal opening, and is it showing any signs of narrowing or 'closing'?
  3. 3.What is the current measurement of the intra-abdominal bowel (the part inside the baby), and does it suggest a higher risk for complications?
  4. 4.In the case of 'vanishing gastroschisis,' how does your surgical team's approach change at birth?
  5. 5.If the bowel loops disappear on a future ultrasound, does that mean the condition has resolved, or does it require immediate intervention?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (18)
  1. 1

    Examining the Relationship Between Gastroschisis and Placental Fetal Vascular Malperfusion.

    Ruschkowski B, Nasr A, Oltean I, et al.

    Pediatric and developmental pathology : the official journal of the Society for Pediatric Pathology and the Paediatric Pathology Society 2021; (24(6)):531-541 doi:10.1177/10935266211029629.

    PMID: 34284667
  2. 2

    Genetic variants conferring susceptibility to gastroschisis: a phenomenon restricted to the interaction with the environment?

    Salinas-Torres VM, Salinas-Torres RA, Cerda-Flores RM, Martínez-de-Villarreal LE

    Pediatric surgery international 2018; (34(5)):505-514 doi:10.1007/s00383-018-4247-z.

    PMID: 29550988
  3. 3

    Extremely Rare Co-occurrence of Left Gastroschisis-Like Abdominal Wall Defect and an Omphalocele in a Very Low Birth Weight Infant: A Case Report.

    Mori T, Tomita H, Tsukizaki A, et al.

    Surgical case reports 2025; (11(1)) doi:10.70352/scrj.cr.25-0453.

    PMID: 41194792
  4. 4

    Insights into the etiology and embryology of gastroschisis.

    Beaudoin S

    Seminars in pediatric surgery 2018; (27(5)):283-288 doi:10.1053/j.sempedsurg.2018.08.005.

    PMID: 30413258
  5. 5

    The complex search for the cause of gastroschisis.

    de Freitas AB, Francisco RPV, Hoshida MS, et al.

    Birth defects research 2022; (114(19)):1291-1297 doi:10.1002/bdr2.2047.

    PMID: 35574732
  6. 6

    [Maternal serum alpha fetoprotein and free β-hCG of second trimester for screening of fetal gastroschisis and omphalocele].

    Chen Y, Zhang W, Lu S, et al.

    Zhejiang da xue xue bao. Yi xue ban = Journal of Zhejiang University. Medical sciences 2017; (46(3)):268-273 doi:10.3785/j.issn.1008-9292.2017.06.07.

    PMID: 29039168
  7. 7

    Pregnancy outcomes regarding maternal serum AFP value in second trimester screening.

    Bartkute K, Balsyte D, Wisser J, Kurmanavicius J

    Journal of perinatal medicine 2017; (45(7)):817-820.

    PMID: 27771626
  8. 8

    Is unexplained elevated maternal serum alpha-fetoprotein still important predictor for adverse pregnancy outcome?

    Başbuğ D, Başbuğ A, Gülerman C

    Ginekologia polska 2017; (88(6)):325-330 doi:10.5603/GP.a2017.0061.

    PMID: 28727133
  9. 9

    Prenatal diagnosis and management of omphalocele.

    Verla MA, Style CC, Olutoye OO

    Seminars in pediatric surgery 2019; (28(2)):84-88 doi:10.1053/j.sempedsurg.2019.04.007.

    PMID: 31072463
  10. 10

    Using three-dimensional ultrasound in predicting complex gastroschisis: A longitudinal, prospective, multicenter cohort study.

    Hijkoop A, Lap CCMM, Aliasi M, et al.

    Prenatal diagnosis 2019; (39(13)):1204-1212 doi:10.1002/pd.5568.

    PMID: 31600419
  11. 11

    Gastroschisis Complicated by Colonic Atresia.

    Everett HM, Bhattacharya SD

    The American surgeon 2023; (89(6)):2762-2763 doi:10.1177/00031348211048848.

    PMID: 34730464
  12. 12

    Closing gastroschisis: The good, the bad, and the not-so ugly.

    Perrone EE, Olson J, Golden JM, et al.

    Journal of pediatric surgery 2019; (54(1)):60-64 doi:10.1016/j.jpedsurg.2018.10.033.

    PMID: 30482541
  13. 13

    A case of vanishing gastroschisis with short bowel syndrome treated by total parenteral nutrition and intestinal lengthening procedures.

    Guanà R, Marocco L, Garofalo S, et al.

    SAGE open medical case reports 2023; (11()):2050313X231157490 doi:10.1177/2050313X231157490.

    PMID: 36896328
  14. 14

    What prenatal ultrasound features are predictable of complex or vanishing gastroschisis? A retrospective study.

    Geslin D, Clermidi P, Gatibelza ME, et al.

    Prenatal diagnosis 2017; (37(2)):168-175 doi:10.1002/pd.4984.

    PMID: 27981591
  15. 15

    Regional cluster of vanishing gastroschisis: A comparative study of antenatal and post-natal outcomes.

    Granger J, Do-Wyeld M, Cundy TP, et al.

    Journal of paediatrics and child health 2020; (56(3)):420-425 doi:10.1111/jpc.14644.

    PMID: 31614068
  16. 16

    Prenatal Risk Factors and Outcomes in Gastroschisis: A Meta-Analysis.

    D'Antonio F, Virgone C, Rizzo G, et al.

    Pediatrics 2015; (136(1)):e159-69 doi:10.1542/peds.2015-0017.

    PMID: 26122809
  17. 17

    Closing/Closed Gastroschisis (CGS): Antenatal Predictors and Surgical Strategies in Cases of Unique Anatomy from a Case Series.

    Morozov D, Vanyan L, Morozova M, et al.

    Children (Basel, Switzerland) 2026; (13(3)) doi:10.3390/children13030408.

    PMID: 41897120
  18. 18

    Vanishing Gastroschisis: The Importance of Prenatal Diagnosis in a Seemingly Normal Abdomen.

    Massaguer C, De Haro Jorge I, Saura García L, et al.

    European journal of pediatric surgery reports 2025; (13(1)):e151-e154 doi:10.1055/a-2692-6661.

    PMID: 40951522

This page explains the biology and diagnostic ultrasound findings of gastroschisis for educational purposes only. Always consult your maternal-fetal medicine specialist or pediatric surgeon to interpret your specific ultrasound results and pregnancy care plan.

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