Mastering Medical
USMLE Step 1 · Embryology & Anatomy

Gastroschisis vs Omphalocele

How to tell Gastroschisis and Omphalocele apart when a board question makes them look alike.

Fastest separator

Gastroschisis is isolated, right-sided, and uncovered; omphalocele is midline, membrane-covered, and syndromic.

Side by side

GastroschisisOmphalocele
Key clue

Gastroschisis is an isolated full-thickness abdominal wall defect, usually right of the umbilicus, with free-floating bowel and elevated maternal AFP.

Omphalocele is midline herniation into a membrane-covered sac at the umbilical ring, raises maternal AFP, and is associated with Beckwith-Wiedemann plus trisomy 13 or 18.

Mechanism

Gastroschisis is a paraumbilical abdominal wall defect with bowel exposed directly to amniotic fluid and not covered by peritoneum.

Omphalocele is herniation through umbilical ring covered by peritoneum/amniotic membrane and associated with other anomalies or aneuploidy.

Labs and tests

Elevated maternal AFP with uncovered bowel loops right of the umbilicus supports gastroschisis.

Elevated maternal AFP plus membrane-covered midline sac and syndromic aneuploidy associations support omphalocele.

The trap

Gastroschisis is uncovered bowel next to umbilicus; omphalocele is covered midline herniation through umbilical ring with anomaly risk.

The repair move

Before naming the answer, force the stem through the separator: Gastroschisis is uncovered bowel next to umbilicus; omphalocele is covered midline herniation through umbilical ring with anomaly risk.

Try a free question

Core

A newborn delivered by C-section is found to have a 5-cm full-thickness abdominal wall defect to the right of an intact umbilical cord, with bowel loops floating freely without a covering membrane. Maternal AFP was elevated during pregnancy. The infant has no other anomalies and a normal karyotype. Which condition is this?

Show answer and explanation

Answer: A. Gastroschisis. Gastroschisis is an isolated full-thickness abdominal wall defect, typically to the RIGHT of the umbilicus, with bowel exposed directly to amniotic fluid (NO covering membrane). Maternal AFP is elevated. NOT typically associated with other congenital anomalies or aneuploidy. Bowel can be edematous and inflamed from amniotic fluid exposure.

Why the other choices are tempting

  • B. Omphalocele is MIDLINE, has a covering membrane (peritoneum/amnion), and is associated with other anomalies and aneuploidy (trisomy 13, 18, Beckwith-Wiedemann).
  • C. Umbilical hernia is a covered defect at the umbilicus with intact skin, typically small and presenting after birth.
  • D. Body stalk anomaly is a rare severe defect with absent umbilical cord and major thoracoabdominal anomalies.
  • E. Cantrell pentalogy has 5 features: supraumbilical omphalocele, sternal cleft, diaphragmatic defect, pericardial defect, cardiac anomalies; uncommon.

Flashcards

Tap a card to flip it.

What clue supports Gastroschisis?

Choose Gastroschisis when the stem gives this pattern: Gastroschisis is a paraumbilical abdominal wall defect with bowel exposed directly to amniotic fluid and not covered by peritoneum.

What clue supports Omphalocele?

Choose Omphalocele when the stem gives this contrasting pattern: Omphalocele is herniation through umbilical ring covered by peritoneum/amniotic membrane and associated with other anomalies or aneuploidy.

Quick answers

What is the fastest way to tell Gastroschisis from Omphalocele?

Gastroschisis is isolated, right-sided, and uncovered; omphalocele is midline, membrane-covered, and syndromic.

What is the key clue for Gastroschisis?

Gastroschisis is an isolated full-thickness abdominal wall defect, usually right of the umbilicus, with free-floating bowel and elevated maternal AFP.

What is the key clue for Omphalocele?

Omphalocele is midline herniation into a membrane-covered sac at the umbilical ring, raises maternal AFP, and is associated with Beckwith-Wiedemann plus trisomy 13 or 18.

What is the common trap with Gastroschisis vs Omphalocele?

Gastroschisis is uncovered bowel next to umbilicus; omphalocele is covered midline herniation through umbilical ring with anomaly risk.