Congenital Abdominal Wall Defects Gastroschisis & Omphalocele
Learning objectives
1
Define & differentiate gastroschisis vs omphalocele by sac, location, cord insertion
2
Explain embryology and etiology – vascular disruption vs failure of midgut return
3
Interpret prenatal diagnosis – USG at 18-20w + AFP, measure defect ratios
4
List associated anomalies – why omphalocele needs echo + karyotype
5
Outline resuscitation & transport – thermal, fluid, bowel protection principles
6
Discuss surgical options – primary closure vs staged silo for both lesions
40-min flow: 5 min intro + 15 min pathology/diagnosis + 15 min management + 5 min exam pearl
Overview & classification
VENTRAL WALL DEFECTS SPECTRUM
2 major
Gastroschisis & Omphalocele cause 95% of referrals
Midline
Both are failures of ventral abdominal wall closure W6-12
Key diff
Presence of sac + cord insertion + associated anomalies
1
Gastroschisis
no sac
Para-umbilical small defect, usually right, exposed bowel, normal cord insertion
2
Omphalocele
sac present
Midline central defect, herniated viscera covered by amnion + Wharton jelly + peritoneum
3
Others to remember
Umbilical cord hernia <2cm, bladder exstrophy, pentalogy of Cantrell, body stalk anomaly
4
Exam discriminator
If you see liver in sac = think giant omphalocele. If free-floating bowel = gastroschisis.
Embryology — the 4-week window that matters
Physiological midgut herniation → return → ventral wall closure. Two different failures → two diseases.
Gut outgrows cavity
Rapid liver & midgut growth → herniates into cord base. Normal physiology.
Return begins
Midgut rotates 270° counterclockwise & returns to abdomen. Abdominal folds fuse.
Gastroschisis = vascular accident
Ischemic insult to right omphalomesenteric artery → para-umbilical full-thickness defect. No sac.
Omphalocele = closure failure
Failure of lateral body folds to migrate. Gut fails to return → covered by amnion + peritoneum sac.
Normal development
Pathology
Tip: Gastroschisis RIGHT side because left umbilical vein protects left
W6
W10
G
O
Gastroschisis – definition
FULL-THICKNESS VENTRAL WALL DEFECT
Para-umbilical, usually right of umbilicus
No covering membrane – eviscerated bowel directly exposed to amniotic fluid
Umbilical cord insertion normal & separate from defect
Defect small, 2–4 cm, eviscerated bowel edematous, matted, foreshortened
Liver herniation rare – if present, think omphalocele
2–4cm
defect size
Right
90% right sided
No sac
key examiner point
WHY IT MATTERS
Exposed bowel =
Chemical peritonitis from amniotic fluid → thick peel, dysmotility, prolonged ileus after birth.
NOT covered = gastroschisis
CLINICAL CLUE
Cord separate, liver in
At delivery, bowel loops look uncovered, umbilicus intact beside defect. No sac to rupture.
Gastroschisis is a vascular disruption, not a chromosomal disease
Young mother + environmental vasoconstrictors → insult to right omphalomesenteric artery → full-thickness paraumbilical defect without sac
Risk profile
Maternal age <20y, smoking, alcohol, NSAIDs, decongestants, vasoactive drugs
Incidence 1:2000 ↑
Etiology
Vascular steal / thrombosis of right umbilical vein & omphalomesenteric artery
Mesoderm failure
Isolated lesion
70% isolated. NOT associated with trisomy. Look for bowel only, not systemic anomalies
Karyotype usually normal
Bowel association
Intestinal atresia 10-15%, stenosis, peel from amniotic fluid exposure → short gut risk
Complex = bowel loss
Omphalocele — definition
Midline ventral defect with herniated viscera covered by a membrane — cord inserts on the sac
TRILAMINAR SAC
The hallmark that defines it
Outer: Amnion
Middle: Wharton's jelly
Inner: Peritoneum
Exam tip: Cord always inserts on APEX of sac — never lateral to defect. If cord is normal beside defect → gastroschisis.
1
Midline herniation
covered
Central umbilical defect with bowel ± liver ± other organs inside membrane-covered mass
2
Variable size
Small: <4 cm contents only bowel • Large/Giant: >4 cm with liver herniation + loss of domain
3
Location spectrum
Epigastric (above cord) • Central (classic, 90%) • Hypogastric (with bladder exstrophy association)
4
Intact vs ruptured
Intact sac protects but can rupture during delivery → becomes emergency like gastroschisis, high fluid/heat loss
Omphalocele – etiology & associations
Midline failure of lateral folds to migrate W6-10 — 50-70% have systemic anomalies → always echo + karyotype
EMBRYOLOGY + INCIDENCE
1 : 4-6k
live births
Failure of gut to return + persistent central defect. Sac = amnion + Wharton jelly + peritoneum with cord at apex.
CHROMOSOMAL — 30-40%
T13, T18, T21, 45X
Trisomy 18 most common (50% of aneuploidy)
Trisomy 13, Down, Turner
HIGH-YIELD ASSOCIATION
Cardiac 30-50%
Most important for prognosis. VSD, ASD, TOF, ectopia cordis in Cantrell.
Pulmonary hypoplasia in giant
Malrotation universal
Genitourinary 20%
Exam tip: sac intact → but rupture = emergency like gastroschisis
SYNDROMES TO REMEMBER
Beckwith-Wiedemann
Macroglossia, macrosomia, hypoglycemia, hemihypertrophy — ↑ Wilms risk
Pentalogy of Cantrell
Omphalocele + lower sternum + anterior diaphragm + pericardium + cardiac defect
Gastroschisis vs omphalocele — the table
Exam question every year: sac absent vs present, cord insertion, associated anomalies, prognosis
Gastroschisis
NO SAC
LOCATION
Right para-umbilical, 2-4 cm defect
SAC
Absent — bowel free-floating, peel+
CORD
Normal insertion lateral to defect
LIVER
Rare herniation (if liver out → omphalocele)
ANOMALIES
10-20% only bowel: atresia 10-15%
PROGNOSIS
Excellent >95% if simple
Omphalocele
SAC PRESENT
LOCATION
Midline central, variable – giant >5cm
SAC
Present — amnion + Wharton + peritoneum
CORD
On sac apex — never normal
LIVER
Common in giant, loss of domain
ANOMALIES
50-70% systemic: cardiac 30-50%, T13/18/21
PROGNOSIS
Depends on anomalies, not defect size
Memory hook: Gastros = G = No sac, Gut outside, Good prognosis
Work-up: Omphalocele → fetal echo + karyotype mandatory. Gastroschisis → growth + bowel dilation follow-up
Prenatal diagnosis
Anomaly scan at 18–20 weeks is diagnostic — both elevate maternal serum AFP, differentiation is by USG
MSAFP ↑
Both lesions elevate, not specific
Timing
USG 18–20w anomaly scan gold standard, serial growth scans
Predict prognosis
Measure defect, bowel diameter, amniotic fluid index
Gastroschisis on USG
No sac
Free-floating loops, cauliflower appearance, no membrane
Defect right para-umbilical, cord insertion normal
Bowel wall thickening & dilation = poor prognostic sign
Clue: Stomach usually intra-abdominal, liver rarely outside — if liver out → suspect omphalocele
Omphalocele on USG
Sac present
Midline mass covered by membrane — cord inserts at apex
Contents: bowel ± liver — liver = giant
Look for ascites, associated anomalies in same scan
Clue: Membrane may be subtle — use color Doppler to track cord insertion to sac apex
O/D Ratios
O/AC, O/HC ratios help predict need for silo vs primary closure
Fetal Echo MUST
30-50% cardiac anomalies in omphalocele — do for all omphalocele
Karyotype in omphalocele
Amniocentesis for T13/T18/T21 — not routine in gastroschisis
Perinatal & delivery planning
No emergency C-section by default — plan delivery in tertiary center with pediatric surgery + NICU
GASTROSCHISIS
Vaginal preferred
No survival benefit with routine C-section
Induction at 37-38w debatable — balance peel vs prematurity
Exam: vaginal safe
OMPHALOCELE
C-section only if giant
<4cm + no liver → vaginal delivery OK
Giant + liver + large sac → C-section to prevent rupture, dystocia
Rupture risk → CS indicated
WHERE & WHO
Tertiary center mandatory
Delivery room ready with pediatric surgery, neonatology, anesthesia.
Counseling
Explain disease, associated anomalies, surgery, stoma risk, long stay. Psychosocial support.
NICU bed booked
Peds surgery standby
No suction on sac
PREPARATION CHECKLIST
Fetal echo + karyotype completed for omphalocele
Measure omphalocele circumference ratio
AVOID
Routine preterm delivery
Prolonged rupture of sac / bowel trauma
Neonatal resuscitation — first 15 minutes save bowel
ABCs + prevent heat, fluid, infection. Cover defect before transport — never attempt manual reduction in delivery room.
ABCDE + SUPPORT
Stabilize, decompress, protect
Airway/Breathing: mild respiratory distress from increased intra-abdominal pressure — low threshold for ventilation
NG tube: size 8Fr, continuous low suction — stomach decompresses, less bowel distension
IV access: 2 lines, 10-20ml/kg NS bolus, maintenance + replacement, Vit K, broad-spectrum antibiotics
Position: Right lateral decubitus for gastroschisis to avoid mesenteric kink; supine neutral for omphalocele
Heat loss
Exposed bowel = 4x heat loss → radiant warmer, warm saline
Fluid loss
Evaporative losses 2-3x → monitor urine, lactate
Sepsis risk
Peel + contamination → early blood culture + antibiotics
GASTROSCHISIS
Warm saline gauze + cling wrap
Moist gauze over bowel, then clear plastic wrap (bowel bag). No tight constriction. Visual monitoring.
OMPHALOCELE
Saline gauze + impervious dressing
Protect sac — do not rupture. Non-adherent dressing. Avoid hepatic vascular kink in giant.
Surgical management – gastroschisis
Goal: Return bowel safely without compartment syndrome — simple vs complex defines approach
1
Resuscitate first, surgery second
Warm saline gauze + plastic wrap, NG decompression, fluids, antibiotics, bladder pressure baseline
2
Primary fascial closure
If viscero-abdominal disproportion small → gentle reduction + primary closure. Watch PIP, bladder pressure <20 mmHg
3
Staged silo closure
Spring-loaded Silastic silo sutured to fascia, daily reduction at bedside, closure in 5-7 days— less compartment risk
4
Simple vs Complex
Simple: intact bowel | Complex: atresia 20%, perforation, necrosis, volvulus — higher mortality & LOS
5
Atresia = do not touch acutely
Bowel peel obscures atresia; if found, stoma or delayed anastomosis after bowel edema resolves (weeks)
DECISION POINT
Can abdomen close without tension?
Bladder press <20
PIP rise <20%
Urine >1 ml/kg/h
YES → Primary closure in OR
NO → Silo → gradual, NICU bedside
PRACTICAL PEARL
Wound is not peritonitis
Peel ≠ infection. Avoid aggressive peel removal → bleeding + injury. Dysmotility lasts 2-3 weeks, feeds delayed.
Surgical management — small omphalocele
PRINCIPLE
Small defect = primary closure possible if you have domain — excise sac, return gut, close fascia
Hernia of cord <1.5 cm: often looks like thick cord. Open sac carefully at edge, inspect for bowel loop adherent to cord. Ligate extra sac like hernia and close umbilical ring — cosmetic umbilicoplasty saves umbilicus.
1
Isolate sac base: Incise skin at junction, stay extra-peritoneal initially to identify liver edge and bladder dome.
2
Excise trilaminar membrane: Amnion + Wharton + peritoneum. Sharp dissection — liver capsule tears easily, bladder thin anteriorly.
3
Return & close: Reduce malrotated bowel (Ladd not routine), close fascia primarily, monitor bladder pressure & PIP.
DECISION RULE
Can we close without compartment syndrome?
Yes: Small to medium <4 cm, mostly bowel → primary fascial closure
No: Tension, PIP ↑ >20%, bladder >20 mmHg, urine drop → convert to silo / staged
Bladder <20
PIP stable
UOP >1 ml/kg/h
OPERATIVE PEARLS
Avoid sac sacrifice of liver & bladder
Liver often adherent to sac — leave thin rim of sac on capsule if needed
Bladder exstrophy association in hypogastric type — catheterize before incision
Save umbilical skin for plasty — cosmetic outcome matters
Surgical management — giant omphalocele
Defect >5 cm with liver in sac • loss of domain • cannot close primarily without compartment syndrome
THE PROBLEM
Viscera never lived in abdomen
Giant = >5cm + liver
Abdominal cavity too small, pulmonary hypoplasia risk >50%, chest too small
Loss of domain
Primary closure → ↑IAP, ↓venous return, respiratory failure, bowel ischemia
Measure
Bladder pressure, PIP, cerebral/renal perfusion. Close only if <20 mmHg
Ruptured omphalocele = emergency
Behaves like gastroschisis: wrap bowel, NG decompression, fluids, antibiotics, urgent OR
1
Staged closure — Silastic silo
Plicate sac, suture silo to fascia, daily gravity reduction 5–10 days → delayed fascial closure. Preferred when sac intact but giant.
Gradual • less ACS
2
Delayed closure — paint & wait
Escharification: Silver sulfadiazine / betadine paint sac → forms eschar → ventral hernia → definitive repair at 1–5 years
For unstable / severe PH
Definitive abdominal wall reconstruction
At 1–5y: excise sac, lyse adhesions, component separation, tissue expanders, mesh if needed. Liver adherent, bladder thin — dissect carefully.
Postoperative course & complications
Expect prolonged ileus in gastroschisis — early recognition of compartment and sepsis saves lives
FIRST WEEK PROTOCOL
Ventilation → TPN → Slow feeds
Ventilation 2-4 days
Elevated diaphragm from tight closure, avoid hypercarbia. Bladder pressure monitoring q6h
TPN mandatory
Gastroschisis dysmotility 2-3 weeks due to peel. Omphalocele smaller delay unless giant
Feeds stepwise
Trophic feeds → full when stool passed, bowel loops soft, GR low. Average 21 days gastroschisis
Red flag: Rising lactate, oliguria, increased PIP >20% → compartment syndrome → return to OR, reopen fascia or silo
GASTROSCHISIS
18.5% NEC
NEC, sepsis, short bowel
Amniotic peel predisposes. Short gut if resection + atresia / NEC totalis
OMPHALOCELE
25% Dehiscence
Compartment & wound
Increased IAP → AKI, respiratory failure. Ventral closure under tension fails — need silo or staged
GIANT OMPHALOCELE
60% Feed difficulty
GERD & dysmotility
Feeding difficulty prominent, pulmonary hypoplasia, requires fundoplication work-up later
GIANT OMPHALOCELE
43% GERD
Late morbidity
Reflux common due to small abdomen, liver traction. Needs long-term follow-up — growth, hernia, cosmesis
Long-term outcomes
Survival is excellent for simple gastroschisis — for omphalocele, cardiac & chromosomal disease drives mortality
WHAT PARENTS ASK
Will my baby be normal long-term?
Gastroschisis = mostly gut issue, growth catches up. Omphalocele = systemic disease, need multidisciplinary follow-up.
>95%
Survival simple gastroschisis
15-30%
Cryptorchidism in gastroschisis — check both testes
>50%
Pulmonary hypoplasia / HTN in giant omphalocele
1
Gastroschisis — excellent prognosis
simple
Complex (atresia, necrosis, perforation) ↓ survival to 85%, ↑ short bowel, NEC, sepsis. Most have normal neurodevelopment.
2
Omphalocele — depends on anomalies
Isolated small omphalocele: survival >90%. With aneuploidy or major cardiac defect: mortality driven by associated disease.
3
Giant omphalocele morbidities
Feeding difficulty 60%, GERD 43%, pulmonary hypertension, asthma-like symptoms. Need tissue expander / hernia care for years.
4
Growing up — cosmetics & follow-up
Umbilicus often sacrificed, later umbilicoplasty. Adhesive obstruction risk both groups. Long-term hernia & growth clinic until school age.
MBBS FINAL • HIGH YIELD
Take-home & exam tips
If you remember nothing else — remember the sac, the associations, and the first 15 minutes
Sac = omphalocele, no sac = gastroschisis
Cord on sac apex vs normal cord lateral. Liver out? Think giant omphalocele.
Omphalocele → hunt anomalies
50-70% systemic. Echo + karyotype mandatory. T13/T18/T21, cardiac 30-50%.
ABC + cover before transport
Warm saline gauze + cling wrap, NG, fluids, antibiotics, Vit K. No manual reduction in ward.
CASE VIGNETTE
36-week, right open defect, edematous bowel
Q: Diagnosis? Immediate steps? A: Gastroschisis — ABCs, prevent hypothermia/fluid loss, cover bowel with warm saline + plastic, NG decompression, right lateral to avoid kinking, IV fluids + antibiotics, transfer to tertiary NICU + pediatric surgery. Classify simple vs complex.
Survival >95%
Simple gastroschisis excellent prognosis. Feeds delayed 2-3 wks dysmotility.
Reference: Holcomb & Ashcraft's Pediatric Surgery Ch. 48 — Abdominal Wall Defects • Images for teaching only • Lecture: 40 min