Abdominal Wall Defects

1. Abdominal Wall Defects Priscilla Joe, MD Children’s Hospital and Research Center at Oakland

6. Omphalocele • Membrane sac arising from the umbilical cord covers intestines • Outer membrane layer consists of amnion and inner lining of peritoneum • Size ranging from small->giant defects containing liver, small and large bowel, stomach, spleen, ovaries, and testes • Associated with foreshortened bowel and malrotation • Small abdominal cavity and pulmonary hypoplasia

8. Gastroschisis • No membrane covering • Abdominal wall defect typically 2-4cm diameter • Lateral to the right side of the umbilical cord • Usually contains midgut and stomach • Thickened, atretic, and possibly ischemic bowel • Associated with malrotation

9. Embryology of Gastroschisis • Failure of vascularization of the abdominal wall due to abnormal involution of the right umbilical vein or a vascular accident of omphalomesenteric artery causes abdominal wall weakness and subsequent rupture • Rupture of a small omphalocele with absorption of the sac and growth of a skin bridge between the abdominal wall defect and umbilical cord

10. Embryology of Omphalocele • Normally, midgut returns to the abdomen by 10th week of gestation • Somatic layers of cephalic, caudal, and lateral folds join to close abdominal wall • With omphalocele, folds fail to close

11. Gastroschisis and Omphalocele • Combined incidence of 1 in 2000 births • Male-to-female ratio is 1.5:1 • Overall survival > 90%

12. Gastroschisis • Increasing incidence • Associated with young maternal age and low gravida • Associated with prematurity and low birth weights

13. Omphalocele • Incidence has remained constant • Increased risk with advanced maternal age • Probable genetic predisposition • Associated syndromes and anomalies (45-55%): - gastrointestinal - cardiac - trisomy 13, 18, 21 - OEIS complex (omphalocele, bladder extrophy, imperforate anus, spinal defects - Beckwith-Wiedemann - pentalogy of Cantrell - cleft palate - pulmonary hypoplasia • May be associated with maternal use of valproic acid

14. Beckwith-Wiedemann

15. Pentalogy of Cantrell

16. Diagnosis • AFP synthesized in fetal liver and excreted by fetal kidneys and crosses placenta by 12 weeks • Elevated maternal MSAFP in neural tube defects, abdominal wall defects, duodenal or esophageal atresia • 40% false positive rate • Fetal ultrasound after 14 weeks gestation • Amniocentesis and fetal echocardiography

17. Treatment • NGT to low intermittent suction • Use of bowel bags, saran wrap • Conservation of body heat and fluid losses • Antibiotics • Careful positioning to avoid kinking of mesenteric vessels • 1.5 times maintenance fluids with isotonic fluids

18. Surgical Management • Operative repair within 2-4 hours of birth • Primary closure for smaller defects • Delayed primary closure for large defects • Avoid compromised ventilation and abdominal compartment syndrome • Use of silo with sequential reduction of abdominal contents • Later fascial closure

20. Mortality/Morbidity • Short gut syndrome • NEC • Gut dysmotility and prolonged ileus • Sepsis • Complications from associated anomalies/syndromes