Abdominal Wall Defects

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Abdominal Wall Defects

• Priscilla Joe, MD
• Childrens Hospital and Research Center at Oakland

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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-gtgiant defects containing
  liver, small and large bowel, stomach, spleen,
  ovaries, and testes
• Associated with foreshortened bowel and
  malrotation
• Small abdominal cavity and pulmonary hypoplasia

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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

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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

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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

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Gastroschisis and Omphalocele

• Combined incidence of 1 in 2000 births
• Male-to-female ratio is 1.51
• Overall survival gt 90

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Gastroschisis

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

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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

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Beckwith-Wiedemann
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Pentalogy of Cantrell
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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

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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

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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

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Mortality/Morbidity

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