Learning objectives

• Describe the difference between omphalocele and gastroschisis
• Anesthetic management of pediatric patients with abdominal wall defects

Definition and mechanisms

• Omphalocele and gastroschisis are congenital abdominal wall defects resulting in intestinal herniation from the abdominal cavity
• Resulting from major defects in the closure of the abdominal wall → exposure of abdominal viscera
• Main difference: There is no sac covering the intestines in gastroschisis
• Both can be detected antenatally using fetal ultrasound → allows timing, location, and mode of delivery to be planned in advance
  • Omphalocele: Deliver at term
  • Gastroschisis: Benefit from early delivery (37 weeks gestation) to limit bowel damage from exposure to amniotic fluid
• Both are associated with prematurity and low birth weight

Omphalocele

• Herniation of abdominal contents through the middle of the abdominal wall at the umbilicus
  • The skin, muscle, and fibrous tissue are missing
  • The intestines herniate through the opening and are covered by a thin sac
  • The sac is formed from an outpouching of the peritoneum and protrudes in the midline, through the umbilicus
• Commonly occurs with other congenital defects (e.g., heart and kidney defects), chromosome abnormalities (e.g., Down syndrome, trisomy 18, trisomy 13), and genetic syndromes (e.g., Beckwith-Wiedemann syndrome)

Gastroschisis

• Herniation of abdominal contents from a defect lateral to the umbilicus (usually right-sided), but not directly over it
• Protruding organs are not covered by a thin sac → damage due to direct contact with amniotic fluid in the uterus → inflammation
• Rarely have other congenital defects, seldom associated with chromosome abnormalities or genetic syndromes

Signs and symptoms

• External herniation of abdominal viscera

Omphalocele

• Omphalocele minor: Minor herniation into the umbilical cord, small 5-8 cm defect 
• Omphalocele major: Large defect, including the liver, with poorly developed abdominal and pulmonary hypoplasia
• Intestine looks normal

Gastroschisis

• The intestine wall may be thickened, with a fibrin “peel” due to exposure to amniotic fluid
• May involve the stomach, bladder, uterus, and rarely liver

Complications

• Intrauterine growth retardation
• Underdevelopment of the lungs → respiratory insufficiency may require mechanical ventilation
• Feeding difficulties
• Poor gut motility
• Malrotation
• Intestinal atresia
• Volvulus
• Stenosis
• Gastroesophageal reflux
• Short bowel syndrome → dehydration

Sequelae of an open abdomen

• Aspiration
• Hypothermia
• Fluid and electrolyte abnormalities
• Sepsis

Treatment

Initial post-delivery treatment

• Fluid resuscitation
• Care of herniated bowel/viscera and their blood supply: Cover exposed organs with a sterile dressing to keep them moist and protected
• Bowel decompression using a nasogastric tube
• Temperature regulation: Nurse in an incubator to reduce heat loss
• Omphalocele: Inspect the sac to check whether or not it is ruptured
• IV antibiotics to minimize the risk of infection

Single vs staged surgery

• Surgery typically takes place shortly after birth
• Omphalocele: Semi-urgent surgery unless sac is ruptured
• Gastroschisis: Urgent surgery
• Required to replace the intestines in the abdomen and to close the opening
• Single stage surgery: Omphalocele minor
  • Intestines are moved back in the abdomen, and the opening is closed during the same surgery
• Staged surgery: Omphalocele major and gastroschisis
  • Wrap intestines in a protective covering (i.e., silo)
  • Gradually move intestines back into the abdomen over several days or weeks
  • Surgically close the opening once all intestines are back in the abdomen

Management

Keep in mind

• Neonates are highly susceptible to dehydration and heat loss before repair of the abdominal wall defect → fluid resuscitation and temperature control
• Repair surgery may be primary or staged
• Improved survival is associated with optimal pre- and postoperative care

Suggested reading

• Saraiya NR. GASTROSCHISIS AND OMPHALOCELE. In: Houck PJ, Haché M, Sun LS. eds. Handbook of Pediatric Anesthesia. McGraw Hill; 2015. Accessed February 14, 2023. https://accessanesthesiology.mhmedical.com/content.aspx?bookid=1189&sectionid=70363342 
• Poddar R, Hartley L. Exomphalos and gastroschisis. Continuing Education in Anaesthesia Critical Care & Pain. 2009;9(2):48-51.
• Wouters K, Walker I. Neonatal anaesthesia 2: Anaesthesia for neonates with abdominal wall defects. WFSA. August 28, 2008. Accessed February 14, 2023. https://resources.wfsahq.org/atotw/neonatal-anaesthesia-2-anaesthesia-for-neonates-with-abdominal-wall-defects/