CHAPTER 25 Gastroschisis and Omphalocele
Step 1: Surgical Anatomy
♦ Gastroschisis results from an anterior abdominal wall defect with herniation of the abdominal viscera into the amniotic sac. The defect is always to the right of the umbilicus and is generally 2 to 3 cm in diameter (Fig. 25-1).
♦ Omphalocele is a consequence of a central abdominal wall defect, which unless ruptured, is covered by a membrane. These defects can be small (1 to 2 cm), also referred to as hernias of the cord, or large and involving most of the abdominal wall and including the liver. Defects can be seen with associated cloacal exstrophy and also with sternal defects, such as in the case of pentalogy of Cantrell (Fig. 25-2).
Step 2: Preoperative Considerations
Gastroschisis
♦ Infants born with gastroschisis are often premature and are more likely than those with omphaloceles to have an associated intestinal atresia (14% vs. 1%). Although association with other significant abnormalities is uncommon, careful evaluation of the newborn is necessary.
♦ Initial assessment of the bowel is essential to ensure adequate perfusion without volvulus. Placing the infant in a lateral position can be helpful in preventing the mesentery from kinking as the bowel exits the abdomen.
♦ The infant should be placed in a “organ bag” with warm normal saline to protect the bowel and minimize evaporative fluid loss (Fig. 25-3).
Omphalocele
♦ Infants with omphalocele frequently have associated anomalies (cardiac and renal), chromosome abnormalities (trisomy 13-15 or 16-18), or recognizable associated syndromes (Beckwith-Wiedemann, pentalogy of Cantrell, caudal regression).
Step 3: Operative Management
Gastroschisis
♦ During preparation and prepping, care should be taken to maintain the infant’s temperature by using both a warm operating room and, when possible, warm prep solutions.
♦ Once the infant is prepped, a finger can gently be placed into the defect to ensure no bands or adhesions are present to the undersurface of the fascia. At this point the fascia and abdominal wall can be gently stretched.
♦ The bowel should be examined for obvious perforations or atresias; however, no attempt should be made to mobilize matted bowel. If a perforation is identified, the area should be ligated or sutured closed without attempts to perform an anastomosis in the face of matted abnormal bowel.
♦ Circumferential skin flaps should then be made to identify the fascia. If the defect is small, it is sometimes necessary to extend the fascial opening in the midline to return the bowel to the abdominal cavity more easily.
♦ Once the bowel is gently reduced, the fascia can be closed with interrupted 3-0 absorbable sutures. At the time of tying the sutures, the surgeon should communicate carefully with the anesthesiologist to ensure that there has not been a significant change in peak inspiratory pressures or a loss of tidal volume secondary to increased intra-abdominal pressure.
♦ If there is any ventilatory compromise or the abdomen feels tight to the surgeon, the abdomen should be left open and a silo placed to allow for delayed closure. Once the fascia has been successfully closed, the skin should be closed with subcuticular sutures, and attempts can be made to save the umbilical cord to allow for a more normal-appearing umbilicus.
♦ Infants whose abdominal wall cannot be safely closed primarily should have a temporary silo placed. In many institutions, this can be performed in the nursery with sedation. The simplest approach is by using a prefabricated silo (Bentec Medical, Woodland, CA). These silos are available in multiple sizes based on the diameter of the defect. The bowel is gently placed into the silo, and the spring loaded ring is gently placed beneath the fascial edge (Fig. 25-4, A). Occasionally the fascia defect will need to be extended before placing the silo. Once the silo is in place, it is suspended in a vertical orientation to allow the bowel to be supported and gravity to assist in the reduction (Fig. 25-4, B). The bowel can then be manually reduced in the silo on a daily basis as tolerated by the infant (Fig. 25-4, C).
♦ Alternatively, a handmade silo can be created using Silastic sheeting sewn to the fascial edges and suspended in a vertical fashion. These silos are managed similarly to prefabricated ones, where they are reduced daily as tolerated to return the bowel to the intra-abdominal domain.
♦ Once the bowel is reduced to the level of the abdominal wall, the infant should be taken to the operating room for surgical closure of the fascia. As with the primary closure, the fascial edges should be identified and freed from adhesions on the intra-abdominal side. In addition, broad skin flaps may be necessary to ensure a tension-free closure. Fascia should be closed using interrupted sutures. After ensuring adequate hemostasis of the flaps, the skin can be closed with a subcuticular stitch. If the umbilical cord stump is not suitable for closure at this point, an umbilicoplasty can be performed using two sequential purse-string sutures to recreate an “umbilicus” (Fig. 25-5).
Omphalocele
♦ For small to moderate-sized omphaloceles, primary closure is often possible. After appropriate preoperative evaluation, the infant can be taken to the operating room. The sac is sharply removed circumferentially, taking care to identify and ligate the umbilical vessels (Fig. 25-6). The abdominal cavity can then be gently explored and the fascial edges identified. Skin flaps can also be elevated as needed.
♦ For larger hernias or in infants with other complex malformations, delayed closure may be required. Options for these children include desiccation with subsequent granulation of the membrane, skin closure only (Fig. 25-7), or creation of a silo with subsequent reduction similar to that described for gastroschisis.
♦ Following skin closure only, either as a primary approach or after attempted reduction, a large ventral hernia is often present (Fig. 25-8).
♦ At the time of delayed repair of these ventral hernias, it is crucial to be aware that the hepatic veins may be located quite superficially as a result of the abnormal position of the herniated liver (Fig. 25-9).
Step 4: Postoperative Care
♦ Nasogastric decompression is necessary until there are signs of bowel function. Nutrition support should be provided either via a peripherally placed intravenous central catheter or a tunneled central venous catheter. In gastroschisis, clinical evidence of bowel function and tolerance of full feeds can take from 2 to 6 weeks from closure. Infants with omphalocele generally have earlier demonstration of bowel function and in general have fewer motility abnormalities.
Step 5: Pearls and Pitfalls
♦ Following gastroschisis closure, bowel motility can be slow to recover and may be abnormal. Patience with the institution of feeds and the slow advancement of continuous feeds is necessary.
♦ Intestinal atresias in association with gastroschisis may be identified at the time of bowel inspection or detected later only after the institution of feeds. Generally, repair of atresias should be attempted about 6 weeks after initial closure. During the intervening time, the infant should have continuous nasogastric decompression and receive parenteral nutrition.
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