Omphalocele and Gastroschisis

Symposium on Pediatric Surgery, Part I

Omphalocele and Gastroschisis LesterW. Martin, M.D.,* and A. Margarita Torres, M.D.t

Between the sixth and tenth weeks of intrauterine life, the intestine normally is herniated through a defect at the umbilicus. As the intestine lengthens, it gradually recedes into the abdominal cavity, with the colon rotating to the position that it normally assumes in postnatal life. When, for some unexplained reason, the intestine fails to return to the abdominal cavity prior to birth, the condition is referred to as an omphalocele. It is usually covered by a membrane that is continuous with the peritoneum. Small omphaloceles may contain only small intestine (Fig. 1). However, larger ones may also contain the bladder, liver, spleen, stomach, and reproductive organs (Fig. 2). If, for some reason, the sac is not intact at birth, the infant is born with a complete evisceration (Fig. 3). If the sac degenerates some time before birth, the condition is referred to as prenatal rupture of the omphalocele (Fig. 4). Exposure of the intestine to amniotic fluid induces an intehse peritoneal reaction, with edema, thickening, and sometimes heavy exudate over the surface of the intestine, usually with the loops of intestine matted firmly together. The length of time that the intestine was exposed to amniotic fluid considerably influences the length of time that will be required for normal intestinal function to return. If the intestine has not returned to the abdominal cavity, the colon is malrotated and the intestine has not completed its growth in length. The shortening of the intestine, however, is generally not sufficient, to interfere with growth and development of the infant. The associated malrotation, if left undisturbed, subsequently will become sufficiently symptomatic to require surgery in approximately 20 per cent of the patients with omphalocele. Omphalocele is estimated to occur in approximately 1 in 6000 births. An associated major congenital abnormality can be anticipated in approximately one third of infants with omphalocele. In a review of 104 infants

*Professor of Surgery and Pediatrics, Division of Pediatric Surgery, University of Cincinnati Medical Center; Director of Pediatric Surgery, Children's Hospital Medical Center, Cincinnati, Ohio tResearch Fellow in Pediatric Surgery, Division of Pediatric Surgery, Children's Hospital Medical Center; Department of Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio

Surgical Clinics of North America-Yo!. 65, No. 5, October 1985

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Figure 1. Am omphalocele containing only the small intestine. Primary repair was easily accomplished.

with ompahloceles, Smith listed the number and type of associated malformations (Table 1). 4 Considerable variation of omphaloceles is encountered clinically. A classification is significant as a guide to the method of management (Table 2). INITIAL EVALUATION AND PROPERATIVE CARE

The initial evaluation of the infant must determine the priorities of subsequent management. If the tongue is at all enlarged, the blood sugar

I

Figure 2. An omphalocele containing the intestine plus the liver. For this type of omphaloeele, it is generally necessary to open the sac and release the attachments of the protruding lobe of liver prior to closure of the defect.

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Figure 3.

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An omphalocele sac that was disrupted during delivery of the infant.

should be monitored immediately because of possible associated Beckwith's syndrome (macroglossia, omphalocele, and hypoglycemia). 1 One episode of hypoglycemia with seizure can be sufficient to result in permanent brain damage. Intravenous administration of glucose solution should be started immediately for any infant with an omphalocele, and in the event of hypoglycemia, the blood sugar can be regulated by titration of concentrated intravenous glucose. A nasogastric tube should be inserted to prevent further gastrointestinal distention by swallowed air, which would interfere with closure of the abdominal wall defect. If there is no sac covering the viscera, additional intravenous fluid will be required preoperatively because of the large surface subjected to evapo-

Figure 4. Prenatal rupture of an omphalocele. Note the thickened, edematous bowel wall and dense adhesions between loops of the intestine.

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Table 1.

W. MARTIN AND A. MARGARITA TORRES

Malformations Associated with Omphaloceles

TYPE

NUMBER

Gastrointestinal Cardiovascular Genitourinary Central nervous system Diaphragmatic Extremity deformities Ear, nose, and throat Absent sternum Pulmonary Eye Pancreas Imperforate anus Exstrophy of bladder and myelomeningocele Ileal atresia Ileal stenosis Colon atresia Incomplete jejunal wall Partial absence of segment of colon Persistent omphalomesenteric duct

18 15 15 9 6

5 5 2

1 1 1 6 5 4

1 2 1 2 2

ration of body fluids. Also, provision should be made for maintaining the infant's body heat because of evaporation from the exposed surface. If the sac is intact, one should note whether it contains viscera other than intestine, for example, the liver and spleen. The presence of the liver in the sac may complicate the repair because of angulation of the vena cava when the liver is reduced to a position beneath the abdominal muscles. The intestine, which can be visualized through the wall of the sac, should be inspected closely. The presence of both dilated bowel and tiny unused bowel suggests obstruction of the intestine. If the visualized intestine is completely collapsed and underdeveloped, it may suggest an associated atresia of the duodenum or high jejunum. The presence or absence of a xiphoid should be noted. Absence of the xiphoid suggests an associated pentalogy of Cantrell, implying associated

Table 2. I. A. B. Type II. A. B. Type Ill. A. B. C. Type IV.

Type

Clinical Varieties of Omphaloceles

Omphalocele with sac intact Containing only intestine Containing intestine plus other intra-abdominal structures Ruptured omphalocele sac Rupture of sac during delivery Prenatal rupture of sac Associated major defects Ectopia cordis Diaphragmatic hernia Exstrophy of bladder or cloaca Gastroschisis

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diaphragmatic and intracardiac defects. 2 The extreme form of the pentalogy would be associated with a bifid sternum and ectopia cordis. Cyanosis associated with an omphalocele implies either an intracardiac malformation or perhaps an associated diaphragmatic hernia. The diaphragmatic hernia in two of our patients involved the diaphragm adjacent to the pericardium. The defect of both the diaphragm and the pericardium permitted the intestine and stomach to herniate into the pericardium and surround the heart (Fig. 5). If the abdominal wall defect is remote from the umbilicus; that is, if a bridge of skin separates the umbilicus and the defect, the condition represents a true gastroschisis (Fig. 6). Gastroschisis differs from prenatal rupture of an omphalocele in that there are fewer associated malformations with gastroschisis. Otherwise, the management remains essentially the same.

Figure 5. Combined omphalocele and diaphragmatic hernia with herniation of the stomach into the pericardium.

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Figure 6.

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Gastroschisis. Note the defect remote from the umbilicus.

If the intestine has been exposed to amniotic fluid for a significant period, the wall of the intestine will be thickened and edematous, and the loops will be matted together. Because this delays peristalsis and absorption, plans should be made for parenteral alimentation during the postoperative period for 2 to 6 weeks. Insertion of a central line for parenteral alimentation, however, is deferred until3 or 4 days of age when sepsis related to the exposed intestine will cause less concern.

TREATMENT Each of the following forms of treatment has individual indications, and we have employed each throughout the years for selective patients. They are nonoperative treatment; primary closure of the entire defect, including deep fascia; closure of the skin only, leaving a fascia defect (Gross stage I) requiring closure at a later date (Gross stage II); and silastic prosthesis with staged reduction. The choice of and indications for each method of management varies with individual surgeons. The policy that we follow at Children's Hospital in Cincinnati is outlined in the following sections:

Nonoperative Treatment Over the past 27 years, we have chosen nonoperative treatment of the omphalocele in four instances in which the omphalocele was intact. Three of the infants treated nonoperatively survived, and their defects healed. One infant died of sepsis. In one instance, the infant was referred at 5 days of age. Because oflocal infection of the omphalocele sac, we elected to treat it by the exposure method, with local applications of an antiseptic. Another surviving infant had an associated respiratory distress syndrome (hyaline membrane disease) with significant respiratory distress prior to the era of

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reliable mechanical ventilation. Because we were concerned that reduction of the omphalocele would increase respiratory distress to a critical level, we elected to treat the sac nonoperatively with simple local applications of alcohol twice daily. The respiratory distress cleared, and the infant recovered. A third infant, with Beckwith's syndrome, had severe hypoglycemia. The small associated omphalocele healed with one application of tincture of Merthiolate followed by twice daily applications of alcohol. The overuse of merthiolate can result in absorption of sufficient mercury from the omphalocele membrane and cause mercury poisoning. Therefore, the use of Merthiolate should be limited to no more than three applications, after which we have found alcohol alone to be sufficient. Operative repair of the omphalocele is preferred if at all possible. Primary Repair Primary repair is generally possible if the omphalocele contains only intestine. It may be performed with either local or general anesthesia. We prefer to employ local anesthesia in order to evaluate the degree of respiratory compromise induced by the reduction of the omphalocele. Some surgeons prefer to try to repair all omphaloceles primarily with general endotracheal anesthesia followed by mechanical ventilation for several days until the abdominal musculature has relaxed sufficiently to permit weaning from the ventilator. We prefer to avoid mechanical ventilation if at all possible. Some authorities have recommended measurement of venous pressure in the lower extremity and abandonment of an attempt at primary repair of the omphalocele if venous pressure rises above a certain level. Others have suggested placing a gastrostomy tube and measuring the water pressure from it as the abdominal wall is closed. If the pressure exceeds a certain level, the attempt at primary repair should be abandoned. We have found neither of these methods reliable and, after a brief trial, have abandoned both and returned to the use of local anesthesia and clinical observation of the infant to determine whether the infant can tolerate repair without the need for mechanical ventilation. Closure of Skin Only If the infant cannot tolerate complete closure of the omphalocele but sufficient skin is available for closure, the skin can be closed over the top of the omphalocele, again with local anesthesia, and the definitive fascial repair can be deferred until the infant is 6 months to 1 year of age, at which time a ventral herniorrhaphy is performed. Operative reduction of the omphalocele may be poorly tolerated when the omphalocele contains the liver. Reduction of the abnormally shaped liver can cause displacement and angulation of the inferior vena cava and create obstruction. In this event, surgical release of the attachments of the liver to the abdominal wall is generally sufficient to prevent the acute vena caval angulation. If skin only is closed, it is preferable to use subcuticular absorbable sutures and then support the skin edges with Steri-Strips. This will permit primary healing without skin irritation and will more evenly distribute the pull on the skin edges.

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Repair of the ventral hernia is accomplished when the infant is 6 months to 1 year of age (Fig. 7). This method has been criticized because of the lack of a satisfactory method of stimulating development of the abdominal cavity to accommodate the additional viscera, which are located in the ventral hernia sac. It is important at the time of the initial operation to avoid upward dissection anterior to the thoracic cage, as this will interfere with subsequent forward growth of the thoracic cage. Any undermining should be in a lateral direction only. We have found that the best method of stimulating development of the abdominal cavity is simply to encourage the infant to sleep in the prone position, which forces the omphalocele contents into the abdominal cavity, stretches the abdominal muscles, and enlarges the abdomen. Manual reduction of the hernia with the child awake demonstrates that repair will be well tolerated. Prosthetic Reduction For the omphalocele that is sufficiently large to preclude primary repair and for which sufficient skin is not available to permit primary skin closure (Fig. BA), we have been well pleased with the method of using a Silastic silo, 3 with a sheet of Silas tic sutured to the periphery of the omphalocele fascial defect and then closed over the top as a closed sac containing all of the intestine (Fig. 8B). This is gradually reduced daily in the operating room without anesthesia. An effort is made to complete reduction by the seventh day, at which time the fascial defect can be repaired and the prosthesis removed under general anesthesia. As the viscera are forced into the abdomen, the abdominal muscles gradually stretch to accommodate the additional volume, similar to the way in which the abdomen accommodates the enlarging uterus during pregnancy.

Figure 7. This infant could not tolerate primary repair of the large omphalocele. Only skin was closed, and the fascial defect was repaired at 8 months of age.

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Figure 8. A, The large size of this omphalocele precluded even skin closure. B, Staged reduction with a Silastic prosthesis was applied to this infant. Repair was accomplished on the tenth day of life.

PARENTERAL ALIMENTATION The advent of parenteral alimentation has probably been the most significant factor influencing survival of the infants born with prenatal rupture of an omphalocele. Prior to the era of parenteral alimentation in 1965, we had 9 survivors out of 27 such infants. Since 1965, we have had 47 survivors out of 50 infants with prenatal rupture of an omphalocele. Although many other factors have influenced survival, it is our distinct impression that parenteral alimentation has been the most significant.

COMPLICATIONS Duodenal obstruction or midgut volvulus related to the associated malrotation has required subsequent operation in approximately 30 per cent of more than 200 infants with omphalocele. There was one death due to late diagnosis of midgut volvulus in an infant whose mother was an earlier member of our series. Gastroesophageal reflux has required subsequent fundoplication in nine infants. Small bowel obstruction due to adhesions has required operation in several infants during the first year of life. It is noteworthy, however, that not one patient has returned with this complication after 1 year of age.

LONG-TERM RESULTS The long-term follow-up has been incomplete, but we have been impressed with the remarkable lack of problems encountered in these children later in life. With approximately 200 survivors in our local area over a period of 27 years, late complications have been virtually nonexistent.

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REFERENCES 1. Beckwith, J. B., Wang, C. L., Donnell, G. N., et al.: Hyperplastic fetal visceromegaly with macroglossia, omphalocele, cytomegaly of adrenal fetal cortex, postnatal somatic gigantism and other abnormalities: Newly recognized syndrome. Proceedings of the American Pediatric Society. Seattle, Washington, June 16-18, 1964. 2. Cantrell, J. R., Haller, J. A., and Ravitch, M. M.: A syndrome of congenital defects involving the abdominal wall, sternum, diaphragm, pericardium and heart. Surg. Gynecol. Obstet., 107:602-614, 1958. 3. Schuster, S.: A new method for the staged repair of large omphaloceles. Surg. Gynecol. Obstet., 125:837--839, 1967. 4. Smith, W. R., and Leix, I.: Omphalocele. Am. J. Surg., 111:450--455, 1966. Children's Hospital Medical Center 240 Bethesda Avenue Cincinnati, Ohio 45229