Pediatric Omphalocele and Gastroschisis (Abdominal Wall Defects) Treatment & Management

Transfer

When transferring infants with ventral abdominal body wall defects, covering the intestines with warm, moist lap pads seems reasonable, but the heat is soon dissipated. A better approach is to:

• Cover the intestines with a nonadherent, semi-permeable membrane (eg, plastic cling wrap such as Saran Wrap). Then,
• Wrap dry Kerlex dressing around the intestines, including the infant's torso, so that the intestines are situated just above the abdominal wall defect. Then,
• Place the infant in a bowel bag.

This technique minimizes the loss of heat and moisture from the exposed intestines, as well as protects the mesentery from twisting or stretching. ^[22] A radiant warmer should only be used if the intestines are protected.

Intravenous fluids are administered to counter evaporative and third space (GI tract) losses; an orogastric tube is placed to prevent gastric distention from swallowed air. Antibiotics are indicated, in view of the open peritoneal cavity and exposed bowel.

Drug therapy

Drug therapy is determined by the exigencies of caring for an ill premature baby.

Omphalocele

Intestines within an intact omphalocele are protected from the amniotic fluid; hence, these babies tolerate feedings promptly after the abdominal wall defect is closed. Infants with giant omphaloceles, however, usually require prolonged hospitalization. Because their respiratory reserve is limited, reduction and closure in these babies should be accomplished gradually. "Paint and wait" is perhaps the safest approach: Topical antimicrobials are applied to the omphalocele membrane, and the infant's torso is wrapped with an elastic bandage (eg, ACE bandage). Healing occurs by epithelialization and wound contracture. These babies may require ventilatory assistance and tracheostomies.

Gastroschisis

If the appearance of the intestines is normal in an infant with gastroschisis, reduction and closure are usually feasible. A relatively recently proposed technique is "sutureless closure," in which, following reduction of the eviscerated bowel, the umbilical cord is used to fill the opening in the abdominal wall and then is secured in place with an adhesive dressing.

If the intestines are inflamed and abdominal wall closure is not possible, the intestines are placed within a silo and reduction is accomplished over the subsequent 7-10 days.

Parenteral nutrition allows for continued growth and healing; intestinal recovery is signaled by the passage of "starvation stools." If intestinal function is delayed beyond 4-6 weeks, a contrast bowel study should be obtained to assess transit of contrast medium through the intestines. If this study demonstrates a mechanical obstruction, laparotomy is indicated.

Intestinal inflammation

Intestinal inflammation may occur in the setting of gastroschisis or ruptured omphaloceles.

The intestines may be pristine, as in a fresh laparotomy, or they may be stiff and edematous, matted together, and covered by an inflammatory “peel.” Appearance predicts function: In the first setting, infants tolerate feedings promptly, whereas injury from amniotic fluid exposure or ischemia is associated with intestinal dysmotility and malabsorption. Histologic evaluation shows atrophy of myenteric ganglion cells and mucosa. The injury usually heals as the baby grows, as long as adequate parenteral nutrition is provided.

Intact omphalocele

Infants with intact omphaloceles are usually not distressed; however, they should be carefully screened for associated problems, such as Beckwith-Wiedemann syndrome (which may cause hypoglycemia) or congenital heart disease, genetic abnormalities, or other malformations.

Maintenance intravenous (IV) fluids are administered, and the intact omphalocele sac is covered with a nonadherent dressing, such as Xeroform or Saran Wrap to preserve body heat and moisture.

Prophylactic antibiotics may be given preoperatively, if surgery for an associated intestinal anomaly is anticipated..

Closure of a small or moderate-sized omphalocele is usually accomplished without difficulty; however, infants with giant omphaloceles require staged surgery or "paint and wait", a nonoperative technique whereby topical antimicrobials are applied to the omphalocele sac (bacitracin or mupirocin), and the baby's torso is wrapped with an elastic bandage. This approach relies upon epithelialization of the omphalocele sac and wound contracture to obliterate the abdominal wall defect.

Ruptured omphalocele

When the omphalocele membrane is ruptured, the extruded viscera are placed in a silo, as with the case of gastroschisis. ^[28]

If a giant omphalocele is ruptured, it may be best to obtain closure utilizing biologic mesh (Alloderm or Surgisis) ^[39] sutured to the fascial margins of the defect. (See the image below.)

Closure of giant omphaloceles containing the liver is always challenging. ^{[40, 41, 42]} See the following images.

Gastroschisis

If the stomach is distended (from swallowed air), an orogastric tube should be placed to evacuate the air and succus intericus ("intestinal juice").

The eviscerated intestine should be placed over the abdominal wall defect, covered by Saran Wrap, and wrapped with dry Kerlix; the infant's lower torso may then be placed in a bowel bag. The baby may be placed in an incubator or under a radiant warmer, as long as the bowel is protected.

Administer broad-spectrum antibiotics because of the exposed intestine and open peritoneal cavity.

Anticipate and correct fluid, electrolyte, and heat losses: Administer an IV fluid bolus (20 mL/kg lactated Ringer or normal saline), followed by 5% dextrose/0.45 normal saline with potassium chloride (after having established the infant's urine output). Usually the baby's fluid requirements are greater than maintenance because of evaporative and third-space losses (within the lumen of the gut and interstitial tissues). Clinicians must carefully balance intake (IV fluids) and output (urine and gastrointestinal losses).

Urine output provides the most accurate measure of the adequacy of fluid resuscitation. Blood gas analysis identifies hypoperfusion and/or inadequate ventilation. Reduction of the herniated viscera is facilitated by evacuating meconium from the sigmoid colon and rectum.

Place a central venous line to provide parenteral nutrition, thereby minimizing catabolic protein loss during the period of gastrointestinal dysfunction. ^{[33, 34, 35]}

Consultations

Neonatologists and pediatric surgeons share the responsibility for the treatment of babies with abdominal wall defects.

Consultation with a cardiologist, pulmonologist, gastroenterologist, and geneticist may be indicated.

Midgut volvulus

A multi-institutional retrospective study identified 115 infants with omphalocele and 299 with gastroschisis, during the years 2000-2008. ^[43] Midgut volvulus occurred in 8 cases overall: 5 omphalocele babies and 3 gastroschisis babies. These authors advocate a Ladd procedure, concomitant with repair of an omphalocele. ^[43]

Omphalocele

Ambrose Pare, a 17th-century French surgeon, accurately described the adverse consequences of opening the omphalocele sac during closure of the abdominal wall defect. ^[44] He advocated squeezing the sac to reduce the herniated viscera and, if reduction was not possible, painting the sac with escharotic agents to promote epithelialization and wound contracture. However, healing is slow utilizing this technique, and during this time, the sac may rupture and the infant succumb to infection.

Healing is hastened by mobilizing skin flaps to cover the omphalocele sac (Gross technique); however, this results in the creation of a large ventral hernia.

In 1967, Schuster developed a more expeditious technique to close giant omphaloceles and large ventral hernias. ^[45] A circumferential incision is made along the perimeter of the omphalocele, leaving the sac intact to protect the herniated viscera. The incision is extended in the midline, exposing the rectus fascia from xiphoid to pubis. Silon (Teflon-reinforced Silastic) sheets are sutured to the rectus muscles and approximated in the midline over the omphalocele sac. Reduction is effected by gradually approximating the Silon sheets, which pulls the rectus muscles over the liver and intestines. When the ventral bulge is leveled, the Silon sheets are removed with the omphalocele sac; permanent closure is obtained by approximating the rectus fascia or sewing an elliptical patch to the fascia and then covering the patch with skin flaps. If this is not feasible, biologic mesh may be placed over the liver and intestines. Ultimately, the patch will be vascularized and support the ingrowth of epithelial cells. (See the image below.)

The use of a rigid patch is preferable (Gore-Tex, Surgisis). ^[39] The ellipse is tailored to give the anterior abdominal wall a concave appearance, lessening pressure upon the diaphragm. The patch is attached to the defect circumferentially: superiorly to the costal arch, inferiorly to the pubis, and laterally to the rectus fascia. Inflation of the lungs elevates the costal arch, which expands both the chest and the abdomen; the increased intra-abdominal pressure stretches the rectus muscles and stimulates their growth.

Dr Russell Jennings of Boston's Children's Hospital has developed an innovative technique whereby upward traction is applied to the silo housing the extruded viscera. The silo is firmly attached (sewn) to the circumference of the abdominal wall defect, and excess skin is attached to the silo. Upward traction stimulates growth of the abdominal wall over the extruded viscera, as opposed to pushing the extruded viscera into an undersized abdominal cavity. ^[46] (See the following images.)

Synthetic patches (Gore-Tex) require skin coverage or they will ultimately be rejected. Biologic mesh (Alloderm, acellular human dermis; or Surgisis, intestinal submucosa) provides a scaffold for ingrowth of autogenous cells; hence, the body does not perceive them as foreign, and they are not as prone to infection and rejection. Alloderm stretches, and the ultimate result is a large, but epithelialized protrusion that ultimately will require repair. ^{[47, 48]}

“Component separation” is a technique pioneered in adult patients to repair ventral hernias. Bilateral incisions are made along the Spigelian line (semilunar line) to allow medial displacement of the rectus fascia and closure of the abdominal wall defect. More recently, this technique has been utilized in children. ^[49]

See the images below.

Gastroschisis

In 1969, Allen and Wrenn adapted Schuster's technique to gastroschisis. ^[50] Silon (Dacron-reinforced Silastic) sheets are sutured to the full thickness of the abdominal wall defect and closed over the eviscerated intestine, creating a silo. Reduction is facilitated by stretching the abdominal musculature, emptying the stomach and bladder, and manually evacuating the colon. The silo is gently squeezed each day; usually a week is required to effect reduction of the extruded viscera. The critical factor is resolution of inflammation; in time, the stiff, congealed intestines become normal—soft and pliable—and can fit into the nooks and crannies of the abdominal cavity. ^{[51, 52]}

Adhesions may develop between the intestines and the silo or the abdominal wall defect. For this reason, Dr Jennings advocates applying Seprafilm over the intestines before placing the silo. ^[46]

Excessively tight closure of the abdominal cavity causes increased intra-abdominal pressure (abdominal compartment syndrome), which limits diaphragmatic excursion, impairing ventilation. Increased peak inspiratory pressure (PIP) is required, but this will decrease venous return. Increased heart rate is required to maintain cardiac output. If renal blood flow diminishes, glomerular filtration rate will also decrease, and urine output will fall; renal failure or renal vein thrombosis may ensue. Diminished mesenteric blood flow causes ischemia and augments the risk of necrotizing enterocolitis (NEC), because dysmotility leads to stagnation and bacterial overgrowth, and the bowel is immunologically immature. ^[53]

Avoid PIPs greater than 25 mm Hg. High-frequency oscillatory ventilation is an alternative to conventional ventilation, if intra-abdominal pressures are markedly increased. ^[54]

The intra-abdominal pressure is measured by connecting a manometer to a Foley catheter or a nasogastric tube. The central venous pressure, intravesical pressure, and the intragastric pressure should not exceed 20 cm H₂O to avoid development of abdominal compartment syndrome. ^[24]

Alternate ways of managing infants with abdominal wall defects generate lively discussion among colleagues. When disparate techniques yield equivalent results, when no technique is demonstrably superior, personal preference is determinative.

The dilemma is balancing the goal of replacing the extruded viscera and closing the abdomen against the attendant complications, most notably abdominal compartment syndrome, which follows the degree of viscera-abdominal disproportion. Minimizing intra-abdominal hypertension (IAH) is critical.

An intra-abdominal pressure above 15 mm Hg is high; that exceeding 20 mm Hg is excessive and likely to precipitate abdominal compartment syndrome. The effects of IAH are both hemodynamic and ventilatory. Reduced cardiac output diminishes splanchnic and renal perfusion, which leads to oliguria and gut acidosis. Hypoventilation (hypercarbia and hypoxia) compounds the metabolic acidosis. Abdominal compartment syndrome has devastating physiologic complications, including renal failure, sepsis, bowel ischemia, and wound complications.

Bowel ischemia leads to NEC, which may cause short-bowel syndrome. Wound complications include dehiscence, sepsis, and enterocutaneous fistulae. Excessively tight closure of gastroschisis may be a factor in as many as 75% of patients referred for intestinal transplantation. ^[55]

Controversial issues include the following:

• Should these infants be delivered by cesarean delivery or vaginally?

• Should a prefabricated silo be placed in the neonatal intensive care unit (NICU) with sedation, or in the operating room (OR) under general anesthesia? Does it matter?

• Can the intestines be more thoroughly cleansed and the anatomy better assessed in the OR rather than in the NICU?

• Are "off the shelf" silos preferable to those fabricated by the surgeon from Silon sheets?

• Does stretching the flaccid (paralyzed) abdominal wall enlarge the abdominal cavity?

• Is enterolysis of the inflamed intestine, cutting through the inflammatory peel and separating the congealed loops of intestine feasible, or is the risk of damaging the intestine prohibitive?

• Should an attempt be made to evacuate meconium from the intestine?

• Does squeezing the intestine injure the serosa and promote the formation of adhesions?

• Should the appendix be removed and the opening in the cecum used to evacuate the meconium?

• Should the surgeon dilate the anus and milk the meconium through the colon into the rectum and out the anal canal?

• If a silo is placed, should pressure be applied to the eviscerated intestine, and does this pressure enlarge the abdominal cavity as opposed to the Jennings approach?

• Is resolution of inflammation the determinative factor in achieving reduction? Is squeezing the silo necessary? Simply allowing the intestine to sink by gravity into the abdominal cavity may be sufficient.

• When should a silo be removed to minimize the risk of infection?

• Which antibiotics should be used?

• Should the antibiotic cover gut or skin flora?

Many surgeons favor placement of a prefabricated silo in the nursery with gradual reduction of the extruded intestine. Criteria that preclude this technique include poor bowel perfusion (a small, constricting defect), or bowel and/or mesentery attached to the abdominal wall defect, gross viscera-abdominal disproportion, and deteriorating metabolic acidosis. ^{[55, 56]}

Vigilance is necessary during reduction to ensure that the intestines are actually moving into the peritoneal cavity as the silo is squeezed. Otherwise, bowel loops may be compacted together or pressed against the ring of the silo or the margins of the defect, causing congestion or ischemia. Any sign of venous congestion mandates removal of the silo and inspection of the intestines. Necrosis of the duodenum from the ring of the silo abutting its anterior wall has been reported. ^[56] (See the image below.)

The baby in the image above is truly remarkable. She was born with jejunal atresia and necrosis of the distal small intestine and necrosis of the antimesenteric aspect of the atretic jejunum. This was excised, and the remaining intestine was tubularized. Ultimately, it became dilated; we utilized the serial transverse enteroplasty (STEP) procedure ^[57] and created an anastomosis to the distal microcolon. Anastomotic stricture occurred and required several revisions, but each time the proximal intestine dilated, making it amenable to additional STEP procedures. This infant was referred for an intestinal transplantation, which proved to not be necessary.

See the images below.

Bladder exstrophy

Surgical repair of bladder exstrophy aims to preserve kidney function. Surgical reconstruction involves the following:

• The bladder is dissected away from its attachments to the lower abdominal wall and folded upon itself.

• Closure of the lower abdominal wall defect necessitates creating a space for the bladder and other pelvic organs.

• The shape of the pelvis must be altered, from flat and shallow to concave.

• The intersymphyseal band between the splayed pubic symphysis is divided, and the anterolateral pelvic bones are rotated medially. If left untreated, affected children have a waddling gait because of the "down-and-out" rotation of the anterior pelvic ring and diastasis of the pubic symphysis.

• Urinary continence and voluntary micturition is obtained by early closure of the bladder and reconstruction of the bladder neck and urethra.

• Vesicoureteral reflux is usually present and requires antibiotics and, perhaps, ureteral reimplantation.

• Finally, epispadias is corrected, to achieve adequate genitourinary function.

See the images below.

Prune-belly syndrome

Operative procedures to correct prune-belly syndrome include the following:

• Reconstruction of the abdominal wall (especially the lower portion)

• Repair of the urinary collecting system (megaureters and megacystis)

• Performance of bilateral orchiopexies

Cloacal exstrophy

Repair of cloacal exstrophy includes the following:

• Reduction of the prolapsed ileum (the "elephant trunk")

• Separation of the flayed-open cecum from the central portion of the bifid bladder; this placode of cecum is tubularized

• Approximation and repair of the bladder halves as in bladder exstrophy

• Later, mobilization and anastomosis of the colostomy to the rudimentary hind gut and creation of a stoma; or an anus may be reconstructed by posterior sagittal anorectoplasty ^[58]

See the images below.

Diet

Infants with omphaloceles have normal intestine and do not require special formulas. The occasional intestinal atresia, perhaps associated with a patent omphalomesenteric duct, is not usually associated with short gut.

Those with gastroschisis, however, may have sustained injury to the intestine and thus may require elemental formulas or protein hydrolysates with lactose-free carbohydrates, or medium-chain triglycerides.

Babies with short-gut syndrome absorb medium-chain triglycerides more readily than long-chain triglycerides; paradoxically, the latter are more valuable with regard to gut adaptation.

Activity

The liver of a child with a repaired giant omphalocele is located in the epigastrium, where it is more vulnerable to trauma. Therefore, these children should avoid contact sports.

Following discharge, these infants require close follow-up to assess their growth and weight gain, and to chronicle developmental milestones.

They frequently have symptoms of gastroesophageal reflux (GER), which are notoriously variable, and which may occasionally be life-threatening. Treatment for GER follows the same principles as for other infants.

Hirschsprung disease may also occur. Physicians should consider this diagnosis in a child with refractory constipation and failure to thrive.