Omphalocele

What is an Omphalocele

Omphalocele is a type of birth defect that happens when a developing baby’s stomach muscles do not close around the growing intestines and abdominal organs.

This usually occurs around the 11th week of pregnancy. If your baby has this condition, the intestines and some abdominal organs are outside the abdomen in a thin sac of see-through tissue.

Babies who are born with this condition often have other birth defects as well. Surgery is needed to put the organs back inside the abdomen.

9 Interesting Facts of Omphalocele

1. Omphalocele (exomphalos) is a congenital midline abdominal wall defect in which neonates are born with variable amount of intestine and often other organs (eg, liver) herniated outside the abdominal wall 
   • Herniated viscera is covered by a membrane, unless it has ruptured in utero
   • Defect is most commonly centered in the mid-abdomen; may be centered in the upper or lower abdomen
   • Umbilical vessels insert directly into the membrane instead of the intact body wall
2. Neonates with omphalocele often present with other associated major physical and/or chromosomal abnormalities
3. Most defects are diagnosed prenatally through routine screening studies such as prenatal ultrasonography and elevation in maternal α-fetoprotein level
4. Prenatal diagnosis allows for early consultation with team (eg, pediatric surgeon, high-risk obstetrician, neonatologist) with expertise managing patients pregnant with fetuses with abdominal wall defects and the fetuses/neonates themselves
5. Delivery goal for most patients is term vaginal delivery, unless fetal or maternal obstetric indications dictate need for cesarean section
6. Initial focus of neonatal management is on effective neonatal resuscitation and stabilization followed by protection of exposed viscera from injury and fluid and heat loss
7. Definitive surgical management involves reducing viscera to intraperitoneal location and closing fascia and skin while minimizing risk of additional injury to vital organs
   • Many techniques are available for definitive surgical management depending on size of defect, condition of bowel, and size and stability of neonate
   • Nonoperative escharotic therapy with delayed repair months later is a common approach
   • Immediate primary reduction and closure of open abdominal wall defects (ie, ruptured omphalocele) is preferred when neonate is stable and reduction is not likely to result in abdominal compartment syndrome
   • Staged procedure may be required for some patients
8. Overall mortality for survivors born with omphalocele is considerably higher (up to 30%) than those with gastroschisis (up to 5%) 
9. Long-term prognosis for patients with omphalocele is largely dependent on presence and severity of comorbid associated major congenital anomalies and/or chromosomal abnormalities

What are the causes?

This condition occurs when the muscles of the abdominal wall of a developing fetus do not close properly during pregnancy.

What increases the risk?

A baby is more likely to develop this condition if:

• The mother is relatively young or old.
• The mother is overweight.
• The mother used in vitro fertilization to become pregnant.
• There is a family history of omphalocele.
• The mother does any of the following during pregnancy:
  • Smokes.
  • Uses alcohol.

What are the symptoms?

The only sign of this condition is the sac of abdominal organs outside the abdomen. If the sac is broken or leaking, there may also be signs of infection.

How is this diagnosed?

This condition may be diagnosed during pregnancy or at birth. Sometimes, this defect is found during a routine prenatal exam, such as an ultrasound or blood test.

At birth, an omphalocele can be seen sticking out of the abdomen right away. Your health care provider will make sure that the sac is not leaking and will check whether the organs inside the sac are healthy.

How is this treated?

Surgery to put the organs back inside the abdomen is the only treatment for this condition. Surgery may be done before your child leaves the hospital. This depends on the size of the omphalocele and whether your child has any other problems. A small omphalocele may simply be put back inside the abdomen right away. A large one may need to be repaired in stages.

Summary

• An omphalocele is a birth defect in which a baby’s intestines and some abdominal organs are outside the abdomen in a thin sac.
• Babies with an omphalocele sometimes have other birth defects or syndromes.
• The only treatment for an omphalocele is surgery to put the sac and organs back inside the abdomen, and to eventually close the hole in the abdomen. This may take one or many surgeries, depending on how large the hole is.

Additional Info on Omphalocele

Pitfalls

• Fluid losses in neonates with abdominal wall defects (especially exposed bowel) are significant; these neonates often require 2 to 3 times usual maintenance fluids. Carefully monitor fluid status (eg, urine output, perfusion, vital signs) in the immediate neonatal period
• Prenatal ultrasonography cannot reliably confirm abdominal wall defects until about 12 to 14 weeks (after the period of physiologic return of intestine to abdomen during embryonic development). Exception to this is herniated liver detected outside the abdominal wall; this finding is never normal

Omphalocele (exomphalos) is a congenital midline abdominal wall defect in which a variable amount of intestine and often other organs (eg, liver) are herniated outside the abdominal wall 

Herniated viscera is covered by a membrane—inner surface peritoneum, outer surface amnion, and Wharton jelly between the layers—unless the membrane ruptured in utero

Umbilical vessels insert directly into the membrane instead of the intact body wall

Often detected by routine prenatal ultrasonography and/or elevated α-fetoprotein levels 

Classification

• Based on size of defect
  • Minor 
    • Abdominal defect is small
    • Can generally be repaired with primary closure
  • Major (giant) 
    • Giant omphalocele is not consistently defined but generally is large, either in actual size (fascial defect or sac larger than 5 cm) or relative to size of fetus or neonate, and/or includes herniation of more than 75% of liver
    • Often not amenable to primary fascial closure 
    • Higher risk for postnatal complications (eg, pulmonary hypoplasia, delayed closure of defect) related directly to omphalocele
• Based on involvement of liver 
  • Non–liver-containing defect
    • Contains bowel only
    • Associated with chromosomal abnormalities (eg, trisomies 13, 18, and 21) in up to 60% of cases (more frequently than in liver-containing defects) 
  • Liver-containing defect
    • Hernia contains liver

History

• Known prenatal diagnosis is most common presentation

Physical examination

• General
  • Often associated with other abnormalities
    • Dysmorphic features may be prominent in neonates with chromosomal abnormalities or congenital syndromes
    • Patients with Beckwith-Wiedemann syndrome may rapidly develop seizures from profound hypoglycemia
    • Neonates may be large for gestational age, particularly when associated with Beckwith-Wiedemann syndrome 
  • May present with respiratory insufficiency at birth, secondary to
    • Pulmonary hypoplasia (associated with large or giant omphaloceles)
    • Prematurity
• Omphalocele
  • Midline abdominal mass at site of umbilical cord insertion
  • Often large (greater than 4 cm) 
  • Covered by membrane unless membrane ruptured in utero or during delivery
  • Umbilical vessels insert directly into membrane
  • Herniated small intestines are visible through membrane
  • Amount and type of herniated viscera depend on size and location of defect on abdominal wall
    • Umbilical location of defect is most common
      • Other viscera contained in membranous sac may include the following:
        • Liver 
        • Spleen 
        • Gonad (ie, testicle, uterus, ovary, fallopian tube) 
        • Colon 
        • Stomach 
        • Bladder 
    • Supraumbilical (epigastric) location
      • Heart is often contained in the membranous sac
    • Infraumbilical location
      • Often, concomitant cloacal or bladder exstrophy occurs
  • Very large or giant omphalocele may be associated with narrow thorax and reduced thoracic cavity size or underdeveloped abdominal cavity 

Associated congenital anomalies

• Truly isolated omphalocele is fairly uncommon occurring in only approximately 14% of all omphaloceles in some series 
• 50% to 70% of neonates with omphalocele have significant associated anomalies 
  • Chromosomal anomalies are present in approximately 30% of patients with omphaloceles 
    • Most common are trisomy 13, 14, 15, 18, and 21 
    • Small omphaloceles without liver herniation are more commonly associated with chromosomal abnormalities 
  • Cardiac defects are present in 30% to 50% of patients with omphaloceles 
    • Pulmonic valve stenosis and tricuspid atresia
    • Coarctation of aorta 
    • Atrial septal defect and/or ventricular septal defect 
    • Tetralogy of Fallot 
  • Multiple anomalies
    • Are more frequent in neonates with smaller defects compared with larger or giant omphaloceles 
    • Are often clustered in a variety of syndromic patterns 
      • Beckwith-Wiedemann syndrome (OMIM #130650) is the most common 
        • Up to 10% of neonates born with omphalocele have Beckwith-Wiedemann syndrome 
        • Characterized by macroglossia, exophthalmos, large round facies, gigantism, hemihypertrophy, organomegaly, early hypoglycemia, and increased risk of embryonic tumors (eg, Wilms, hepatoblastoma, neuroblastoma, rhabdomyosarcoma)
        • Hypoglycemia is a result of excess insulin secretion caused by pancreatic hyperplasia
  • Other anomalies that occur with omphaloceles may include the following:
    • Central nervous system anomalies (in up to 33% of patients) 
      • Macrocephaly or microcephaly 
      • Spina bifida and meningomyelocele 
      • Dandy-Walker malformation 
      • Holoprosencephaly and anencephalus 
    • Pulmonary hypoplasia 
    • Cleft lip and palate 
    • Axial, cranial, and limb skeletal anomalies 
    • Renal anomalies 
    • Anogenital defects (eg, ambiguous genitalia, imperforate anus) 

Causes

• Underlying cause is postulated; specific underlying insult is often undetermined
  • Underlying cause appears to be primarily genetically determined 
  • In general, omphalocele represents failure of the midgut to return to the abdominal cavity following transient herniation during fetal development 
    • Physiologic herniation of intestine into the base of umbilical cord usually occurs about week 6 to 11 of development and returns to the abdominal cavity by week 10 to 12 
  • Thought to result from a failure of embryonic folds to meet in midline in early embryogenesis
  • Herniation of intestine and sometimes liver occurs
    • Herniation of other organs can also occur (eg, stomach, spleen, gonads)

Risk factors and/or associations

Age

• Neonates are affected
  • Incidence is approximately 2 per 10,000 live births 
  • Incidence has remained stable over the past few decades

Sex

• Slight male predominance 

Genetics

• Most cases are sporadic 
• Familial cases are rare 
  • Autosomal dominance inheritance pattern for duplication at 1p31 is reported (OMIM #164750) 
  • X-linked inheritance pattern is reported (OMIM #310980) 

Other risk factors/associations

• Young or advanced maternal age (younger than 20 years or older than 40 years) 
• Conception via assisted reproductive therapy 
• Risk increases in presence of fetal aneuploidy
  • Trisomy 13, 14, 15, 18, and 21 
• Risk increases in patients with many genetically predetermined congenital syndromes, notably 
  • Beckwith-Wiedemann syndrome
  • Donnai-Barrow syndrome 
  • Shprintzen-Goldberg syndrome 

Diagnostic Procedures

Primary diagnostic tools

• Prenatal diagnosis (most common)
  • Suspect diagnosis based on abnormal findings detected on routine prenatal ultrasonography and/or elevated α-fetoprotein level
    • Overall prenatal detection rate is about 83% 
    • Most defects are diagnosed by middle of second trimester
  • Confirm and characterize abdominal wall defect and associated anomalies with high resolution comprehensive fetal ultrasonography
    • Fetal MRI is also routinely performed to further characterize the defect and calculate lung volumes
  • Further prenatal diagnostic evaluation is recommended and typically includes the following:
    • Fetal echocardiography to screen for associated cardiac defects
    • Amniocentesis and/or chorionic villous sampling for genetic studies and possibly focused molecular assessment for Beckwith-Wiedemann syndrome 
    • Combination of prenatal ultrasonography and karyotyping may identify 60% to 70% of significant associated defects 
• Postnatal diagnosis
  • Postnatal physical examination establishes diagnosis and severity of abdominal wall defect
  • Perform detailed systemic clinical examination in all neonates to assess for presence of associated anomalies
    • Includes detailed cardiac examination and search for concomitant signs of dysmorphology that may be associated with a congenital syndrome
  • Obtain serial glucose levels
    • Hypoglycemia is common among premature neonates, small-for-gestational-age neonates, and neonates with Beckwith-Wiedemann syndrome
  • Perform secondary diagnostic evaluation to assess for additional associated anomalies
    • About one-third of fetuses without identifiable associated anomalies on prenatal studies have them detected in the postnatal period 
    • Postnatal diagnostic evaluation often includes the following:
      • Cardiology consultation for examination and echocardiography 
      • Abdominal ultrasonography to assess for associated renal anomalies 
      • Cranial ultrasonography to assess for central nervous system anomalies 
      • Genetic consultation, chromosome analysis, and genetic studies to evaluate for Beckwith-Wiedemann syndrome if not previously done in prenatal period 
  • Obtain other routine studies to guide neonatal resuscitation 
    • Often includes CBC, electrolyte levels, blood gas values, and chest radiograph

Laboratory

• Maternal serum α-fetoprotein
  • Often elevated in mothers carrying fetuses with omphalocele 
• Genetic studies
  • Perform karyotyping to assess for fetal aneuploidy on fetal cells obtained through chorionic villous sampling (11-13 weeks) or amniocentesis (more than 15 weeks) 
  • Comparative genomic hybridization (CGH microarray) molecular analysis is recommended when additional fetal structural anomalies are noted on ultrasonogram 
    • Microarray analysis can identify chromosomal aneuploidy, large changes in the structure of chromosomes, and submicroscopic abnormalities that are too small to be detected by traditional karyotype 
  • Beckwith-Wiedemann syndrome

Imaging

• Prenatal ultrasonography performed after the first trimester
  • Abnormal findings that suggest possibility of abdominal wall defect, prompting high resolution comprehensive fetal ultrasonography, include the following: 
    • Abnormalities in fetal growth
    • Abnormalities in amniotic fluid level
    • Defect in abdominal wall with visceral herniation
  • Test characteristics
    • Reported sensitivity is variable owing to the following:
      • Operator experience or inexperience 
      • Inability to see abdominal wall due to fetal position during screening, which is designed primarily to assess fetal number, position, and gestational age 
    • Highly specific (greater than 95%) for diagnosis when abdominal wall defect is seen 
• Fetal MRI
  • Confirms ultrasonographic findings and characterizes extent of liver and intestinal herniation
  • Assesses lung volume and evaluates for presence of other anatomic abnormalities

Differential Diagnosis

• Gastroschisis
• Umbilical cord hernia

Treatment Goals

• Consult with team of experts early to plan perinatal care and neonatal management strategy at tertiary care facility with resources to support neonate
• Effectively resuscitate and stabilize neonate while protecting bowel and any exposed viscera from further injury 
• Definitive surgical management involves reducing intestine and viscera to intraperitoneal location and closing fascia and skin while minimizing risk of further injury to vital organs 
• Focus on nutritional status of neonate with early total parenteral nutrition and careful advancement of enteral feedings when appropriate to facilitate safe discharge and minimize adverse outcomes

Admission criteria

Criteria for ICU admission

• Manage all patients in the neonatal ICU

Recommendations for specialist referral

• Consult a multidisciplinary team of specialists with experience managing fetuses/neonates that have abdominal wall defects; core team includes pediatric surgeon, high-risk obstetrician, and neonatologist 
• Consult a geneticist to provide diagnostic recommendations and genetic consultation for family 

Treatment Options

Prenatal and perinatal management

• It is paramount for a team of specialists (eg, pediatric surgeon, neonatologist, high risk obstetrician) to counsel the family regarding treatment and prognosis of patients with abdominal wall defects 
• Transfer prenatal care to obstetrician who handles high-risk pregnancies and who can monitor and deliver at a tertiary care center—with neonatal ICU—supported by a team experienced managing neonates with complex surgical issues 
• Goal for the mother is term vaginal delivery, unless fetal or maternal obstetric indications dictate need for cesarean section 
  • Cesarean section may be elected for the patient with large omphalocele, especially when it contains liver, in an effort to prevent rupture of membrane during labor or dystocia 
  • Mortality and short-term outcomes are not affected by mode of delivery 
• Individualized monitoring with serial fetal ultrasonography and stress testing is recommended
• Rates of pregnancy termination are high for many reasons, including concomitant major anomalies, aneuploidy, high rate of spontaneous fetal demise, and spontaneous abortion 

Neonatal resuscitation

• Concentrate initial management on stabilization of airway, breathing, and circulation (ABCs)
  • Manage according to neonatal resuscitation guidelines for intubation and mechanical ventilation 
    • Term neonates may require additional respiratory assistance because they have increased incidence of pulmonary hypoplasia and associated cardiac defects at birth 
    • Surfactant replacement may be required for preterm neonates (Related: Respiratory distress syndrome in neonates)
  • Obtain IV access for aggressive fluid replacement and management
    • Neonates are at high risk for excessive fluid loss from third spacing and evaporation from exposed viscera and increased surface area
    • Upper extremity or scalp veins are preferred for initial peripheral access 
    • Umbilical artery and vein may be cannulated 
      • Cannulation may be difficult owing to abnormal insertion and course of vessels 
  • Warm neonate under radiant heater or heated incubator 
    • Neonates are at high risk for hypothermia
• Protect viscera from mechanical trauma, minimize heat and evaporative loss, and prevent vascular compromise
  • Protect intact omphalocele membrane
    • Apply nonadherent moist dressing 
    • Small tear in membrane may be temporized with absorbable suture material 
      • Larger disruption in membrane is treated more urgently; goal is expedient repair of open abdominal evisceration 
  • Manage exposed viscera in neonates who have ruptured omphalocele 
    • Apply sterile, warm, saline-soaked gauze or sponge to extruded viscera 
    • Cover entire lower extremity in a large sterile plastic bag (ie, bowel bag) or wrap extruded viscera in sterile cling film
    • Position neonate on right side and stabilize bowel mass centrally, supporting the sides and bottom 
      • Positioning helps to avoid kinking of mesenteric vascular pedicle and prevent traction on vasculature of liver 
• Assess and treat hypoglycemia 
  • Neonates who are premature, with intrauterine growth restriction, and with Beckwith-Weidemann are at increased risk for hypoglycemia
• Maintain adequate intravascular volume
  • Neonates with exposed bowel (eg, ruptured omphalocele) often require at least 2 to 3 times the maintenance fluids that a healthy newborn needs 
  • Neonates with intact omphalocele have lower fluid loss than neonates with open evisceration, but they generally have higher fluid requirements than neonates with intact abdominal wall 
• Gastric decompression 
  • Prevent distention and minimize risk of aspiration by suctioning with nasogastric or orogastric tube or by using gravity drainage
• Antibiotic prophylaxis 
  • Begin antibiotics for neonates with ruptured omphalocele 
  • Most experts recommend broad spectrum antibiotics, when indicated, in consultation with pediatric surgeon and members of the neonatology team 

Surgical management

• Timing and specific definitive treatment is individualized according to size and type of defect, size and stability of neonate, and presence and type of associated anomalies 
  • Initial management priority is to identify and treat any associated life-threatening anomalies and/or respiratory compromise caused by pulmonary hypoplasia
  • Can be difficult to determine appropriate timing for definitive closure of defect
  • Primary difference in managing ruptured omphalocele compared with one with intact membrane is that there is less urgency to perform definitive operative closure when omphalocele membrane is intact 
• Several definitive techniques are available for treatment and include the following:
  • Nonoperative delayed closure using escharotic therapy 
    • Common approach because it avoids early anesthesia and allows any abdominovisceral disproportion or respiratory issues to resolve
    • Considered appropriate treatment for poor surgical candidates, when primary closure is unlikely to be easy because the defect is large, and when there is abdominoviscera disproportion
    • May be preferred approach for giant omphalocele compared with staged surgical closure owing to lower associated mortality rates and shorter time to full enteral feeding tolerance 
    • Involves treating membrane with a topical agent (eg, silver sulfadiazine, silver-impregnated dressing, povidone-iodine, neomycin, bacitracin) and occlusive dressing to allow membrane to granulate, epithelialize, and contract over weeks to months 
      • Complete neoepithelialization of the sac may take up to 3 months 
      • Can apply elastic bandages to gently compress and further reduce viscera into intraperitoneal location after epithelization is complete
      • Elective ventral hernia repair is then performed around age 6 to 12 months 
    • Enteral feedings can begin during this process, and wound care can be managed at home once patient is stable for discharge
  • Staged surgical closure (delayed primary closure)
    • Appropriate for relatively larger omphalocele in neonate who is stable enough for a planned surgical closure
    • Many strategies for staged surgical closure and management of large defects are available, including the following:
      • Skin flap mobilization and coverage
      • Component separation technique, which involves translation of abdominal muscle layers to enlarge abdominal wall 
      • Fascial patching with synthetic or biologic bridging mesh; resultant hernia is repaired eventually 
      • Vacuum-assisted closure 
      • Use of intra-abdominal tissue expanders 
    • May involve use of a polymeric silicone silo in cases of omphalocele rupture
  • Early primary closure with definitive repair 
    • Less common approach
    • May be appropriate for neonates with relatively small defects who are otherwise good candidates for surgery
    • Involves excision of membrane, reduction of herniated viscera, and closure of fascia and skin
    • Of note, membrane adherent to underlying liver is often left intact to avoid injury to liver capsule

Drug therapy

• Dextrose (for documented hypoglycemia) (Related: Beckwith-Wiedemann syndrome)
  • Dextrose 10% Solution for Injection; Neonates, Infants and Children: 2 to 3 mL/kg bolus; followed with continuous infusion rate beginning at 4 to 8 mg/kg/minute. 
  • Reassess serum glucose after bolus and every 30 to 60 minutes until stable. 
  • Titrate glucose infusion rate to maintain normoglycemia with glucose greater than 40 to 60 mg/dL. 
  • Dextrose concentrations up to 25% (D25) may be required to deliver higher glucose infusion rates (15-30 mg/kg/min); central line is required for glucose infusion concentrations greater than 12.5%. 
  • Consider glucagon infusion for persistently low serum glucose concentrations despite glucose infusion rate of greater than 20 mg/kg/min, particularly in neonates with hyperinsulinism related to Beckwith-Wiedemann syndrome. 
• Antibiotics (for ruptured omphalocele)
  • Ampicillin
    • Ampicillin Sodium Solution for injection; Neonates 0 to 7 days weighing 2 kg or less: 50 mg/kg/dose IV/IM every 12 hours recommended by AAP; 100 mg/kg/dose IV/IM every 12 hours also acceptable for presumed early-onset GBS sepsis. FDA-approved dosage is 50 mg/kg/dose IV/IM every 12 hours for neonates 34 weeks gestation or less and 50 mg/kg/dose IV/IM every 8 hours for neonates more than 34 weeks gestation.
    • Ampicillin Sodium Solution for injection; Neonates 0 to 7 days weighing more than 2 kg: 50 mg/kg/dose IV/IM every 8 hours recommended by AAP; 100 mg/kg/dose IV/IM every 12 hours also acceptable for presumed early-onset GBS sepsis. FDA-approved dosage is 50 mg/kg/dose IV/IM every 12 hours for neonates 34 weeks gestation or less and 50 mg/kg/dose IV/IM every 8 hours for neonates more than 34 weeks gestation.
    • Ampicillin Sodium Solution for injection; Neonates older than 7 days weighing 2 kg or less: 50 mg/kg/dose IV/IM every 8 hours recommended by AAP; FDA-approved dosage is 75 mg/kg/dose IV/IM every 12 hours for neonates 34 weeks gestation or less and 50 mg/kg/dose IV/IM every 8 hours for neonates more than 34 weeks gestation.
    • Ampicillin Sodium Solution for injection; Neonates older than 7 days weighing more than 2 kg: 50 mg/kg/dose IV/IM every 6 hours recommended by AAP; FDA-approved dosage is 75 mg/kg/dose IV/IM every 12 hours for neonates 34 weeks gestation or less and 50 mg/kg/dose IV/IM every 8 hours for neonates more than 34 weeks gestation.
    • Ampicillin Sodium Solution for injection; Infants, Children, and Adolescents: 200 to 400 mg/kg/day IV/IM divided every 6 hours (Max: 12 g/day) recommended by the AAP; FDA-approved dosage is 150 to 200 mg/kg/day IV/IM divided every 3 to 4 hours.
  • Gentamicin
    • Monitor renal function closely in all patients receiving gentamicin. Measure gentamicin serum concentrations if there is a decrease in urine output or a laboratory value that suggests a change in renal function
    • Therapeutic drug monitoring (measurement of gentamicin blood levels to guide therapy) is recommended if drug is given for more than 48 hours, owing to narrow therapeutic index. Although initial doses can be recommended, individualize maintenance dosing based on pathogen, infection site, and serum concentrations
    • Gentamicin Sulfate Solution for injection; Neonates 0 to 7 days weighing less than 1.2 kg: 2.5 mg/kg/dose IV/IM every 18 to 24 hours. FDA-approved dosage is 2.5 mg/kg/dose IV/IM every 12 hours.
    • Gentamicin Sulfate Solution for injection; Neonates 0 to 7 days weighing 1.2 to 2 kg: 2.5 mg/kg/dose IV/IM every 12 to 18 hours.
    • Gentamicin Sulfate Solution for injection; Neonates 0 to 7 days weighing more than 2 kg: 2.5 mg/kg/dose IV/IM every 12 hours; extend interval to 18 to 24 hours for neonates on ECMO. Individualize subsequent dosing based on serum concentrations. Dosage adjustment needed after decannulation.
    • Gentamicin Sulfate Solution for injection; Neonates 8 to 29 days weighing less than 1.2 kg: 2.5 mg/kg/dose IV/IM every 18 to 24 hours. FDA-approved dosage is 2.5 mg/kg/dose every 8 hours.
    • Gentamicin Sulfate Solution for injection; Neonates 8 to 29 days weighing 1.2 to 2 kg: 2.5 mg/kg/dose IV/IM every 8 to 12 hours.
    • Gentamicin Sulfate Solution for injection; Neonates 8 to 29 days weighing more than 2 kg: 2.5 mg/kg/dose IV/IM every 8 hours; extend interval to 18 to 24 hours for neonates on ECMO. Individualize subsequent dosing based on serum concentrations. Dosage adjustment needed after decannulation.

Nondrug and supportive care

• Nutrition
  • Begin enteral feedings early and advance slowly 
    • Maternal breast milk is preferred over formula to reduce risk of necrotizing enterocolitis 
  • Include early oral stimulation to diminish risk of losing sucking-swallowing reflex

Comorbidities

• Management of extra-abdominal gonad(s)
  • Both the ovaries and testicles may be eviscerated
  • Place into abdominal cavity at time of closure 
  • Testes generally descend with time; orchiopexy is performed for those that do not descend by age 6 months to 1 years (Related: Undescended testis)

Monitoring

• Prenatal monitoring
  • Primary reason to use prenatal monitoring is to assess for obstetric indications for delivery
  • Many fetal monitoring parameters have been assessed, and few correlate well with morbidity and mortality
    • Maximum omphalocele diameter to head circumference ratio 
      • Value of 0.21 or more has 84% sensitivity and 58% specificity for predicting challenging cases (defined as cases that need staged closure or in which respiratory insufficiency is present) 
  • Surveillance routine is not rigorously established and is often individualized; general prenatal monitoring may include the following:
    • Estimation of fetal weight can be difficult when fetus has abdominal wall defects because cannot accurately measure abdominal circumference
      • Specific formula is available to estimate fetal weight based on biparietal diameter, occipitofrontal diameter, and femur length 
    • Ultrasonogram every 2 weeks to evaluate fetal growth, amniotic fluid, and condition of herniated bowel loops, and to monitor any associated congenital anomalies 
    • Fetal nonstress test
      • Weekly for fetuses less than 32 weeks of gestation with abnormal fetal growth or amniotic fluid volume 
      • Twice weekly for all fetuses 32 weeks of gestation and beyond 
    • Frequency of monitoring is increased in pregnancies found to have additional complications (eg, abnormal amount of amnionic fluid, intrauterine growth restriction, associated congenital anomalies and/or syndrome)
      • Additional monitoring parameters are dictated by standard obstetric guidelines (eg, measurement of Doppler umbilical artery flow when fetal growth restriction is suspected)
• Monitoring in the immediate neonatal period
  • Vital signs, measures of perfusion, and urine output guide initial resuscitation
    • Monitor fluid status using serial assessment of perfusion and urine output 
    • Monitor routine vital signs with attention to heart rate and mean arterial pressure 
  • Monitor core body temperature and maintain normothermia
  • Monitor serial electrolytes, blood gases, and glucose with attention to development of hypoglycemia 
  • Obtain echocardiogram to screen for pulmonary hypertension at age 2 days or older; especially important in infants with liver-containing omphalocele or who require intubation at birth 
• Monitoring for complications after definitive closure of abdominal wall defect
  • Significant visceroabdominal disproportion (ie, large amount of herniated viscera compared to underdeveloped abdominal cavity) may result in increased intra-abdominal pressure leading to abdominal compartment syndrome
  • Carefully monitor for intra-abdominal compartment syndrome after reducing viscera and closing abdominal wall defect
  • Monitor serial abdominal examinations with attention to any signs of obstruction (eg, progressive distention, increase in nasogastric or orogastric output) or necrotizing enterocolitis (eg, abdominal wall discoloration, tenderness, rigidity) 
  • Rising intra-abdominal pressure is primarily reflected by untoward hemodynamic (eg, reduced cardiac output, reduced splanchnic perfusion pressure) and ventilatory effects
    • Measured intra-abdominal pressure of greater than 15 mm Hg is consistent with intra-abdominal hypertension 
    • Measured intra-abdominal pressure of greater than 20 mm Hg is consistent with abdominal compartment syndrome 
  • Various strategies exist to monitor for abdominal compartment syndrome and diminished perfusion to viscera
    • Monitor urine output and peripheral perfusion
      • Lower extremity edema and diminished capillary refill may herald significant caval compression
      • Oliguria and poor peripheral perfusion may be clinical indicators of inability to tolerate closure
        • Goal for urine output is at least 1 mL/kg/hour 
        • Diminished lower extremity perfusion is concerning for increased intra-abdominal pressure
    • Monitor for ineffective ventilation and rising central venous pressure
      • Precipitous need for increased ventilatory support pressures after bowel reduction predicts inability to tolerate closure
      • Increase in central venous pressure by more than 4 mm Hg is concerning for increased intraabdominal pressure
      • Worsening of ventilatory parameters (eg, rising end tidal CO₂, need for increased peak inspiratory pressures higher than 25 cm H₂O) may predict unsuccessful closure 
    • Consider indirect measurements of intra-abdominal pressure such as intragastric pressure or intravesicular pressure 
      • Pressures of greater than 20 mm Hg predict diminished perfusion to bowel and kidney if fascia is closed 
    • Consider monitoring for unexplained metabolic acidosis that may result from diminished splanchnic perfusion pressure and/or hepatic venous congestion
  • Findings concerning for increasing intra-abdominal pressure and abdominal compartment syndrome necessitate emergent take down of abdominal wall defect closure and placement of silo 
• Postoperative care
  • Involves general postoperative surgical care with attention to nutrition and monitoring for postoperative complications
• Patients with Beckwith-Wiedemann syndrome
  • Long-term monitoring for childhood tumors (eg, Wilms, hepatoblastoma) is required (Related: Beckwith-Wiedemann syndrome)

Complications

• Prenatal complications
  • Intrauterine growth restriction
    • Occurs to 5% to 35% of fetuses with omphalocele 
  • Premature delivery
    • May occur, but not as common as for neonates with gastroschisis 
  • Spontaneous abortion
    • Ends 5% to 10% pregnancies involving fetuses with omphalocele 
  • Fetal death
    • Usually caused by severe associated structural or genetic abnormalities
  • Intrauterine rupture of omphalocele membrane
    • Associated with a higher risk of pulmonary hypoplasia, sepsis, and intestinal fistula than unruptured omphalocele 
• Postnatal complications
  • Pulmonary hypoplasia and insufficiency
    • Unsuspected pulmonary hypoplasia may be evident at birth and requires immediate intubation and mechanical ventilation 
    • Larger sized omphalocele defects are associated with higher risk for pulmonary hypoplasia 
  • Pulmonary hypertension
    • May be caused by pulmonary hypoplasia or left to right shunting from congenital heart disease 
    • More common with giant omphaloceles and those containing liver
  • Ruptured omphalocele
  • Necrotizing enterocolitis
  • Sepsis
  • Recurrent lung infections and asthma 
  • Gastroesophageal reflux 
    • May be severe and recalcitrant
  • Intermittent abdominal pain 
    • Persisting into young adulthood is common
  • Feeding difficulty and failure to thrive 
    • May occur early in life
  • Adhesive bowel obstruction
  • Intestinal malrotation
    • Intestinal malrotation is common and places patient at risk for volvulus 
    • Overall risk for volvulus in patients with omphalocele is lower than in patients with congenital intestinal malrotation without abdominal wall defect
      • Postoperative adhesions are common after abdominal wall defect repair and are thought to protect from volvulus 
    • Although some experts perform a prophylactic Ladd procedure to secure intestines and prevent volvulus after abdominal wall defect closure, is not standard procedure
  • Cosmetic concerns about lack of umbilicus and abdominal scarring 
    • May require plastic surgery for umbilical reconstruction
• Surgical complications related to closure of abdominal wall defect
  • Postoperative
    • Abdominal compartment syndrome 
      • Defined as intra-abdominal pressure greater than 20 mm Hg or presence of symptoms or signs related to intra-abdominal hypertension (eg, decreased cardiac output, oliguria, respiratory acidosis, metabolic acidosis, rising hepatic transaminases)
      • Compromised perfusion to vital abdominal organs (eg, bowel, kidneys) and caval compression can lead to intestinal necrosis with necrotizing enterocolitis and/or sepsis, acute renal failure, wound dehiscence, or inability to ventilate 
    • Prolonged period of ventilation
      • Many neonates with omphalocele have some degree of pulmonary hypoplasia; pressure on diaphragm after surgical closure often further impairs ventilation necessitating prolonged mechanical ventilation in some 
    • Fistula formation (eg, enteroenteric, enterocutaneous)
    • Hernia
      • Ventral and/or inguinal hernia are more common after skin flap or nonoperative management strategies 
  • Operative
    • Iatrogenic injury to bowel 
    • Vascular compromise from kinking of the vasculature, particularly hepatic veins during omphalocele reduction 
    • Dislodging tightly adherent omphalocele membrane from liver capsule can result in significant hemorrhage 
    • Inadvertent bladder injury can occur during resection of inferior portion of omphalocele sac; membrane overlying the bladder is often very thin 
• Silo complications
  • Be careful to avoid excessive pressure on contents of silo to avoid dislodging it 
  • Spring-loaded (preformed) silo complications 
    • Fascial defect enlargement
    • Mesh requirement at time of abdominal closure

Prognosis

• Survival of live-born neonates
  • Overall outcome is largely dependent on type and severity of concomitant associated anomalies and/or presence of chromosomal abnormality
    • Overall mortality rate may range up to 20% or 30% 
    • In isolated omphalocele (without concomitant defects), survival rate may reach up to 96% 
    • Ruptured omphalocele has less favorable outcome than omphalocele with an intact membrane 
    • Mortality is higher for patients with concomitant pulmonary hypertension (up to 45%) 
    • Patients requiring extracorporeal membrane oxygenation salvage therapy have a dismal prognosis with mortality rate over 80% 
    • Prognosis is very poor for neonates with trisomy 13 or 18 
  • Outcome based on defect location
    • Superior to the umbilicus
      • Outcome is often poor; survival is less than 40% and falls to 5% to 10% in neonates with severe ectopia cordis 
    • Inferior to the umbilicus
      • Outcome is often fair 
    • At the level of the umbilicus
      • Outcome is often good, depending on associated anomalies and size of defect 
      • Very large omphaloceles and defects containing large portions of liver may require multiple procedures
• Survival of infants diagnosed prenatally
  • Survival to birth rates are reported to be between 20% to 50% owing to high rates of pregnancy termination, intrauterine fetal death, and spontaneous abortion 
• Patients with pulmonary hypoplasia
  • Normalization of most lung function is typical at long-term follow-up; exercise intolerance may persist 
• Patients with failure to thrive
  • May depend on presence or absence of an associated congenital syndrome
  • Resolution by childhood is typical with final height and weight similar to peers when not associated with a specific congenital syndrome

Screening

At-risk populations

• Most abdominal wall defects are sporadic; therefore, all pregnant women are at risk for affected neonate

Screening tests

• Maternal serum α-fetoprotein level
  • Blood test is routinely obtained between 15 and 20 weeks of gestation to screen for neural tube defects, chromosomal abnormalities, and other defects
  • Levels are often elevated in patients carrying fetus with omphalocele 
  • If levels are increased then high-resolution comprehensive fetal ultrasonography and possibly amniocentesis are indicated
• Standard fetal ultrasonography
  • Used for general screening to assess gestational age and detect fetal abnormalities
  • Indicated in the routine screening of pregnant women who have a higher risk of fetuses with neural tube and other congenital defects, along with maternal serum α-fetoprotein
  • If abnormalities are detected (eg, possible abdominal wall disruption with visceral herniation, abnormal fetal growth parameters, abnormal amniotic fluid levels) then high-resolution comprehensive fetal ultrasonography is indicated

Sources

Ledbetter DJ: Congenital abdominal wall defects and reconstruction in pediatric surgery: gastroschisis and omphalocele. Surg Clin North Am. 92(3):713-27, x, 2012 Reference