An omphalocele is a rare birth defect in which a baby’s abdominal organs, such as the intestines and liver, protrude from the belly and lie exposed outside the abdomen. This is caused by a defect early in pregnancy when the muscles of the abdominal cavity fail to develop properly.
- What Is Omphalocele?
An omphalocele is a rare birth defect in which a baby’s abdominal organs, such as the intestines and liver, protrude from the belly and lie exposed outside the abdomen. This is caused by a defect early in pregnancy when the muscles of the abdominal cavity fail to develop properly.
The exposed organs are covered in a thin sac which can rupture, resulting in organ damage or infection. If your baby is diagnosed with omphalocele, their abdominal cavity and lungs may be smaller than normal and there is an increased risk of stillbirth.
Not much is known about what causes omphalocele, but it has been associated with advanced maternal age. Studies also show that women who are obese or overweight prior to pregnancy are more likely to have a baby with omphalocele, as are women who smoke, drink alcohol or take certain kinds of antidepressants during pregnancy.
Understandably, receiving the news that your baby has an omphalocele may bring fear and many questions. The staff at Fetal Care Center Dallas provides comprehensive counseling and guidance for parents with a fetus diagnosed with this anomaly. Our physicians are experienced in the diagnoses and treatment of this rare and complex condition.
Our team will closely monitor you and your baby for signs of preterm labor and intrauterine growth restriction, both of which are frequently associated with omphalocele. Once you deliver, we perform advanced surgical techniques with the goal of enabling your baby to live a full and healthy life.
- Prenatal Diagnosis of Omphalocele
The diagnosis of omphalocele is usually made by ultrasound in the middle or second trimester of pregnancy, around 20 weeks. The condition can also trigger abnormal results on prenatal blood screening tests. If not discovered during pregnancy, it becomes apparent at birth.
An amniocentesis may be recommended following diagnosis to evaluate your baby for chromosomal abnormalities or genetic syndromes.
Your pregnancy will be closely monitored, particularly in the third trimester. Regularly scheduled ultrasounds help us detect any developing issues that may arise during the rest of your pregnancy.
If fetal distress is detected, our team is prepared to respond quickly to promote the best outcome for both you and your baby.
In addition to maternal fetal medicine specialists, our team approach to treatment of omphalocele includes providing you with access to specialists in pediatric surgery, genetics, neonatology and pediatric cardiology.
Together, we will determine the best treatment option for your child based on the size of the defect, associated abnormalities and gestational age at delivery.
- How We Treat Omphalocele
Current treatments depend on the number of organs involved and how much of those organs remain outside of the belly at birth.
- If only parts of your baby’s intestines are protruding, the pediatric surgeon will return them to the abdomen soon after birth and close the opening in the abdominal wall. All of this will be done in one surgical procedure.
- If the omphalocele is large with multiple organs exposed, or there are associated respiratory problems, a phased treatment approach may be taken to allow for the gradual return of the abdominal contents to the belly. This staged approach provides time for the abdominal wall to stretch to accommodate the organs, and ensures that the lungs can continue to grow and expand without immediate pressure of surgical closure.
- In the most severe cases, physicians will take time to allow the body to grow skin over the membrane. Ace wraps may then be used to promote the development of space to accommodate the organs. Repair of the defect is likely to occur at 1-2 years of age.
No matter the treatment approach, you and any other caretakers will receive the information you need to be ready to transition to home with your child. Our physicians and staff are here to support you throughout that learning process.
- Long-Term Outcome for Babies with Omphalocele
Modern surgical advances have made life not only possible but also probable for babies born with omphalocele. The survival rate for babies with no additional abnormalities nears 90%.
For Healthcare Providers
- Omphalocele: Introduction
Omphalocele is a defect in the ventral abdominal wall that is characterized by an absence of abdominal muscles, fascia, and skin. The defect is covered by a membrane that consists of peritoneum and amnion. It can vary in size from a few centimeters to most of the ventral abdominal wall. Unlike gastroschisis, in omphalocele, the umbilical cord inserts into this membrane at a location distant from the abdominal wall (deVries, 1980). The defect is thought to be caused by an abnormality that occurs during the process of body infolding at 3 to 4 weeks of gestation (Dimmick and Kalousek, 1992). At that time, 3 folds occur simultaneously, and each is associated with a distinct type of omphalocele. Cephalic folding defects result in a high or epigastric omphalocele. An example of this is pentalogy of Cantrell, which consists of an epigastric omphalocele, anterior diaphragmatic defect, sternal cleft, pericardial defect, and associated intracardiac defects (Figure 1A) (Cantrell et al., 1958). A defect in lateral folding results in the classic omphalocele (Figure 1B) with a midabdominal defect. A defect in caudal folding results in a low or hypogastric omphalocele, as seen in bladder or cloacal exstrophy (Duhamel, 1963; Meller et al., 1989; Vasudevan et al., 2006). The spectrum of severity of abdominal wall abnormalities can vary from a small umbilical hernia to a large defect with extrusion of the abdominal viscera.
- Incidence of Omphalocele
The incidence of omphalocele ranges from approximately 1 in 4000 to 1 in 7000 livebirths (Baird and MacDonald, 1981; Lindham, 1981; Rankin et al., 1999; Stoll et al., 2001). The incidence of omphalocele is higher in combined livebirths and stillbirths (1 in 300 to 1 in 4000), reflecting the increased risk of intrauterine fetal death in cases of omphalocele. In fact, the overall incidence of abdominal wall defects is 20 times greater in stillborn than in liveborn infants (McKeown et al., 1953; Baird and MacDonald, 1981; Lindham, 1981; Carpenter et al., 1984). While the increase in the incidence of omphalocele has not been as great as for gastroschisis, there has been an 11% increase in prevalence of omphalocele (St Louis et al 2017). This rise in mothers with omphalocele is associated with extremes of maternal age with the rate among <20 and >40 years old double that of the general obstetric population (Byron-Scott et al 1998, Marshall et al 2015).
- Sonographic Findings
The diagnosis of omphalocele was made as early as 10 to 12 weeks of gestation by vaginal sonography, when an echogenic mass nearly equal to the size of the diameter of the fetal abdomen was found anterior to the fetal abdomen (Brown et al., 1989). The use of three-dimensional transvaginal ultrasound examination may facilitate this diagnosis early in gestation (Anandakumar et al., 2002; Tonni and Centini, 2006). The ultrasonographic appearance of omphalocele varies depending on the size and location of the defect, the presence of ascites, and the organs contained within the defect. However, a principal diagnostic feature of omphalocele is the umbilical cord insertion into the membrane covering the abdominal wall defect (Figure 2). This contrasts with gastroschisis, in which the defect is immediately to the right of the normal umbilical cord insertion into the abdominal wall. The cord insertion site at the caudal apical portion of the omphalocele membrane can be visualized with color flow Doppler studies on sagittal or oblique images. An additional diagnostic feature is the presence of the intraabdominal portion of the umbilical vein coursing through the central portion of the defect. Omphaloceles are characterized in utero by the presence of a membrane; however, occasionally this membrane will rupture. In cases of ruptured omphalocele, the abdominal contents are floating free in the amniotic cavity, similar to gastroschisis. However, unlike gastroschisis, in ruptured omphaloceles, the defects are usually large and have at least exposed, if not extracorporeal, liver (Figure 3).
- Differential Diagnosis
It is usually easy to distinguish sonographically between gastroschisis, with its cord insertion on the abdominal wall, and omphalocele, with the cord insertion at the apex of the membrane encompassing the abdominal wall defect. It sometimes is more difficult to distinguish between a small omphalocele and a hernia of the cord or between a ruptured omphalocele, gastroschisis, and body-stalk anomaly.
Two syndromes deserve mention in the context of omphalocele: pentalogy of Cantrell and Beckwith–Wiedemann syndrome. Pentalogy of Cantrell is characterized by the presence of an epigastric omphalocele and defects of the sternum, anterior diaphragm, and diaphragmatic pericardium, with associated intracardiac lesions (Cantrell et al., 1958; Toyama, 1972; Spitz et al., 1975). Cantrell et al. (1958) hypothesized that the syndrome might have resulted from a developmental failure of a segment of lateral mesoderm around 14 to 18 days of embryonic life. Consequently, there is a lack of development of the transverse septum of the diaphragm and a lack of migration of the two paired mesodermal folds of the upper abdomen. A defect in the lower sternal region develops, allowing for protrusion of the heart and the upper abdominal organs. The syndrome is very rare. Fewer than 90 cases have been described (Craigo et al., 1992). Ghidini et al. (1988) reviewed the Yale experience and found 10 cases of pentalogy of Cantrell. Five pregnant patients elected termination and the remaining five delivered infants; there were no survivors beyond 3 months of age. A number of other anomalies can be associated with pentalogy of Cantrell, including craniofacial abnormalities, chromosomal abnormalities, clubfeet, malrotation of the colon, hydrocephalus, and anencephaly (Craigo et al., 1992). The defects themselves can vary in severity, ranging from only rectus muscle diastasis to a large omphalocele. The most common cardiac abnormalities include atrial and ventricular septal defects, and tetralogy of Fallot (Bryker and Breg, 1990). The prognosis in pentalogy of Cantrell is directly related to the severity of the cardiac defect.
The Beckwith–Wiedemann syndrome, otherwise known as exomphalos-macroglossia-gigantism (EMG) syndrome, consists of the presence of omphalocele, visceromegaly, macroglossia, and severe neonatal hypoglycemia. Cardiac abnormalities are also frequently seen in this syndrome. Greenwood et al. (1977) found that 12 of 13 patients with this syndrome had cardiovascular malformations, and 7 of the 12 had structural abnormalities. Malignant tumors can develop in 10% of patients, including Wilms’ tumor, hepatoblastoma, and adrenal tumors (Sotelo, 1977). This syndrome does not have any obligatory anomalies, and the diagnosis has been made without macroglossia or omphalocele (Cohen and Ulstrom, 1979). Evidence of macroglossia, or enlargement of adrenal glands, liver, kidneys, or pancreas, in the setting of omphalocele should alert one to the possible diagnosis of Beckwith–Wiedemann. These findings are rare and seldom seen prior to the third trimester.
In a large series of 1500 newborns with omphalocele, Beckwith-Wiedemann syndrome was the most common genetic syndrome accounting for 6% of cases followed by 3% for trisomy 13, 2% for trisomy 18 and 1% for trisomy 21 (Corey et al 2014). The prevelance of Beckwith-Wiedemann syndrome may be as high as 10-20% in fetuses with isolated omphalocele.
- Antenatal Natural History
Omphalocele can present as part of a syndrome or as an isolated defect. A list of the syndromes associated with omphalocele is given in Table 1 (Stoll et al., 2008). The most important prognostic variable is the presence of associated malformations or chromosomal abnormalities. Visceral malformations can accompany omphalocele in 50% to 70% of cases, and chromosomal abnormalities can be seen in 30% to 69% (Paidas et al., 1994; Brantberg et al., 2005; Lakasing et al., 2006). Interestingly, the absence of the liver in the omphalocele has been correlated with fetal karyotypic abnormalities and perinatal mortality.
Nyberg et al. (1989) were the first to report an association between omphalocele contents and fetal chromosomal abnormalities. Other investigators have validated the finding that small defects in omphalocele that contain only bowel are associated with an increased risk of chromosomal abnormalities (Benacerraf et al., 1990; Getachew et al., 1991). In one study, chromosomal abnormalities were present in all 8 fetuses with intracorporeal liver, as opposed to 2 of the 18 fetuses with an extracorporeal liver. They also found a significant association between advanced maternal age (33 years and older) and abnormal karyotype. Gilbert and Nicolaides (1987) found that in a series of 35 fetuses, there was a high rate of chromosomal abnormalities (54%) with a predominance of trisomy 18 (17 of 19 cases of chromosomal abnormalities). Brantberg et al. (2005) found a higher incidence of karyotypic abnormalities when the omphalocele was central (69%) as opposed to epigastric (12.5%) in location.
The constellation of other associated malformations varies greatly, ranging from single, minor, nonlethal abnormalities to multiple complex life-threatening abnormalities that influence long-term prognosis more than the omphalocele itself. The pediatric literature (as opposed to the obstetric literature) has reported a better prognosis for neonates with omphalocele, due to the fact that many of the fetuses with multiple associated anomalies die in utero or during the immediate perinatal period. The report from Rijhwani et al. (2005) from King’s College Hospital is illustrative of this point, with survival of 34 of 35 neonates undergoing primary or staged closure. The same institution reported that fewer than 10% of the 445 prenatally diagnosed cases of omphalocele survived to repair (Lakasing et al., 2006).
Several investigators have described the impact of associated anomalies on survival in cases of omphalocele. Hughes et al. (1989) reviewed a series of 46 cases detected by prenatal ultrasound examination from three high-risk obstetric referral centers. In 43 of 46 cases, adequate follow-up information was available. Twenty-nine of the 43 cases (67%) had additional malformations, with 23 (79%) considered major and 6 (21%) considered minor. Three of the 29 pregnancies were terminated. There was a total of 58 individual anomalies in the 26 fetuses in which the pregnancy was continued. Cardiac anomalies were the most common (14 cases), in-cluding ectopia cordis (4). The other systems involved were skeletal (9), gastrointestinal (6), genitourinary (6), and central nervous (7). Fetal mortality was most strongly associated with the presence of concurrent malformations. Twelve of the 15 fetuses (80%) with concurrent malformations died, and the 3 that survived had isolated minor abnormalities. This was in contrast to 7 fetuses without additional anomalies that survived. In the Hughes et al. (1989) series, the size of the omphalocele was not associated with fetal mortality. Six of the 10 survivors had a transverse omphalocele to abdomen ratio of >0.6 and two omphaloceles measured more than 10 cm. Abnormal amniotic fluid volume was present in 9 of the 12 fetuses that died spontaneously, and 3 of these had no abnormalities detected on sonographic examination.
Tucci and Bard (1990) reviewed a 5-year Canadian experience consisting of 28 cases of omphalocele. They initially divided their cases into two groups on the basis of the size of the defect, small (<5 cm) and giant (>5 cm). Of the 12 fetuses with small omphaloceles only 1 died, whereas 10 of the 16 infants with giant omphalocele died and all except 1 had severe associated anomalies. There were five cases of congenital heart disease, three diaphragmatic hernias, and two central nervous system malformations. Of note, none of the six surviving infants had associated severe malformations. In this series, four of the survivors had liver herniation, which suggests that giant omphaloceles can have a favorable prognosis if other severe anomalies are not present.
Nicolaides et al. (1992) compiled their 8-year experience with omphalocele and reviewed both the obstetric and pediatric literature regarding the presence of chromosomal abnormalities and associated malformations. Of the 116 cases of omphaloceles, 87 (75%) had associated malformations. They also found a higher incidence of chromosomal abnormalities when the omphalocele contained only bowel as compared with omphaloceles that contained liver and bowel (25 of 44 vs. 17 of 72). In their summary, of 349 cases detected antenatally, 229 (65.6%) had associated malformations. Summarizing 13 studies with postnatal follow-up, an overall incidence of associated anomalies is 50%. They also noted an association with neural tube defects in chromosomally normal fetuses (Ardinger et al., 1987).
Pentalogy of Cantrell
Otopalata-digital type I syndrome
Nicolaides’ group reported their 11-year experience with 445 cases of omphalocele from the Harris Birthright Centre for Fetal Research at King’s College Hospital (Lakasing et al., 2006). In 250 cases (56%) the karyotype was found to be abnormal, and in 130 cases (30%) the karyotype was normal, with the remainder declining karyotype analysis. In the group with karyotype abnormalities, 248 (99%) underwent termination of pregnancy or died in utero. Among the 130 cases with normal karyotype, 74 (56%) were found to have associated structural anomalies.
Lakasing et al. (2006) reported that during an 11-year period from 1991 to 2001, 445 cases of omphalocele experienced less than 10% survival from operative repair due to termination of pregnancy, intrauterine fetal demise, and neonatal death.
- Management of Pregnancy
Elevated maternal serum α-fetoprotein (MSAFP) levels have traditionally been associated with open neural tube defects, but they are also associated with ventral abdominal wall defects (Brooke et al., 1979; Stiller et al., 1990; Killam et al., 1991). The sensitivity of MSAFP screening for the detection of abdominal wall defects will vary depending on whether it is omphalocele or gastroschisis and on the cutoff value of MSAFP used (Paidas et al., 1994). MSAFP screening has a much higher sensitivity for detecting gastroschisis than for detecting omphalocele. Palomaki et al. (1988) found that at each cutoff value of MSAFP, detection rates were higher for gastroschisis than for omphalocele. For example, at a cutoff value of >2.5 multiples of the median (MoM) and >3.0 MoM, the detection rates were more than 98% and 71%, and 96% and 65% for gastroschisis and omphalocele, respectively. The median MSAFP values for cases of omphalocele in this study were 4.1 MoM (Palomaki et al., 1988). The poorer detection rate for omphalocele is thought to be due to the presence of the intact amnioperitoneal membrane covering the abdominal cavities in unruptured omphalocele, as opposed to direct exposure of bowel to the amniotic fluid in gastroschisis (Paidas et al., 1994).
Once identified, a sonographic estimation of the size of the omphalocele, contents of the omphalocele sac, location of the umbilical cord insertion relative to the herniation, and the presence of an amnioperitoneal membrane should be documented. A careful sonographic search for other fetal anomalies should also be performed, including fetal echocardiography. Because of the high incidence of associated congenital cardiac disease (19%–32%), we recommend fetal echocardiography when an omphalocele is diagnosed (Greenwood et al., 1974; Carpenter et al., 1984; Crawford et al., 1985; Copel et al., 1986). The incidence of congenital heart disease is related to the embryology of the body fold defect. Ten percent of neonates with lateral fold defects have congenital heart disease, whereas the incidence approaches 100% if the cephalic fold is affected. Alternatively, if the caudal fold is involved, the incidence of associated congenital heart disease is low (Greenwood et al., 1974; Carpenter et al., 1984; Crawford et al., 1985; Copel et al., 1986).
Chromosomal analysis is strongly recommended due to the multiple studies that have documented a high rate of karyotype abnormalities. There are also other factors which may affect the prognosis in omphalocele including the presence or absence of pulmonary hypoplasia and the relative size of the omphalocele. Fetal MRI is particularly helpful in assessing pulmonary hypoplasia which may affect up to 37% of fetuses with giant omphalocele (Partridge et al 2012). The size of the omphalocele in relation to the size of the fetal abdomen is prognostically important as well. A ratio of the omphalocele diameter to the abdominal circumference <0.26 between 23 and 32 weeks’ is associated with a favorable prognosis wit better chances of a primary closure and avoiding immediate intubation and prolonged hospitalization (Fawley et al2016). In general, neonates with an extracorporeal liver, as is typical in giant omphaloceles, has a poorer prognosis (Nicholas 2009, Tassin 2013)
We have found that a team approach provides comprehensive counseling and advice for parents with a fetus diagnosed with this anomaly. In addition to maternal and fetal medicine specialists, the parents should meet with specialists in pediatric surgery, genetics, neonatology, and pediatric cardiology. This type of approach, coordinated by the maternal and fetal medicine specialists, affords the parents the opportunity to ask questions regarding postnatal surgery, postoperative care, and long-term outcome. If chromosomal abnormalities, associated anomalies, or a particular syndrome is suspected, these issues can be further discussed in detail. After a decision has been reached regarding continuation of the pregnancy, attention is then focused on antepartum surveillance for the development of preterm labor and intrauterine growth restriction. Both of these complications are frequently associated with omphalocele. Rates for preterm delivery range from 26% to 65% and for intrauterine growth restriction from 6% to 35% (Carpenter et al., 1984; Sermer et al., 1987; Lafferty et al., 1989; Sipes et al., 1990 a,b). There is also a high rate of emergency cesarean delivery due to fetal distress (Moretti et al., 1990; Molenaar and Tibboel, 1993). Because of the high incidence of intrauterine growth restriction, we perform serial ultrasound examinations to assess fetal growth and amniotic fluid volume. In addition, during ultrasound assessment we observe for occasional rupture of the omphalocele membrane, which exposes the herniated intestines to amniotic fluid.
In up to 50% of cases, significant pulmonary hypoplasia and pulmonary hypertension may complicate the neonatal course, particularly in giant omphaloceles (Tsakayannis et al., 1996; Lee et al., 2006). We routinely recommend MRI for total lung volume assessment at 32 to 34 weeks’ gestation to help identify fetuses at risk for these complications that, if present, become the overriding determinant of management in omphalocele.
The site and mode of delivery have been debated in the obstetric literature (Lewis et al., 1990; Lurie et al., 1999; Segel et al., 2001). The goal of the management of fetuses with omphalocele is to deliver the fetus as close to term as possible. Delivery at a tertiary care center provides optimal immediate care for the newborn (Hsieh et al., 1989; Lafferty et al., 1989; Lewis et al., 1990; Geijn et al., 1991). In addition, transporting the pregnant woman before delivery, rather than transporting the neonate after delivery, provides immediate neonatal surgical care and eliminates the risk of transporting a critically ill newborn.
Mode of delivery—vaginally or by cesarean—has been the subject of several retrospective reviews. No results from available prospective randomized trials have settled this issue. Older literature advocated the use of cesarean section (Cameron et al., 1978). However, the most recent retrospective reviews do not support the idea that cesarean delivery is associated with an improved survival rate (Sermer et al., 1987; Moretti et al., 1990; Sipes et al., 1990a; Kirk and Wah, 1983; Lurie et al., 1999; Segel et al., 2001). None of the six reported series show any benefit to cesarean delivery. The out-come of giant omphaloceles was not specifically addressed in these studies. Several other authors do not support routine cesarean delivery for fetuses with omphalocele (Carpenter et al., 1984; Hasan and Hermansen, 1986; Hsieh et al., 1989; Lafferty et al., 1989; Lewis et al., 1990; How et al., 2000). Labor it-self does not seem to adversely affect outcome, based on the study by Lewis et al. (1990), who compared outcome data from infants delivered via elective cesarean section with those whose delivery was preceded by labor. In cases of small omphaloceles, we currently recommend vaginal delivery and reserve cesarean delivery for routine obstetric indications. However, in isolated cases of giant omphalocele with a defect in the fetal abdomen measuring 5 cm or greater and extracorporeal liver by ultrasound examination, cesarean delivery may be necessary to avoid dystocia. Particularly in cases of extracorporeal liver, we recommend delivering by cesarean section. This approach under-scores the need for re-evaluation of the defect as pregnancy progresses.
- Fetal Intervention
There are no fetal interventions for omphalocele.
- Treatment of the Newborn
Delivery should occur in a tertiary care center, with neonatologists available for immediate resuscitation. Initial treatment consists of airway stabilization and sterile wrapping of the abdominal defect to preserve heat and minimize insensible fluid loss. A complete physical examination should be performed to rule out a syndromic diagnosis. Peripheral vascular access should be established and intravenous fluids given. Mechanical ventilation is frequently necessary, especially postoperatively, when abdominal contents replaced into a small abdominal cavity impede diaphragmatic excursion and lung expansion. Antibiotics are generally given during initial treatment of the newborn directed toward preoperative stabilization. Significant pulmonary hypoplasia and associated pulmonary hypertension may complicate the neonatal management of omphalocele from the delivery room on. This may be the most challenging management feature of up 37 to 50% of neonates with giant omphaloceles (Tsakayannis et al., 1996; Lee et al., 2006). In addition to pulmonary hypoplasia, it is not uncommon to see diffuse tracheobronchial malacia which may exacerbate the pulmonary hypertension associated with pulmonary hypoplasia. Positive end-expiratory pressure (PEEP) of 8-12 cm H2O or even higher may be necessary to stabilize the airway in cases in which tracheobronchial malacia is severe.
- Surgical Treatment
The surgical approach to the treatment of omphalocele has changed considerably over the past four decades. Until 1965, the only approach for the treatment of omphalocele was the skin flap technique described by Gross (1948). The principal disadvantage of this technique was the creation of a large disfiguring ventral hernia that ultimately required reoperation. This is usually not an insurmountable problem, and success has been reported for repair of these hernias. Considerable time (usually 6 months to 2 years, but sometimes longer) can lapse between initial surgery and final correction of the hernia (Swartz et al., 1985). If at all possible, primary fascial closure is the preferred method of repair because of a lower incidence of sepsis, biliary obstruction, and fistula and a reduced number of operations and rate of mortality in patients who undergo this repair (Figure 4) (Robin and Ein, 1976; Aaronson and Eckstein, 1977; Canty and Collins, 1983; Mabogunje and Mahour, 1984; Sauter et al., 1991).
For very large omphaloceles, a staged reduction using a prosthetic silo is preferred (Schuster, 1967; Allen and Wrenn, 1969; Othersen and Smith, 1986). This procedure consists of suturing a Silastic mesh to the rim of fascial defect, which then covers the herniated contents of the omphalocele (Figure 5). This technique consists of paralysis with neuromuscular blocking agents, enlargement of the fascial defect, and gradual stretching of the abdominal wall. Despite the success of the silon chimney (Allen and Wrenn, 1969), there remains a significant subset of patients in whom complete reduction is not achieved before complications of wound/fascial dehiscence, infection, enterocotomy, fistula, and systemic sepsis develop (Stringel and Filler, 1979; Towne et al., 1980; Hershenson et al., 1985; Hatch and Baxter, 1987; Adam et al., 1991; Lee et al., 2006). In this setting, attaining skin coverage with the use of biomaterials such as Alloderm may be the best option to reduce the great metabolic demands a large abdominal wall defect creates. Nonoperative (conservative) approaches to the treatment of omphalocele, the so called “paint and wait” approach, has grown in popularity with greater success rates in cases of severe visceroabdominal disproportion and much lower mortality rates, but they have the disadvantages noted above, as well as prolonged hospitalization (Mabogunje and Mahour, 1984; Hatch and Baxter, 1987; Nuchtern et al., 1995; Tsakayannis et al., 1996). The “paint and wait” approach allows the baby to gradually re-epithelialize the omphalocele membrane and avoids the stress of primary repair in a baby with significant repriatory compromise. Nutritional support can be challenging as it is difficult to provide enough calories by enteral feedings alone and supplemental TPN is usually necessary to allow the baby to grow and heal the defect. Once re-epithelialization has been achieved and the respiratory status is stable, wrapping the newborn with elastic bandage wraps will gradually reduce the size of the omphalocele and enlarge the peritoneal cavity. A delayed primary repair can be performed after a period of days to weeks. We have found this approach particularly useful in premature infants with giant omphaloceles, and in cases in which there is significant pulmonary hypoplasia or diffuse tracheobronchial malacia with concomitantly difficult ventilatory management. In cases with pulmonary hypoplasia or tracheobronchial malacia, this approach is particularly appealing, as improvement in the respiratory status may take 1 to 2 years.
Although the presence of multiple associated anomalies accounts for the majority of deaths in cases of omphalocele, respiratory complications also account for a significant percentage of the morbidity and mortality due to this lesion (Paidas et al., 1994; Tsakayannis et al., 1996; Lee et al., 2006). Newborns with omphalocele, particularly giant omphalocele, have a high incidence of respiratory insufficiency and chest-wall deformity. Some evidence suggests that impaired lung growth and pulmonary hypoplasia may even be evident on prenatal MRI lung volumes (Hershenson et al., 1985; Argyle, 1989; Thompson et al., 1993, Danzer et al2012).
Neonates may require prolonged mechanical ventilation because of the need for positive pressure to expand a chest compressed by a large abdominal mass. Bronchopulmonary dysplasia and chronic lung disease are potential long-term complications. Tracheostomy may be necessary, either due to pulmonary hypoplasia complicated by the development of bronchopulmonary dysplasia, or for tracheobronchial malacia. It is not uncommon for severe tracheobronchial malacia to be associated with giant omphaloceles and requires positive end-expiratory pressures (PEEP) of 10 or even 15 cm of H2O to keep the airway open. There should be a low thresh-old for bronchoscopic assessment of the airway to exclude this complication in cases of giant omphaloceles.
- Long-term Outcome
Even with primary repair of omphalocele, a protracted stay in the newborn nursery should be anticipated. Under the best circumstances, except for hernias of the umbilical cord, some period of mechanical ventilation following omphalocele repair may be required. In some cases of giant omphaloceles, there may be underlying pulmonary hypoplasia or tracheo-bronchial malacia that complicates ventilatory management. Following extubation most infants have feeding difficulties because of the prolonged period without oral stimulation and poor coordination of sucking and swallowing. In addition, many infants have high respiratory rates following omphalocele repair. Because of the compromised diaphragmatic excursion and chest wall motion, these infants maintain their minute ventilation by shallow, rapid breathing patterns. This rapid breathing often interferes with suckling, and gavage feeding may be necessary. Gastroesophageal reflux in these infants is common, which may require medical therapy, transpyloric feeding, or antireflux surgery.
As mentioned previously, the particular anomalies associated with omphalocele have a major impact on long-term outcome. This is especially true of chromosomal and cardiac defects. As survival rates of patients with omphalocele improve, more outcome data will become available, particularly with respect to other aspects that have an impact on the quality of life (Figure 6). Preliminary studies suggest that there are higher rates of behavioral problems and musculoskeletal abnormalities in children with abdominal wall defects (Ginn-Pease et al., 1991; Loder and Guiboux, 1993). Kaiser et al. (2000) suggest that a favorable long-term outcome can be anticipated, except in cases associated with severe congenital anomalies. There is one reported case of successful pregnancy in adulthood following the staged repair procedure for a large omphalocele (Ein and Bernstein, 1990).
- Genetics and Recurrence Risk
The recurrence risk depends on the cause of the omphalocele. If the fetus has a chromosomal abnormality due to aneuploidy, such as trisomy 18, the recurrence risk is 1% or the age-related maternal risk, whichever is higher. If a syndrome is diagnosed, the recurrence risk is that of the syndrome (Stoll et al., 2008). Familial cases of Beckwith–Wiedemann syndrome may have as high as a 50% recurrence risk. Nonsyndromal (isolated) omphalocele is generally considered to be a sporadic event, with a negligible recurrence risk. However, at least 17 cases of familial omphalocele have been described (Osuna and Lindham, 1976; DiLiberti, 1982; Pryde et al., 1992). Most of these families appear to transmit the gene as an autosomal dominant gene. In one asymptomatic patient, five consecutive pregnancies by two different nonconsanguineous partners were complicated by fetuses with isolated omphalocele (Pryde et al., 1992).
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Figure 1 A. Sagittal image demonstrating the intact sac of a liver containing omphalocele in a fetus at 15 weeks; B. pathologic appearance of a fetus with omphalocele due to defect in lateral folding. (Courtesy of Dr. Joseph Semple.)
Figure 2. Color Doppler ultrasound of a fetus at 17 weeks’ gestation with large omphalocele, demonstrating umbilical cord insertion into the membrane covering the abdominal wall defect.
Figure 3 A. Ultrasound image of fetus with ruptured omphalocele seen in sagittal plane, demonstrating large ventral defect through which the entire liver, stomach, and intestines have herniated. No membrane is seen around the defect. B. The appearance of the infant immediately postnatally, with completely exteriorized liver, stomach, and small and large bowel.
Figure 4. Silo repair of omphalocele.
Figure 5. Intraoperative appearance following closure of newborn abdomen after primary omphalocele repair. The umbilical artery has been transposed to a right lower quadrant site for umbilical artery catheter placement for arterial blood pressure monitoring.
Figure 6. Abdominal appearance 1 year after primary repair of a large omphalocele. Note the absence of a normal umbilicus.