Isolated abdominal wall defect to right of normally inserted umbilical cord.
Associated with young maternal age and maternal smoking.
Associated with growth restriction and abnormalities of amniotic fluid.
The efficacy of amnioexchange is under investigation.
Increased incidence of intrauterine fetal demise in the third trimester.
Intestinal atresia can complicate 10% to 15% of cases.
Gastroschisis (Greek for belly cleft) is a full-thickness defect in the abdominal wall that occurs secondary to incomplete closure of the lateral folds during the 6th week of gestation (Moore and Stokes, 1953; Moore and Persaud, 1993). At birth, the eviscerated bowel characteristically has a thick edematous appearance described by Moore as a “peel” (Figure 63-1). The peel involves the serosa and is composed of fibrin and collagen. The peel in gastroschisis is thought to be caused by an inflammatory reaction as a result of exposure to amniotic fluid, combined with constriction at the abdominal wall defect (Amoury and Holder, 1977; Klein et al., 1983; Tibboel et al., 1986a, b; Amoury et al., 1988; Langer et al., 1990; Moore, 1992). Duhamel (1963) theorized that gastroschisis originates from a discrete teratogenic insult that results in an isolated defect in differentiation of the somatopleural mesenchyme. Others argue that gastroschisis is due to an in utero rupture of an umbilical cord hernia after completion of the infold in the anterior abdominal wall, but before complete closure of the umbilical ring (Shaw, 1975). In at least some cases, in utero rupture of a hernia of the cord that resulted in gastroschisis supports the argument for this being a cause (Glick et al., 1985). DeVries (1980) suggested that gastroschisis could be caused by a congenital weakness on the right side of the umbilical cord. From an umbilical cord hernia, premature atrophy or abnormal persistence of the right umbilical vein could predispose to disruption of the somatopleura at its junction with the body stalk. Because gastrointestinal defects such as atresia associated with gastroschisis are caused by vascular disruptions, Hoyme et al. (1983) suggested that gastroschisis may be caused by disruption of the right omphalomesenteric artery, which connects the yolk sac with the dorsal aorta. The fact that gastroschisis almost always occurs to the right of the umbilical ring is consistent with these latter theories (Torfs et al., 1990).
Newborn infant with gastroschisis demonstrating characteristic “peel.”
As second trimester maternal serum-α-fetoprotein (MSAFP) screening has become incorporated into routine prenatal care, more cases of gastroschisis are being detected prenatally. This is due to the association between elevated MSAFP levels and ventral abdominal wall defects (McKeown et al., 1953; Brock et al., 1979; Redford et al., 1985; Stiller et al., 1990; Killam et al., 1991). In one study, Larson et al. (1993) found a 58% incidence of major fetal congenital anomalies when extremely elevated MSAFP levels were detected between 15 and 20 weeks of gestation. Ten percent of these were due to abdominal wall defects. The sensitivity of MSAFP screening for the detection of abdominal wall defects varies depending on the type of abdominal wall defect, the geographical area, and the cutoff value of MSAFP used.
MSAFP screening has a higher sensitivity for detecting gastroschisis than omphalocele. In a population-based study of MSAFP screening, using patients from Maine and Rhode Island, Palomaki et al. (1988) found that the combined incidence of gastroschisis and omphalocele was 4.5 in 10,000 livebirths (excluding neural tube defects, twins, and autosomal chromosomal anomalies). At each cutoff of MSAFP, detection rates were higher for gastroschisis than for omphalocele. For example, at a cutoff of 2 multiples of the mean (MoM), the detection rate was more than 99% for gastroschisis and 78% for omphalocele. At cutoff values of 2.5 MoM and 3 MoM, the detection rates were more than 98% and 71%, and 96% and 65%, for gastroschisis and omphalocele, respectively. The median MSAFP value of the 20 cases of gastroschisis was 7 MoM and the median value for omphalocele was 4.1 MoM (Palomaki et al., 1988). Crandall et al. (1991) have shown that the higher the MSAFP level the greater the prevalence of adverse fetal outcome. A lower detection rate in omphalocele is likely due to the presence of an intact membrane covering the abdominal viscera in unruptured omphaloceles as opposed to the direct exposure of bowel to the amniotic fluid in gastroschisis.
Analysis of amniotic fluid α-fetoprotein and acetylcholinesterase pseudocholinesterase levels (ratio 0.13) is very sensitive in detecting gastroschisis (Goldfine et al., 1989). Human chorionic gonadotropin (hCG) levels have been measured in 16 pregnancies with abdominal wall defects (12 gastroschises, 4 omphaloceles) because this marker is already being increasingly used for fetal aneuploidy screening. It may have utility as an additional marker for the presence of abdominal wall defects. Using a cutoff value of 2.3 MoM, the detection rate using hCG was 31%, as compared with 81% for MSAFP. Using the two markers, the detection rate increased to 87.5%, by finding one additional case (Schmidt et al., 1993). More data are necessary to evaluate the usefulness of hCG levels to prospectively identify abdominal wall defects.
Before 1953, gastroschisis was not clearly distinguished from omphalocele (Moore and Persaud, 1993). Consequently, a reliable estimate of the frequency of gastroschisis before then is impossible. Several investigators have found that the prevalence of gastroschisis has increased over the past few decades in different geographic regions (Hwang and Kousseff, 2004). Roeper et al. (1987) documented in California that the rate of gastroschisis has increased from 0.006 in 1000 livebirths in 1968 to 0.089 in 1000 livebirths in 1977. Similarly, Florida, Sweden, Finland, and Spain have reported increased prevalence rates over the same period (Lindham, 1981; Hemmenki et al., 1982; Martinez-Frias et al., 1984; Hwang and Kousseff, 2004). The overall prevalence in Europe has been reported to be 0.07 in 1000 live-and stillbirths (Calzolari et al., 1993). Studies from British Columbia and Italy have not confirmed this trend (Baird and MacDonald, 1981; Calzolari et al., 1993).
Both older and more recent data from epidemiologic studies have consistently demonstrated that young maternal age is associated with an increased risk of gastroschisis (Colombani and Cunningham, 1977; Hemmenki et al., 1982; Martinez-Frias et al., 1984; Roeper et al., 1987). Goldbaum et al. (1990) compared 62 infants who had gastroschisis with 617 randomly selected, unaffected infants matched for the first year of birth in the state of Washington. They found that maternal age younger than 20 years was associated with a fourfold increased risk of having an infant with gastroschisis. A study by Werler et al. (1992) included patients from Boston, Philadelphia, and portions of Ontario and Iowa. They compared 76 cases of gastroschisis with 2582 malformed controls and found a strong inverse association with maternal age. Compared with women 30 years or older, the relative risks for maternal ages 25 to 29, 20 to 24, and younger than 20 were 1.7, 5.4, and 16, respectively (Werler et al., 1992).
In addition to young maternal age, maternal cigarette use has also been associated with an increased risk of gastroschisis. Goldbaum et al. (1990) were the first to suggest this relationship. In a prospective population-based study using 62,103 consecutive second trimester MSAFP samples, Haddow et al. (1993) found that women who smoked had a 2.1-fold greater risk of fetal gastroschisis than nonsmokers. Although their finding was not considered statistically significant, the trend was consistent with the report by Goldbaum et al. (1990). In contrast, Werler et al. (1992) found no association with cigarette use in early pregnancy when heavy (more than 15 cigarettes per day) and light (less than 15 cigarettes per day) were compared. However, when the results of these three studies are combined, the relative risk for having a baby with gastroschisis is 1.6 for women who smoke (Haddow et al., 1993).
Although reports are conflicting, the incidence of gastroschisis has also been associated with seasonal variation. These studies found an increased risk of gastroschisis in deliveries occurring during the first quarter of the year (Egenaes and Bjerkedal, 1982; Hemmenki et al., 1982; Goldbaum et al., 1990). However, three other studies found no seasonal variation (Paulozzi, 1986; Roeper et al., 1987; Haddow et al., 1993). Vascular disruption has been suggested by cases of gastroschisis observed in women who took medications with vasoactive properties during pregnancy (Van Allen, 1981). In a prospective screening study of maternal hair samples using gas chromatography with mass spectroscopy, Morrison et al. (2005) found a 25% incidence of periconceptual recreational drug use. The most commonly detected compounds were methamphetamine, including MDMA and MDEA, and cocaine. There is good evidence from animal data that methamphetamines cause fetal malformations including cardiac defects, facial clefts, eye abnormalities, skeletal malformations, kidney defects, and gastroschisis (Colado et al., 1997; Plessinger, 1998). Amphetamines and cocaine have similar maternal effects, as they are both central nervous system stimulants. They produce different fetal developmental effects (Little et al., 1988). Werler et al. (1992) reported on first trimester medication use in a case–control study of 76 cases of gastroschisis and 2142 matched controls. They found that the decongestant pseudoephedrine was associated with a greater than threefold risk of gastroschisis. Salicylates and acetaminophen were also associated with elevated risk, but these differences were not statistically significant. The authors also evaluated the use of these medications in pregnancies with other fetal anomalies that were presumed to have a vascular cause; no associations were found. Further studies are needed to clarify the role of vasoactive agents in the pathogenesis of gastroschisis.
The diagnosis of abdominal wall defects during the first trimester is difficult because it is normal for the midgut to be herniated into the umbilical cord. Cyr et al. (1986) documented the events of bowel migration by abdominal sonographic examination of 10 normal first trimester fetuses, as well as by pathologic examination of several embryo specimens. The midgut that will normally form the small bowel, cecum, and ascending and proximal transverse colon is connected to the yolk sac. This connection is reduced to a narrow yolk stalk as the amniotic cavity expands and the yolk sac is pulled away from the embryo. The mesentery suspending the midgut then rapidly elongates, creating a U-shaped loop of midgut that herniates into the umbilical cord. The loop of intestine then rotates 90 degrees in a counterclockwise direction about the axis of the superior mesenteric artery. As these loops of bowel return to the abdominal cavity by 11 weeks of gestation, the loops rotate counterclockwise another 180 degrees to complete the bowel rotation. Cyr et al. (1986) have suggested that ultrasound examination should be performed at 14 weeks of gestation because the bowel should be entirely intra-abdominal by 11 weeks, and this allows for errors in estimating gestational age. However, in 20% of fetuses, the bowel was still outside the abdomen at 12 weeks (Green and Hobbins, 1988). The size of the herniated gut may be helpful in distinguishing between physiologic and pathologic bowel herniation. The dimensions of bowel herniation have been reported to be 1 cm in the study by Cyr et al. (1986) and 7 mm in greatest dimension in the study by Bowerman (1993).
Vaginal sonography affords a closer look at the fetus in early gestation and may be helpful in distinguishing the contents of the herniation. In a series of 61 fetuses studied by vaginal sonography, by 12 weeks of gestation the midgut herniation no longer persisted (Timor-Tritsch et al., 1989). The earliest diagnosis of gastroschisis was 12 weeks 3 days (Guzman, 1990).
Gastroschisis is a full-thickness defect in the anterior abdominal wall almost invariably located to the right of the intact umbilical cord, measuring 2 to 3 cm in diameter (Figure 63-2) (Fonkalsrud, 1980). Color Doppler studies assist in demonstrating normal umbilical cord insertion with herniation of intestine to the right of the umbilical cord. Nyberg et al. (1993) have summarized the sonographic features of gastroschisis. In addition to the small abdominal wall defect located to the right of a normal umbilical cord insertion site, there is a variable amount of bowel protruding through the defect, floating in the amniotic fluid, which may be disproportionally large relative to the small size of the abdominal cavity (Figure 63-3).
Color flow Doppler image in fetus with gastroschisis, demonstrating small defect with herniated midgut.
Prenatal ultrasound image demonstrating loops of intestine floating free in amniotic fluid.
Despite the frequent use of antenatal ultrasound examination in obstetric care over the past two decades, there is still little information regarding the accuracy of routine ultrasound examination in the detection of abdominal wall defects (Hill et al., 1985; Rosendahl and Kivinen, 1989; Ewigman et al., 1993). Walkinshaw et al. (1992) reported on their experience in the United Kingdom for more than a 4-year period, extending from 1984 to 1988, during which 115 cases of anterior abdominal wall defects were found in 202,488 livebirths and intrauterine deaths beyond 22 weeks of gestation. They found that routine scanning identified 60% of the defects, with a false-positive rate of 5.3%. Gastroschisis and omphalocele were accurately distinguished in 79.3% of cases on initial diagnosis and 84.5% of cases after referral for further evaluation. Many factors contribute to the less than 100% detection of abdominal wall defects, including the quality of the ultrasound equipment, the experience of the sonographer, and the defect itself (Paidas et al., 1994). It is possible that one form of gastroschisis, due to rupture of a hernia of the cord as originally described by Moore (1962), would not be detected by routine ultrasound examination because it appears late in pregnancy. Knott and Colley (1987) have described two similar cases of gastroschisis not detected by antenatal ultrasound examination that were felt to occur as a result of late gestational rupture of a hernia of the cord.
The differential diagnosis of gastroschisis should include omphalocele, ruptured omphalocele, hernia of the cord, and limb–body wall complex. Gastroschisis is distinguished from omphalocele by having no membrane surrounding the herniated loops of intestine. In contrast, omphalocele has a peritoneo-amniotic membrane covering the defect and the size is significantly larger than the defect in gastroschisis. Ruptured omphalocele may be confused with gastroschisis, as the loops of intestine are observed to be floating free in the amniotic cavity. However, extracorporeal liver may be seen in ruptured omphalocele, but is never seen in gastroschisis. The limb–body wall complex may have an abdominal wall defect but is usually easily distinguished from gastroschisis by a short umbilical cord and numerous other associated structural anomalies.
ANTENATAL NATURAL HISTORY
The conventional wisdom regarding abdominal wall defects is that gastroschisis, unlike omphalocele, is not associated with chromosomal abnormalities. This discrepancy regarding the presence of associated chromosomal abnormalities has provided further impetus to distinguish these two entities by sonography. Reports in the literature have confirmed that chromosomal abnormalities are rare or absent in gastroschisis (Mayer et al., 1980; Mann and Ferguson-Smith, 1984; Sermer et al., 1987; Romero et al., 1988; Lewinsky et al., 1990; Sipes et al., 1990a). In the 17-year experience at the Children’s Hospital in Columbus, Ohio, chromosomal analysis was available in 128 of 144 cases of gastroschisis and there was only 1 case of chromosomal abnormality (trisomy 18) (King et al., 1980; Caniano et al., 1990). Nicolaides et al. (1992) did not find any chromosomal abnormalities in 26 cases of gastroschisis detected during an 8-year period. Abdullah et al. (2007) found only four cases (0.1%) of aneuploidy among 4344 infants with gastroschisis in the United States. In the absence of sonographically detectable associated anomalies, the risks for fetal aneuploidy are probably comparable to the risks due to maternal age alone. If additional fetal abnormalities are detected sonographically, chromosomal evaluation should be recommended.
In contrast to omphalocele, gastroschisis is usually not associated with extra gastrointestinal abnormalities. This is in part responsible for the better outcome observed in gastroschisis. In a survey of 13 years of the National Inpatient Sample Database and 3 years of the KIDs’ Inpatient Database, Abdullah et al. found among 4344 cases of gastroschisis reported only 72 (1.7%) cases of pulmonary defects (including agenesis, hypoplasia, and bronchopulmonary dysplasia) and 379 cardiac defects, of which 190 were atrial septal defects (ASDs) and 214 patent ductus arteriosus cases that would not be detectable on prenatal ultrasound examination. There were also 138 cases of undescended testicles (6.8%) and 58 cases of hydronephrosis (1.3%) (Abdullah et al., 2007). However, in a report from Kunz et al. (2005) in a study of California hospital discharge data from 1972 to 1997, 25 of 621 infants with gastroschisis were found to have congenital heart disease (4% incidence). This group also found a significant increase of congenital heart disease if the gastroschisis was complicated by bowel atresia, or if the infant was African American. Gibbin et al. found an incidence of abnormal cardiac findings of 15%, but of the four, one was persistent pulmonary hypertension, two were supraventricular tachycardia, and the last was peripheral pulmonic stenosis (Gibbin et al., 2003). However, gastrointestinal anomalies can commonly be seen in gastroschisis, and occur in 20% to 40% of cases (King et al., 1980; Mayer et al., 1980; DeLorenzo et al., 1987; Nicolaides et al., 1992; Novotny et al., 1993). These gastrointestinal abnormalities may be secondary to the gastroschisis. These include malrotation, atresia, “Christmastree deformity,” volvulus, and infarction.
Even in the rare cases in which they are present, nongastrointestinal abnormalities are not usually life-threatening. It is interesting that the data registry report from Abdullah et al. (2007) had a lower than expected 8.1% incidence.
Fetuses with gastroschisis are at risk for a number of complications that directly affect survival during the newborn period. Obstetric complications include intrauterine growth restriction (IUGR), which can affect up to 77% of fetuses (Carpenter et al., 1984; Molenaar and Tibboel, 1993). This may be due to nutritional deprivation rather than a constitutional limitation (Gutenberger et al., 1973). In an analysis of biometric data Royner and Richards (1977) found that IUGR was predicted in 43% of infants, but was present in only 23% at birth. This group thought that the prevalence of IUGR is increased in gastroschisis, but is overestimated with prenatal ultrasonography, primarily because of the smaller-than-average abdominal circumference. Carroll et al. (2001) suggested a novel explanation for the frequent observation of growth restriction among fetuses with gastroschisis; protein loss into the amniotic cavity. In a small series of 12 fetuses with prenatally diagnosed gastroschisis were compared with 29 control infants without gastroschisis. They found that fetuses with gastroschisis had significantly lower serum total protein and significantly higher amniotic fluid total protein, and α-fetoprotein.
Despite the predisposition to IUGR, a more important factor in neonatal outcome is prematurity. Puligandla et al. (2004) found that in a retrospective series of 113 cases of gastroschisis, infants with IUGR had similar outcomes to non-IUGR infants. Factors that were more important with regard to neonatal outcome were prematurity and the presence of atresia (Puligandla et al., 2004).
Other obstetric complications include preterm labor, which occurs in more than one-third of cases due to associated polyhydramnios (Mayer et al., 1980; Kirk and Wah, 1983; Carpenter et al., 1984; Caplan and MacGregor, 1989; Molenaar and Tibboel, 1993). Abnormalities of amniotic fluid volume, both polyhydramnios and oligohydramnios, can accompany gastroschisis (Bair et al., 1986; Crawford et al., 1992). Mercer et al. (1988) reported that in their series of 22 cases of gastroschisis, marked amniotic fluid staining occurred in 73%. The association of amniotic fluid staining with fetal distress is controversial (Carpenter et al., 1984; Crawford et al., 1992).
Because the condition of the bowel at the time of birth is the single most important factor affecting long-term outcome for fetuses with gastroschisis, several investigators have monitored the ultrasonographic appearance of the bowel (Stringel and Filler, 1978; Luck et al., 1985). The extent of bowel damage is variable in gastroschisis and can range from only mild to severe, with bowel atresia and necrosis requiring resection with staged repair. These latter cases are often characterized on sonography by extreme intestinal hypoperistalsis and poor absorptive capacity (O’Neill and Grosfeld, 1974; Oh et al., 1978). Although the cause of bowel damage is not entirely understood, it seems that most of the damage is caused by constriction at the site of the abdominal wall defect and that this occurs primarily late in gestation (Langer et al., 1989, 1990). Based on experimental findings in fetal lambs, Langer et al. (1993) suggested that the mechanism of constriction-induced damage is related mainly to obstruction and not ischemia.
Bond et al. (1988) published a series of 11 cases of gastroschisis correlating the prenatal ultrasonographic appearance of the eviscerated bowel with clinical outcome. The presence of small-bowel dilation and mural thickening correlated with severe intestinal damage and poor clinical outcome. The absence of these findings was associated with a more benign clinical course. These authors suggested that these two ultrasonographic features—bowel dilatation and bowel thickening—could be useful in following fetuses with gastroschisis and in determining the time of delivery. Other reports have not found these findings to be at all predictive of outcome in gastroschisis (Lenke et al., 1990; Sipes et al., 1990b; Alsulyman et al., 1996). Early detection of signs of bowel damage would allow delivery at fetal lung maturity to prevent ongoing injury to the bowel and decrease the likelihood of hypoperistalsis syndrome. Three small series have not found that these two characteristics were useful in predicting outcome (Lenke et al., 1990; Sipes et al., 1990b; Alsulyman et al., 1996).
In a combined retrospective and prospective study, Langer et al. (1993) evaluated 24 fetuses with gastroschisis and found that bowel thickening was associated with an increased time to oral feeding, but this finding did not achieve statistical significance, possibly due to the small number of patients. As opposed to using a specific cutoff for bowel damage, these authors suggested using a value that had a specific threshold for gestational age. From their own data, fetuses above this threshold value had hypoperistalsis and below it only 30% had a hypoperistalsis. Interestingly, Aina-Mumuney et al. (2004) have noted that a dilated fetal stomach found in 13 of 34 prenatally diagnosed cases of gastroschisis was associated with a statistically significant greater incidence of nonreactive nonstress tests, volvulus, neonatal death, as well as delayed time to full oral feeding and longer hospitalization, compared to those that did not have a dilated stomach (Aina-Mumuney et al., 2004).
A disturbingly high incidence of intrauterine fetal demise and stillbirth during the third trimester has consistently been reported, with rates as high as 10.6% (Crawford et al., 1992; Burge and Ade-Ajayi, 1997). Broth et al. (2001) reported that among 78 cases of gastroschisis, the stillbirth rate after 28 weeks’ gestation was 85 per 1000 births compared to a control group rate of 5.4 per 1000 births. The cause of stillbirth is thought to be either midgut volvulus or progressive cord compression by eviscerated bowel. Kalache et al. (2002) reported a case of gastroschisis complicated by sudden dilation of the bowel at 34 weeks’ gestation with the development of notching of the umbilical artery waveform. This was thought to be due to compression, which has previously been reported with stomach herniation in gastroschisis (Robinson et al., 1997). Notching of the umbilical arterial Doppler waveform has also been observed in cord entanglement in monoamniotic twins (Kofinas et al., 1991). This sign should be looked for in third trimester fetuses with gastroschisis as an indicator for nonstress testing.
Although fetal imaging has not provided useful prognostic indicators of severity of gastroschisis, it is possible that amniotic fluid levels of β endorphins may. Mahieu-Caputo et al. (2002) have found that amniotic fluid β endorphin levels above 10 μg/L (n =4) versus 5 μg/L (n =9) correlated with longer duration of ventilation, parenteral nutrition, and duration of hospitalization. These investigators speculated that elevated β endorphin levels could result from fetal stress caused by bowel damage.
Crawford et al. (1992) have recommended biophysical profile testing for pregnancies with gastroschisis because they found a 12.5% rate of stillbirths. Because these deaths occurred late in the third trimester, they suggested that testing begin at 30 to 32 weeks of gestation.
We are currently monitoring our cases of gastroschisis with biophysical testing beginning at 30 weeks’ gestation, and by performing weekly sonography to assess bowel thickness, dilation, evidence of increased peristalsis, or dilated stomach. If sonographic evidence of bowel damage is detected, consideration can be given to delivery as soon as the lungs mature to prevent ongoing injury. However, detection of bowel dilation alone may be due to atresia, in which case delivery will have no benefit.
The recommended mode of delivery for fetuses with abdominal wall defects is controversial. Part of the difficulty in comparing the vaginal versus abdominal approach is the presence of multiple confounding factors, such as antenatal diagnosis of lesion, presence or absence of labor, maternal and neonatal transport, interval between delivery and surgery, and place of delivery. Kirk and Wah (1983) reported 74 cases of gastroschisis, 65 of which were delivered vaginally and 9 by cesarean section. There were five deaths in each group, resulting in a much higher mortality rate for fetuses delivered by cesarean section. Lenke and Hatch (1986) retrospectively reviewed their series of 24 cases of gastroschisis. Seven of 24 infants were delivered by cesarean section and all had a good outcome. There were 3 deaths among the remaining 17 delivered vaginally. Only 11 of the 17 cases of gastroschisis were able to have primary closure, as opposed to all of the infants delivered by cesarean section. These authors also commented that in all infants delivered by cesarean, there was no evidence of the inflammatory “peel,” or inflamed serosa, on the eviscerated bowel seen in the worst cases of gastroschisis. Moretti et al. (1990) reported on 56 fetuses with gastroschisis, and did not find any differences in infant mortality, short- or long-term outcome, or frequency of associated major anomalies. However, in their experience, only 8% of the defects were detected antenatally. Other authors did not find any benefit to abdominal delivery (Kirk and Wah, 1983; Carpenter et al., 1984; Davidson et al., 1984; Calisti et al., 1987; Sermer et al., 1987; Sipes et al., 1990a; Puligandla et al., 2004). In an attempt to control for confounding variables, Lewis et al. (1990) reviewed their experience with 56 cases at level-three institutions and found no benefit to cesarean delivery. Coughlin et al. (1993) have reported the results of a trial of cesarean delivery with staff standing by in an adjacent operating room for immediate repair of the gastroschisis. In this small series of cases, cesarean delivery and immediate repair were associated with a greater rate of primary closure, a shorter period of mechanical ventilatory support, and a shorter interval to enteral alimentation, as compared with historical controls delivered vaginally who underwent more routine gastroschisis repair. As demonstrated in these reports, at present there is no compelling evidence for cesarean over vaginal delivery in gastroschisis except for routine obstetrical indications.
The neonatal outcomes in gastroschisis do not appear to be adversely affected by labor or rupture of membranes (Strauss et al., 2003). However, some have suggested that it is the timing, not the mode of delivery that results in improved outcome (Lenke and Hatch, 1986; Moore, 1988, 1992; Swift et al., 1992; Langer, 2003). These authors mention that most of the bowel injury occurs late in gestation, which may be avoided with early delivery. We recommend transferring the mother to a tertiary care center before delivery to better coordinate the obstetric, neonatal, and pediatric surgical teams (Carlan et al., 1990; Nicholls et al., 1993; Stoodley et al., 1993; Paidas et al., 1994).
In patients managed by vaginal delivery as opposed to elective cesarean section, continuous cardiotocography may be helpful in identifying fetal distress (Brantberg et al., 2004). In a series of all patients prenatally diagnosed with gastroschisis at the National Center for Fetal Medicine in Norway, Brantberg et al. found that cardiotocographic monitoring detected abnormalities in 22% of 64 fetuses. There was only a single case of intrauterine fetal demise (IUFD) in the series. They attributed the improved outcome to better detection of fetal distress.
There is currently no accepted fetal intervention for gastroschisis. However, there is interest in some centers for the use of amnioexchange to improve bowel function in gastroschisis. The rationale for this approach is that bowel damage occurs in utero from two mechanisms: constriction at the abdominal wall (Langer et al., 1989, 1990) and chemical irritants in the amniotic fluid, which stimulate an inflammatory response in bowel serosa (Langer et al., 1989; Albert et al., 1993; Luton et al., 2003). The first published case of amnioexchange to treat fetal gastroschisis was reported by Aktug (Aktuǧ et al., 1995), with four amnioexchanges between 29 and 34 weeks of gestation. Enteral nutrition was achieved by 5 days and the infant was discharged to home at day 8.
Based on favorable results in a fetal sheep model demonstrating improved serosal fibrosis, decreased inflammatory cell infiltration and clearance of inflammatory and gastrointestinal waste product (Luton et al., 2000; Thebaud et al., 2002), Luton et al. (2003) conducted a pilot study in human gastroschisis. Amnioexchanges start at 30 weeks of gestation via transabdominal amniotic fluid drainage through a 20-gauge needle. Amniotic fluid is replaced serially 300 mL by 300 mL with warm sterile saline, for a total of 600 to 900 mL replaced at each procedure. Compared to a historical control group, the amnioexchange group had the same mean gestational age at delivery (36.9 ± 1.3 weeks), without chorioamniotic or premature rupture of membranes in the first 30 patients treated.
Analysis of the first 10 patients showed a nonsignificant trend for less severe perivisceritis, reduced time on mechanical ventilation, need for hospitalization, and hospital stay. The authors contend that if extrapolated to the full 30 patients, these trends would achieve statistical significance. This same group reported a favorable effect of amnioexchange on the extra-abdominal mesenteric artery Doppler index (Volumenie et al., 2001). There was, however, no correlation with postnatal outcome. Amnioexchange does not address the constrictive effects at the abdominal wall. As these investigations acknowledge, the data thus far do not prove efficacy of amnioexchange. The problem with this approach is not the rationale for amnioexchange nor the potential for amnioexchange to reduce perivisceritis. Rather, the weakness lies in the lack of selection criteria. Most newborns with gastroschisis do not have severe perivisceritis or inflammatory peel and they do very well with conventional postnatal treatment. There is a subset of gastroschisis patients (representing 10%–15% of cases) in which there is a severe inflammatory peel, protracted need for parenteral nutrition, compromised gut mobility and prolonged hospitalization. Until accurate sonographic criteria are developed to identify this subset of fetuses with gastroschisis, it is unlikely that anmioexchange will improve outcome and has the potential to expose patients to the risk of this intervention with little hope of benefit.
At delivery, the infant’s lower body should be placed in a clear plastic bowel bag to minimize evaporative losses. The exposed bowel should be kept moist and handled in a sterile fashion. The intestines should be supported by bolsters of rolled gauze placed on either side of the abdominal wall defect to prevent kinking at the abdominal wall, which would result in venous congestion and subsequent acidosis. The infant should be placed in the right lateral decubitus position to minimize the chances of obstruction at the abdominal wall. The bowel should be covered with nonadherent sterile petroleum gauze and wrapped in sterile dry gauze and placed in a Lahey bag. A nasogastric tube should be inserted and placed for suction to prevent bowel distention from swallowing air. Venous access should be obtained in the upper extremities, antibiotics (ampicillin and gentamicin) should be administered, and crystalloid infusion begun as soon as possible to replace ongoing third-space losses. It is not uncommon for these newborns to become quite dehydrated because of the excessive evaporative losses of the exposed viscera. Adequate volume resuscitation is essential for proper treatment and prevention of necrotizing fasciitis.
Success has been achieved with both primary closure and staged silo reduction, with the surgery tailored to each individual case (Ein and Rubin, 1980; King et al., 1980; Luck et al., 1985; DeLorenzo et al., 1987; Caniano et al., 1990; Novotny et al., 1993). No matter which operative strategy is employed, the infant is nutritionally supported by parenteral nutrition delivered via PICC line or broviac. The advantages of primary closure are shorter intervals to oral feeding, reduced hospital stay, and the lack of further extensive surgery. However, the success of primary closure depends on the degree of visceroabdominal disproportion. Excessive abdominal wall tension can cause vena caval compression, compromised respiratory function, postrenal oliguria from ureteral obstruction, and even bowel ischemia. Intragastric pressure and central venous pressure recordings have been advocated to detect excessively high intra-abdominal pressures during attempted closure (Yaster et al., 1989). In a review of 30 cases of gastroschisis, Bryant et al. (1985) found that the interval to return to oral alimentation was not related to the type of closure.
The risk of ongoing evaporative water loss, heat loss, and metabolic derangements that occur as a result makes rapid coverage of the bowel a priority (Ledbetter, 2006). In the delivery room or upon arrival in the NICU, the bowel can be placed in a prefabricated, spring-loaded, silastic silo. These preformed silos can be placed at the bedside without anesthesia. If the fascial ring is too small, the defect can be enlarged with local anesthesia and sedation (Minkes et al., 2000). The placement of a prefabricated silo converts the operative closure to an elective procedure once the gravity has reduced the bowel edema, allowing bowel loops to return to the abdominal cavity. This process usually takes 5 to 7 days and can be facilitated by gently reducing the bowel and placing an umbilical tape tie to keep the bowel reduced. The process can usually be accomplished without the need for the infant to be intubated, ventilated, or the use of muscle relaxants. Once the bowel has been completely reduced, the infant is taken to the operating room for a delayed primary closure of the fascia.
Introduction of the silo by Schuster (1967) was a major advance in management of gastroschisis with severe visceroabdominal disproportion. Creation of a silo sutured to the fascia can be performed as a primary procedure or if reduction with a preformed silo is unsuccessful. The viscera are gradually reduced into the abdomen by sequential tightening of the silastic silo (Figure 63-4). The goal of this therapy is the gradual reduction of viscera over 3 to 5 days. After 7 days, the risks of infection with this technique increase significantly. The infant may be intubated and neuromuscular paralysis induced to allow maximal relaxation of the abdominal wall. Once all of the viscera are reduced, the infant is returned to the operating room, where the silastic silo is removed and a fascial closure is performed. Other methods of closure useful in selected cases include extensive skin flaps, umbilical cord patch, Ringer clamp, or Gore-Tex patch closure (Muraji et al., 1989; Zivkovle, 1991; Sawin et al., 1992; Stringel, 1993).
Intraoperative view during creation of silo for staged closure of gastroschisis.
Potential postoperative complications are numerous and include intestinal ischemia, bowel infarction, enterocutaneous fistula, necrotizing enterocolitis, and prolonged intestinal dysfunction (Ein et al., 1988; Oldham et al., 1988; Caniano et al., 1990). Intestinal atresia can complicate gastroschisis, and is reported to occur in 5.5% to 23% of patients (Amoury and Holder, 1977; Pokorny et al., 1981; DeLorenzo et al., 1987; Gornall, 1989; Shah and Woolley, 1991). These may be single or multiple, and may involve the small or large bowel.
The primary goal in gastroschisis complicated by atresia is abdominal wall closure either by primary closure, use of prefabricated silo, or operative silo creation. Even if the atresia is recognized, no attempt should be made at resection of the atresia as the bowel is usually edematous and inflamed. Resection and primary anastomosis are at high risk for breakdown. By 2 weeks following primary repair of the abdominal wall defect, there is complete resolution of edema, inflammation, and peel, making resection and anastomosis readily accomplished (Snyder et al., 2001). Even in the rare instance in which there is perforation at the time of delivery, the proximal and distal bowel should be ligated. There should be at least a 2-week interval from abdominal wall repair to resection of atresia and primary repair.
The duration of hospitalization is directly related to the degree of gastrointestinal compromise or presence of gastrointestinal atresia. Some patients with gastroschisis will have hypoperistalsis syndrome. These infants remain dependent on parenteral nutrition for an indefinite period, sometimes permanently. The average hospital stay following closure of gastroschisis is usually on the order of 3 to 4 weeks. Often feeding difficulties after repair of gastroschisis will delay discharge because of the need for gavage feedings. Although primary closure may be achieved and infants are weaned from mechanical ventilatory support, they often remain quite tachypneic, which impairs their ability to suck. Once further abdominal wall relaxation and accommodation has had time to occur, there is less tension and pressure on the diaphragm and the respiratory rate decreases. Once a respiratory rate of less than 70 breaths per minute is achieved, infants can suck effectively and be weaned from supplemental gavage feeding.
Hospitalization for infants with gastroschisis requiring a repair of an atresia can be longer, related to the need for a second procedure to address the atresia. The hospitalization in these infants may be prolonged by several weeks.
There are usually no long-term sequelae from gastroschisis if there is no associated hypoperistalsis syndrome (Lunzer et al., 2001). Inguinal hernias will develop not uncommonly in infants with gastroschisis because of increased intra-abdominal pressure. Occasionally, incisional hernias seen as bulging from attenuated fascia at the closure site will require remedial surgery months or years later.
GENETICS AND RECURRENCE RISK
Gastroschisis has been generally considered to be a sporadic event, with a multifactorial cause, but there have been reports of familial recurrence (Salinar et al., 1979; Lowry and Baird, 1982; Hershey et al., 1989; Schmidt et al., 2005). Torfs et al. (1990) described a 4.3% sibling recurrence rate in a population-based study. An approximately 4% recurrence risk implies a mixture of genetic predisposition with environmental factors (Torfs and Curry, 1993). A single-gene defect is unlikely for this condition. Families should receive genetic counseling regarding recurrence risk. They should be offered MSAFP testing and prenatal sonography in future pregnancies.
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