Complex gastroschisis: a new indication for fetal surgery?

Gastroschisis (GS) is a congenital abdominal wall defect, in which the bowel eviscerates from the abdominal cavity. It is a non-lethal isolated anomaly and its pathogenesis is hypothesized to occur as a result of two hits: primary rupture of the 'physiological' umbilical hernia (congenital anomaly) followed by progressive damage of the eviscerated bowel (secondary injury). The second hit is thought to be caused by a combination of mesenteric ischemia from constriction in the abdominal wall defect and prolonged amniotic fluid exposure with resultant inflammatory damage, which eventually leads to bowel dysfunction and complications. GS can be classified as either simple or complex, with the latter being complicated by a combination of intestinal atresia, stenosis, perforation, volvulus and/or necrosis. Complex GS requires multiple neonatal surgeries and is associated with significantly greater postnatal morbidity and mortality than is simple GS. The intrauterine reduction of the eviscerated bowel before irreversible damage occurs and subsequent defect closure may diminish or potentially prevent the bowel damage and other fetal and neonatal complications associated with this condition. Serial prenatal amnioexchange has been studied in cases with GS as a potential intervention but never adopted because of its unproven benefit in terms of survival and bowel and lung function. We believe that recent advances in prenatal diagnosis and fetoscopic surgery justify reconsideration of the antenatal management of complex GS under the rubric of the criteria for fetal surgery established by the International Fetal Medicine and Surgery Society (IFMSS). Herein, we discuss how conditions for fetoscopic repair of complex GS might be favorable according to the IFMSS criteria, including an established natural history, an accurate prenatal diagnosis, absence of fully effective perinatal treatment due to prolonged need for neonatal intensive care, experimental evidence for fetoscopic repair and maternal and fetal safety of fetoscopy in expert fetal centers. Finally, we propose a research agenda that will help overcome barriers to progress and provide a pathway toward clinical implementation. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Ultrasound markers for prediction of complex gastroschisis and adverse outcome: longitudinal prospective nationwide cohort study.

OBJECTIVES: To identify antenatal ultrasound markers that can differentiate between simple and complex gastroschisis and assess their predictive value. METHODS: This was a prospective nationwide study of pregnancies with isolated fetal gastroschisis that underwent serial longitudinal ultrasound examination at regular specified intervals between 20 and 37 weeks' gestation. The primary outcome was simple or complex (i.e. involving bowel atresia, volvulus, perforation or necrosis) gastroschisis at birth. Fetal biometry (abdominal circumference and estimated fetal weight), the occurrence of polyhydramnios, intra- and extra-abdominal bowel diameters and the pulsatility index (PI) of the superior mesenteric artery (SMA) were assessed. Linear mixed modeling was used to compare the individual trajectories of cases with simple and those with complex gastroschisis, and logistic regression analysis was used to estimate the strength of association between the ultrasound parameters and outcome. RESULTS: Of 104 pregnancies with isolated fetal gastroschisis included, four ended in intrauterine death. Eighty-one (81%) liveborn infants with simple and 19 (19%) with complex gastroschisis were included in the analysis. We found no relationship between fetal biometric variables and complex gastroschisis. The SMA-PI was significantly lower in fetuses with gastroschisis than in healthy controls, but did not differentiate between simple and complex gastroschisis. Both intra- and extra-abdominal bowel diameters were larger in cases with complex, compared to those with simple, gastroschisis (P < 0.001 and P < 0.005, respectively). The presence of intra-abdominal bowel diameter ≥ 97.7th percentile on at least three occasions, not necessarily on successive examinations, was associated with an increased risk of the fetus having complex gastroschisis (relative risk, 1.56 (95% CI, 1.02-2.10); P = 0.006; positive predictive value, 50.0%; negative predictive value, 81.4%). CONCLUSIONS: This large prospective longitudinal study found that intra-abdominal bowel dilatation when present repeatedly during fetal development can differentiate between simple and complex gastroschisis; however, the positive predictive value is low, and therefore the clinical usefulness of this marker is limited. © 2019 Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal sonography of extracorporeal ductus venosus in association with large fetal gastroschisis.

Liver herniation commonly associated with omphalocele occurs in only approximately 2.3% to 16% of fetuses with gastroschisis. Liver herniation in such cases is associated with considerably decreased survival rates (43% vs 97% with or without liver herniation, respectively). Rarely, abnormally positioned fetal hepatic vasculature has been reported mainly in association with congenital diaphragmatic hernia. In these rare cases, intrathoracic depiction of hepatic venous vasculature has assisted in confirming intrathoracic displacement of the fetal liver. We present a case of a large gastroschisis with complete herniation of the fetal liver in which prenatal sonography depicted an extracorporeal ductus venosus.

High risk of spontaneous preterm birth among infants with gastroschisis.

We examined the association between gastroschisis and preterm birth (PTB, <37 weeks) by subtype. The sample was drawn from singleton live births in California from 2007 to 2012 contained in a birth cohort file maintained by the California Office of Statewide Health Planning and Development (n = 2,891,965; 1,421 with gastroschisis). Relative risks (RRs) and 95% confidence intervals (CIs) were calculated for PTB by gestational age (<34, 34-36, and any <37 weeks) and by type (spontaneous labor with intact membranes, preterm premature rupture of the membranes [PPROM], provider initiated) and were adjusted for maternal characteristics. Over 44.5% of infants with gastroschisis were born preterm because of spontaneous etiologies; notably, 8.4% of infants with gastroschisis were born <34 weeks because of spontaneous etiologies (adjusted RRs 9.1-12.2). Overall, 53.7% of infants with gastroschisis were born preterm compared with only 6.9% of infants without gastroschisis (adjusted RR 15.2, 95% CI 13.6-19.5) and are at particularly high risk of spontaneous PTB. Nearly 9% of infants with gastroschisis delivered <34 weeks, regardless of preterm etiology, indicating that these infants are at great risk for PTB morbidities in addition to the complications from gastroschisis.

Fetal intra-abdominal bowel dilation in prediction of complex gastroschisis.

OBJECTIVE: To investigate intra-abdominal bowel dilation (IABD) in the prediction of complex gastroschisis. METHODS: This was a retrospective study of 174 singleton pregnancies with isolated fetal gastroschisis, resulting in live birth and with available ultrasound images from visits at both 20-22 and 30-32 weeks' gestation. IABD was measured as the greatest transverse diameter of the most dilated intra-abdominal bowel segment, by an operator blinded to postnatal outcome. The distribution of IABD measurements in those with complex and those with simple gastroschisis was determined and the best cut-off value to predict complex gastroschisis was selected using receiver-operating characteristics (ROC) curves. The area under the ROC curve (AUC), detection rate (DR), false-positive rate (FPR), positive predictive value (PPV) and negative predictive value (NPV) were determined. RESULTS: The study population included 39 (22.4%) cases of complex and 135 (77.6%) cases of simple gastroschisis. In the prediction of complex gastroschisis, the AUC at 20-22 weeks' gestation was 0.742 (95% CI, 0.628-0.856) and the respective value for 30-32 weeks was 0.820 (95% CI, 0.729-0.910). At the IABD cut-off of 7 mm at 20-22 weeks, DR, FPR, PPV and NPV for complex gastroschisis were 61.5%, 6.7%, 72.7% and 89.4%, respectively, and at IABD cut-off of 14 mm at 30-32 weeks, the respective values were 64.9%, 5.9%, 75.0% and 90.7%. CONCLUSION: Measurement of IABD at 20-22 or at 30-32 weeks' gestation is useful in the prediction of complex gastroschisis. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Gestational Outcomes of Pregnancies with Prenatally Detected Gastroschisis and Omphalocele.

Objective: To evaluate and compare the outcomes of pregnancies with prenatally detected gastroschisis and omphalocele. Materials and Methods: We retrospectively evaluated prenatally detected gastroschisis and omphalocele cases. Cases were compared in terms of maternal demographic and clinical characteristics as well as pregnancy and neonatal outcomes. Results: This study consisted of 17 gastroschisis and 30 omphalocele cases. Only one case with gastroschisis was terminated due to additional severe limb deformities. Seventeen out of 30 cases of omphalocele were terminated for various reasons (56.7%). All patients with gastroschisis had surgical repair, while 8 out of 13 omphalocele cases had surgery. One patient with an omphalocele died after surgery due to sepsis. Six cases of gastroschisis also died in the neonatal period due to various reasons (6/16, 37.5%). Conclusion: Additional genetic disorders are more frequent in those with omphalocele cases, and they are more frequently terminated during gestation that the gastroschisis fetuses.

Registry analysis supports different mechanisms for gastroschisis and omphalocele within shared developmental fields.

Nine thousand two hundred eighty abnormalities associated with 2,943 abdominal wall defects (AWD) encoded from 1999 to 2008 by the Texas Birth Defects Registry (TBDR) were classified and analyzed for mechanism, beginning with 1,831 gastroschisis cases, 774 (41%) with 2,368 associated anomalies (AA) and 814 of omphalocele, 727 (89%) with 4,092 AA. Typical AA profiles for Trisomy 18 (23% of omphalocele cases) and Beckwith-Wiedemann syndrome (15%) validated registry AA descriptors, chromosome disorders surprisingly accounting for 24% of known conditions with gastroschisis followed by expected amniotic band (ADAM) complex (23%) and amyoplasia/arthrogryposis (16%). Separation of known diagnoses, fetal-stillbirth cases, and transitional or secondary AA left 330 cases of gastroschisis with 594 AA (452 major, 142 minor) and 295 cases of omphalocele with 956 AA (683 major, 273 minor). Anomalies suggestive of vascular origin (intestinal atresias, amyoplasia, bands) were more frequent with gastroschisis and those of defective lateral folding (exstrophies, limb-body wall defects) with omphalocele. Most AA favoring omphalocele had parallel frequencies with gastroschisis, whether by system/region-for example, cardiac AA (10% of cases), contractures (4.7%), limb (3.7%), CNS (3.2%) for gastroschisis versus cardiac (35%), contractures (14%), digestive-excretory-trunk-axial (all ∼11%), CNS (9.9%) for omphalocele-or for particular minor/major AA-for example, micrognathia (0.72% versus 3.3%), spina bifida (0.59% versus 3.9%), anal atresia (0.73% versus 6.4%), two-vessel cord (0.22% versus 5.6%). Similar frequencies of many AA reflective of early patterning support common AWD origin within early developmental fields and reinforce the use of large birth defect numbers from suitably qualified registries to define anomaly mechanism as well as prevalence.

Isolated prenatal ultrasound findings predict the postnatal course in gastroschisis.

PURPOSE: The aim of the study was to identify which prenatal ultrasonographic findings in fetuses with gastroschisis correlate with complicated postnatal outcome. METHODS: Ultrasound findings at the 30th week of pregnancy and medical reports were statistically analyzed to identify independent prenatal ultrasonographic predictors of postnatal outcome. RESULTS: Completed prenatal data were gathered from 64 pregnancies. Prenatal intra-abdominal bowel dilatation (cutoff 10 mm) correlated with the presence of atresia (p < 0.01), longer administration of parenteral nutrition, extended hospital stay (median 53 vs. 21 days; 68 vs. 36 days, both p < 0.05), and greater number of additional surgical procedures (p < 0.05). Infants with antenatal presence of thickened bowel wall (greater than or equal to 3 mm) required longer administration of parenteral nutrition (median 34 vs. 20 days; p < 0.01) and prolonged stay (median 44 vs. 37 days; p < 0.05). Presence of oligohydramnion (amniotic fluid index below 8 cm) was connected with longer administration of parenteral nutrition in newborns (median 30 vs. 16 days; p < 0.05). CONCLUSION: The isolated presence of oligohydramnion with amniotic fluid index below 8 cm, thickened bowel wall equal to or more than 3 mm and the prenatal intra-abdominal dilatation with 10 mm cutoff had significant predictive value for the adverse postnatal outcome of patients with gastroschisis.

Sonographic predictors of postnatal bowel atresia in fetal gastroschisis.

OBJECTIVES: To estimate the association between antenatal bowel dilation and postnatal small-bowel atresia in fetal gastroschisis and to establish a threshold at which the risk of adverse neonatal outcome increases. METHODS: This was a retrospective cohort study of singleton gestations with an antenatal diagnosis of gastroschisis seen in our ultrasound unit from 2001 to 2010. We reviewed stored images from the last ultrasound examination before delivery, blinded to postnatal diagnoses and outcomes. Fetal intra- and extra-abdominal bowel dilation (IABD and EABD, respectively) and bowel-wall thickness were measured. Previously published definitions of bowel dilation, including > 6, > 10, > 14 and > 18 mm, were evaluated for association with the primary outcome of bowel atresia. The optimal threshold to define fetal bowel dilation was determined by evaluating the significance of association as well as test performance characteristics. RESULTS: Of 109 consecutive patients with fetal gastroschisis, there were four cases of intrauterine fetal demise and three neonatal deaths. Of the 94 live births with complete outcome data, 39 (41.5%) had measurable IABD. There were 14 (14.9%) cases of bowel atresia. Using a threshold of > 14 mm, IABD was significantly associated with an increased risk for bowel atresia (relative risk, 3.1 (95% CI, 1.2-8.2)) with a sensitivity of 57.1%, specificity of 75.0%, positive predictive value of 28.6% and negative predictive value of 90.9%. IABD > 14 mm was also associated with a significantly longer stay in neonatal intensive care unit. There was no significant association between EABD and bowel atresia at any of the thresholds evaluated. CONCLUSION: IABD > 14 mm is associated with an increased risk for postnatal bowel atresia in fetal gastroschisis. This finding may be useful in counseling patients regarding the anticipated postnatal course for their neonate.

Diagnosis of abdominal wall defects in the first trimester.

PURPOSE OF REVIEW: To review prognostic parameters reported recently in the evaluation of abdominal wall defects in the first trimester. RECENT FINDINGS: Evaluation of abdominal wall defects in the first trimester is based principally on associated structural or chromosomal anomalies. In the case of gastroschisis, which is rarely associated with other anomalies, evaluation of prenatal or postnatal outcome is based mainly on the course of pregnancy. In the case of isolated omphalocele in the first trimester, recent studies have evaluated parameters that could help predict prenatal or postnatal outcome. SUMMARY: We review recent studies using new parameters to diagnose abdominal wall defects in the first trimester and to provide early prenatal counselling to parents regarding prenatal and postnatal prognosis.

Postnatal outcome of fetuses with the prenatal diagnosis of gastroschisis.

OBJECTIVES: The purpose of this study was to assess the postnatal outcome and complications that arise in infants with the prenatal diagnosis of gastroschisis. METHODS: Prenatal sonograms with the diagnosis of gastroschisis were identified. Maternal age, indication for sonography, gestational age at diagnosis, other sonographic abnormalities, and postnatal outcome were recorded. RESULTS: Ninety-eight fetuses at 14.3 to 36 weeks' gestation had the diagnosis of gastroschisis on sonography. In 14 cases (14%), other fetal anomalies were identified, including hydronephrosis, hydrocephalus, coarctation of the aorta, and a limb anomaly. Bowel dilatation developed in 72 of 84 cases (86%) followed prenatally with sonography, and bowel wall thickening developed in 40 of 73 cases (55%). On postnatal follow-up, 57 of 68 infants (84%) had postnatal complications, many with multisystem complications, including 6 deaths, 40 with bowel-related complications, 30 with infectious complications, and 32 with anomalies involving other systems (genitourinary, cardiac, and central nervous system). The postnatal outcome did not correlate with the presence of bowel dilatation or bowel wall thickening on prenatal sonography. Only 11 infants (16.2%) had a completely uncomplicated postsurgical course. Hospital stays in survivors (n = 92) ranged from 8 to 307 days (mean, 53 days). CONCLUSIONS: Although reported survival rates are good for gastroschisis, the postoperative hospital stay is often lengthy, and complications are very common, especially those related to the gastrointestinal tract. Associated anomalies were more common in our study than previously reported.

Abdominal wall incision with or without exteriorization of bowel: results from a fetal lamb model for the embryogenesis of gastroschisis.

INTRODUCTION: The embryogenesis of gastroschisis is not completely understood. The aim of our study was to evaluate the impact of a simple abdominal wall defect versus a defect including eviscerated intestine or omentum for the development of gastroschisis in a fetal lamb model. MATERIAL AND METHODS: At mid-gestation (day 77) an abdominal wall defect was fetoscopically created with three different approaches in 19 German blackhead sheep. The intestine was eviscerated in 7 fetuses (group 1). The peritoneum was incised and a patch of the omentum pulled through the incision in 5 fetuses (group 2). In 7 fetuses (group 3) the skin and rectus muscle were incised until the peritoneum was visible. In this group, no abdominal contents were exteriorized and the peritoneum was left intact. A second fetoscopic procedure was performed 21 days later, assessing the condition and extension of eviscerated bowel. The fetus was retrieved by Cesarean section on day 132 and evaluated. RESULTS: The second fetoscopy acting as a control for the creation of gastroschisis demonstrated eviscerated and inflamed intestine in all 3 groups. The amount of eviscerated intestine did not appear to depend on the size of the defect nor on its duration. DISCUSSION: It appears that a simple incision of the abdominal wall with intact peritoneum is sufficient for the development of gastroschisis in a fetal sheep model. This finding may improve the understanding of the etiology of gastroschisis.

[Closing gastroschisis: a distinct entity with high morbidity and mortality]. / Closing Gastroschisis: eine Sonderform der Gastroschisis mit hoher Morbidität und Mortalität.

PURPOSE: We correlate severe bowel damage in gastroschisis to the rare intrauterine event of narrowing of the abdominal wall around the protruding intestines. We describe this "closing gastroschisis" as a distinct entity. Prenatal ultrasound findings as gastric or bowel dilation were compared to the postnatal findings in order to find markers for an early in utero diagnosis of closing gastroschisis. Early diagnosis could prompt timely delivery to save the compromised bowel and avoid short gut syndrome. MATERIALS AND METHODS: We documented the pre- and postnatal course of our patients with gastroschisis from 2007 to 2009.  Closing gastroschisis was suspected antenatally and confirmed postnatally. We identified 5 out of 18 patients showing closure of the abdominal wall with varying degrees of bowel damage. Prenatal ultrasound findings were correlated to the postnatally confirmed extent of intestinal damage. RESULTS: We could not find consistent ultrasound markers for prenatal diagnosis of closing gastroschisis. In prenatal ultrasound three patients presented significant gastric dilation and then experienced severe courses postnatally due to segmental gut necrosis. One of these three died and the other two developed short gut syndrome. In one case progressive intraabdominal loop dilation with simultaneous shrinking of the extraabdominal loops occurred corresponding to closing gastroschisis with segmental midgut necrosis. CONCLUSION: Closing gastroschisis must be seen as a special form of gastroschisis. Extended intestinal damage is often life-threatening. In longitudinal observation dynamics of fetal ultrasound findings can lead to the diagnosis of closing gastroschisis. Progressive intraabdominal loop dilation is always highly suspicious and must lead to close follow-up and timely delivery.

Umbilical artery pulsatility index and fetal abdominal circumference in isolated gastroschisis.

OBJECTIVES: To investigate changes in abdominal circumference (AC) and umbilical artery pulsatility index (UA-PI) with gestation in fetuses with isolated gastroschisis, and to determine whether a relationship exists between UA-PI and fetal AC. METHODS: Data from 58 pregnancies with isolated gastroschisis diagnosed at between 24 and 36 weeks' gestation were included in the study. Z-scores were calculated with respect to expected UA-PI values in normal pregnancies after log-transformation. AC-Z-scores were calculated with respect to expected size in normal pregnancies according to a standard chart. Functional linear discriminant analysis (FLDA) was applied to generate 50(th), 5(th) and 95(th) percentile curves for changes in both AC and UA-PI with gestational age in fetuses with gastroschisis. These curves were compared with the standard curves, as were the means. UA-PI was also plotted against AC. For this relationship, a robust Spearman correlation coefficient was obtained with FLDA. RESULTS: In fetuses with gastroschisis, there was a highly significant negative correlation between UA-PI and AC, normalized for gestation using Z-scores (median correlation coefficient, - 0.289; median P = 0.000023). Moreover, compared with standard curves AC was lower and UA-PI higher in the gestational-age range studied. Both the AC and UA-PI curves showed a significantly different rate of change with gestation compared with the normal ranges. The mean values for fetuses with gastroschisis compared with the standard AC and UA-PI range curves were significantly different for AC throughout gestation, and for UA-PI from 32 weeks' gestation. CONCLUSIONS: In fetal gastroschisis, it is well known that AC tends to be smaller, though UA-PI has not been reported to be abnormal in any consistent way. There is a clear relationship between the fetus's AC for gestation and UA-PI, which is not the case for normally grown fetuses. The data suggest that the growth restriction seen in gastroschisis may be explained by hypoxia, and not simply by the classical explanation of extra-abdominal displacement of the abdominal viscera.

The cholinergic response is increased in isolated ileum from gastroschisis rat model.

INTRODUCTION: Babies with gastroschisis (G) have high morbidity rate and long hospital stay due to bowel hypomotility caused by chronic exposure of the bowel to the amniotic fluid. Our aim was to evaluate the reactivity of isolated ileum in fetal rats selected for experimental gastroschisis. METHOD: G was surgically created at 18.5 days of gestation (term = 22 days). Concentration-dependent curve to the muscarinic agonist methacholine (1-30 µM) and contractions induced by electrical field stimulation (EFS, 1-16 Hz, 50 V, 1 ms) were carried out in isolated ileum of groups control (C), sham (S) and gastroschisis (G) (n = 30). Protein expression for M(3) was assessed by western blot analysis. RESULTS: The frequency and amplitude of spontaneous contractions were decreased in G (p < 0.001). Methacholine produced concentration-dependent contractions being the maximal response values higher in G (p < 0.01). EFS-induced frequency-dependent contractions showed 1.8 times higher in G as well as an increase of M(3) expression. CONCLUSION: The frequency and the amplitude of rhythmic contractions were reduced along with an increase in the contraction induced by mucarinic agonist and by EFS in G. These results suggest the occurrence of an adaptative supersensitivity to cholinergic response via increases in the protein expression for M(3) receptor.

Prenatal ultrasound in the prediction of bowel obstruction in infants with gastroschisis.

OBJECTIVE: To assess the value of prenatal ultrasound in predicting bowel obstruction requiring surgery in fetuses with prenatal diagnosis of gastroschisis. METHODS: The database of our center was searched for cases with an antenatal diagnosis of gastroschisis. The ultrasound images were reviewed blindly to assess the presence of intra- or extra-abdominal bowel dilatation. Details of surgical procedures were noted and the discharge letters were obtained. Pediatric follow-up was also obtained from pediatric surgeons, general practitioners or parents. RESULTS: In the 10-year period between November 1998 and September 2008 there were 62 cases with a prenatal diagnosis of gastroschisis. Postnatal outcome was not available for five cases, four pregnancies underwent termination and intrauterine fetal demise occurred in five cases. A final population of 48 liveborn infants was available for analysis. Intra-abdominal bowel dilatation was identified in 14 of these 48 fetuses (29.2%) and extra-abdominal bowel dilatation in 30 (62.5%) fetuses on prenatal ultrasound images. Eight fetuses (16.7%) had bowel obstruction. The relative risk of bowel obstruction with intra-abdominal bowel dilatation was 4.05 (95% CI, 1.12-14.70). On the other hand, the relative risk of bowel obstruction with extra-abdominal bowel dilatation was 1.0 (95% CI, 0.37-3.70). Four babies died, two of whom had intra- and one had extra-abdominal bowel dilatation. CONCLUSIONS: Intra-abdominal dilatation of the bowel on prenatal ultrasound examination appears to predict postnatal bowel obstruction and the need for surgical resection. Extra-abdominal bowel dilatation is observed frequently on prenatal ultrasound scans, but is not predictive of bowel obstruction.

Escape of the yolk sac: a hypothesis to explain the embryogenesis of gastroschisis.

Gastroschisis is a significant birth defect that in many countries has shown an increased prevalence in recent decades, and the change has affected primarily younger mothers. Despite numerous epidemiological studies no other consistent associated risk factor has been identified. In this paper we review the five main theories related to the pathogenesis of this malformation and outline the reasons why we think none fully explains the embryogenesis of gastroschisis. We briefly present some clinical observations we have made that we consider germane to the pathogenesis and outline a hypothesis that we think can account for the origins of this malformation. Our proposal is that the determining defect in gastroschisis is failure of the yolk sac and related vitelline structures to be incorporated into the umbilical stalk. Otherwise, ventral closure of the lateral abdominal walls occurs normally, thus orphaning the vitelline duct and yolk sac outside both the main body stalk and the abdominal wall. Thus, in addition to the umbilicus, the abdominal wall has a separate perforation through which the midpoint of the gut is attached to the exteriorized vitelline structures. This connection through the ventral wall prevents normal egress of the gut into the umbilical cord during the second month of development and acts as the egress point for the gut resulting in gastroschisis.

Is there a therapeutic role for fetoscopic surgery in the prenatal treatment of gastroschisis? A feasibility study in sheep.

BACKGROUND/PURPOSE: Gastroschisis is a malformation of the anterior abdominal wall that consists of a right paraumbilical defect with bowel loops bathed in the amniotic fluid. The prognosis relies mainly on morbidity attributable to intrauterine bowel loss or postpartum bowel dysfunction. The purpose of this study was to evaluate a potential role for fetoscopic surgery in severely affected fetuses with this condition. METHODS: Employing fetoscopy, we created a laparoschisis model in eight fetal sheep between 74-92 days of gestation; median 86.5 days). Twenty to 31 days after fetoscopic creation of fetal laparoschisis, a second procedure was scheduled in six survivors of the first surgery with the goal of assessing the potential for fetoscopic intervention in this condition. RESULTS: In the six survivors, macroscopic intestinal changes achieved by this animal model resembled those of human fetuses with gastroschisis. Whereas fetoscopic enlargement of the defect within the abdominal wall was feasible, in none of the fetuses was return of herniated abdominal viscera followed by abdominal closure possible using fetoscopic instrumentation. Furthermore, any attempt to return the herniated viscera into the fetal abdomen resulted in immediate and severe hemodynamic compromise of the fetoplacental circulation by stretching of the intra-abdominal umbilical arteries and vein. CONCLUSION: Minimally invasive fetoscopic enlargement of the defect within the abdominal wall is feasible in sheep fetuses with iatrogenic laparoschisis. This approach might benefit human fetuses with gastroschisis considered at high risk for bowel loss by constriction at the defect site. In contrast, return of herniated abdominal viscera followed by abdominal closure is limited by physiological constraints and seems currently not feasible with current fetoscopic instrumentation.

Gastroschisis associated with an intra-abdominal umbilical vein varix: a report of 2 cases.

We describe 2 cases of gastroschisis which were found to be associated with an intra-abdominal umbilical vein varix.

An evolutionary and developmental biology approach to gastroschisis.

Recent advances have now made it possible to speak of gastroschisis narrowly in morphogenetic terms invoking the Rittler-Beaudoin (R-B) model. This proceeds from the appreciation of gastroschisis as a congenital intestinal herniation (without cover or liver) within the primordial umbilical ring, mostly to the right side of a normally formed umbilical cord. Presently, it is unresolved whether this visceral prolapse represents failure of ring closure before return of the physiological hernia into the abdomen or rupture of the delicate amniotic/peritoneal membrane at the ring's edge to the right of the cord. Animal observations and experiments will be required to address this question effectively. If gastroschisis is, in fact, a primary malformation with the primordial umbilical ring as the developmental field involved, then homology implies potential gastroschisis in all amniotes with corresponding nourishment from yolk sac (aka omphalomesenteric) vessels going into the embryo and excretory products out via the ancient umbilical connection. It also implies homology of corresponding morphogenetic signal transduction cascades. We review the history of gastroschisis, its presumed pathogenesis, and the developmental biology of the amniotic umbilical ring from this perspective. Therefore, based on the animal and human evidence to date, we propose that gastroschisis is a primary midline malformation that involves the umbilical canal from amniotic to peritoneal space and its primordial umbilical ring, either through nonclosure or rupture of the membrane covering the area, mostly to the right, between the cord and the edge of the ring.