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

Embryology of the Abdominal Wall and Associated Malformations—A Review

In humans, the incidence of congenital defects of the intraembryonic celom and its associated structures has increased over recent decades. Surgical treatment of abdominal and diaphragmatic malformations resulting in congenital hernia requires deep knowledge of ventral body closure and the separation of the primary body cavities during embryogenesis. The correct development of both structures requires the coordinated and fine-tuned synergy of different anlagen, including a set of molecules governing those processes. They have mainly been investigated in a range of vertebrate species (e.g., mouse, birds, and fish), but studies of embryogenesis in humans are rather rare because samples are seldom available. Therefore, we have to deal with a large body of conflicting data concerning the formation of the abdominal wall and the etiology of diaphragmatic defects. This review summarizes the current state of knowledge and focuses on the histological and molecular events leading to the establishment of the abdominal and thoracic cavities in several vertebrate species. In chronological order, we start with the onset of gastrulation, continue with the establishment of the three-dimensional body shape, and end with the partition of body cavities. We also discuss well-known human etiologies.

Examining the Relationship Between Gastroschisis and Placental Fetal Vascular Malperfusion

INTRODUCTION

Gastroschisis is a congenital malformation characterized by intestinal herniation through an abdominal wall defect. Despite its unknown pathogenesis, known risk factors include maternal smoking, alcohol use, and young maternal age. Previous work has shown that gastroschisis is associated with placental delayed villous maturation, and the goal of this study was to assess for additional associated placental pathologies that may help clarify the pathogenesis of gastroschisis.

METHODS

We conducted a retrospective slide review of 29 placentas of neonates with gastroschisis. Additionally, we reviewed pathology reports from one control group of 30 placentas with other congenital malformations. Gross and histological data were collected based on a standardized rubric.

RESULTS

Gastroschisis was associated with increased placental fetal vascular malperfusion (FVM) in 62% of cases (versus 0% of controls, p < 0.0001). It was also associated with increased placental villous maldevelopment in 76% of cases (versus 3% of controls, p < 0.0001).

CONCLUSION

Our study demonstrates an association between gastroschisis and FVM. While FVM could be the consequence of vascular disruption due to the ventral location of gastroschisis, it could also reflect estrogen-induced thrombosis in early pregnancy. Further research is needed to separate these possibilities and determine the cause of the placental FVM observed in gastroschisis.

Gastroschisis: A State-of-the-Art Review

Gastroschisis, the most common type of abdominal wall defect, has seen a steady increase in its prevalence over the past several decades. It is identified, both prenatally and postnatally, by the location of the defect, most often to the right of a normally-inserted umbilical cord. It disproportionately affects young mothers, and appears to be associated with environmental factors. However, the contribution of genetic factors to the overall risk remains unknown. While approximately 10% of infants with gastroschisis have intestinal atresia, extraintestinal anomalies are rare. Prenatal ultrasound scans are useful for early diagnosis and identification of features that predict a high likelihood of associated bowel atresia. The timing and mode of delivery for mothers with fetuses with gastroschisis have been somewhat controversial, but there is no convincing evidence to support routine preterm delivery or elective cesarean section in the absence of obstetric indications. Postnatal surgical management is dictated by the condition of the bowel and the abdominal domain. The surgical options include either primary reduction and closure or staged reduction with placement of a silo followed by delayed closure. The overall prognosis for infants with gastroschisis, in terms of both survival as well as long-term outcomes, is excellent. However, the management and outcomes of a subset of infants with complex gastroschisis, especially those who develop short bowel syndrome (SBS), remains challenging. Future research should be directed towards identification of epidemiological factors contributing to its rising incidence, improvement in the management of SBS, and obstetric/fetal interventions to minimize intestinal damage.

Gastroschisis Is Associated With Placental Delayed Villous Maturation

Gastroschisis is a congenital abnormality characterized by visceral herniation through an abdominal wall defect. While the cause of gastroschisis is unknown, it has been linked to risk factors including young maternal age, smoking, and alcohol use during pregnancy. To date, the only established placental correlate is amniocyte vacuolization. Based on our clinical experience, we hypothesized that delayed villous maturation (DVM) is also associated with gastroschisis. We conducted a retrospective slide review of 23 placentas of neonates with gastroschisis. Additionally, we selected 2 control groups of placentas: 1 with a previous diagnosis of DVM and 1 with normal villous morphology. All placentas were randomized and reviewed by 2 perinatal pathologists, who were blinded to the group; DVM and amniocyte vacuolization were assessed. Gastroschisis was associated with increased placental DVM in 65.2% of cases (vs 13.6% of controls; P = .0007) and increased amniocyte vacuolization in 52.2% of cases (vs 9.1% of controls; P = .003) compared to the control group. Based on the normal and DVM groups, kappa agreement between current slide review and initial pathology diagnosis was 0.419, indicating moderate agreement. Our study shows that gastroschisis is associated with placental DVM. This association may be due to (1) a common upstream factor contributing to both gastroschisis and DVM or (2) DVM may be a consequence of the altered placental and amniotic environment in the context of gastroschisis.

Changes in the Prevalence of Embryologic Remnants in Umbilical Cord With Gestational Age

The aim of this study was to examine the prevalence of embryologic remnants in umbilical cords of different gestational ages. Sections from 392 umbilical cords were examined using light microscopy. Of these, 52% contained at least 1 remnant, most commonly of the allantoic duct type. Although there was a significant decrease in vitelline duct remnants over increasing gestational age, from 11% at weeks 11-25 to 1.6% at weeks 36-42 (P = .009; χ² test), the allantoic duct remnants remained constant in prevalence irrespective of gestational age.

Bioinformatic Analysis of Gene Variants from Gastroschisis Recurrence Identifies Multiple Novel Pathogenetic Pathways: Implication for the Closure of the Ventral Body Wall

We investigated whether likely pathogenic variants co-segregating with gastroschisis through a family-based approach using bioinformatic analyses were implicated in body wall closure. Gene Ontology (GO)/Panther functional enrichment and protein-protein interaction analysis by String identified several biological networks of highly connected genes in UGT1A3, UGT1A4, UGT1A5, UGT1A6, UGT1A7, UGT1A8, UGT1A9, UGT1A10, AOX1, NOTCH1, HIST1H2BB, RPS3, THBS1, ADCY9, and FGFR4. SVS–PhoRank identified a dominant model in OR10G4 (also as heterozygous de novo), ITIH3, PLEKHG4B, SLC9A3, ITGA2, AOX1, and ALPP, including a recessive model in UGT1A7, UGT1A6, PER2, PTPRD, and UGT1A3. A heterozygous compound model was observed in CDYL, KDM5A, RASGRP1, MYBPC2, PDE4DIP, F5, OBSCN, and UGT1A. These genes were implicated in pathogenetic pathways involving the following GO related categories: xenobiotic, regulation of metabolic process, regulation of cell adhesion, regulation of gene expression, inflammatory response, regulation of vascular development, keratinization, left-right symmetry, epigenetic, ubiquitination, and regulation of protein synthesis. Multiple background modifiers interacting with disease-relevant pathways may regulate gastroschisis susceptibility. Based in our findings and considering the plausibility of the biological pattern of mechanisms and gene network modeling, we suggest that the gastroschisis developmental process may be the consequence of several well-orchestrated biological and molecular mechanisms which could be interacting with gastroschisis predispositions within the first ten weeks of development.

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.

Prevalence and predictors of mortality in gastroschisis: a population-based study of 4803 cases in the USA

Purpose: Gastroschisis is a rare congenital anomaly consisting of an abdominal wall defect resulting in extrusion of the abnormal organs. Survival of these infants exceeds 90%. Few large-scale studies have examined the predictors of mortality for these infants. Our objective was to conduct a population-based study to determine prevalence and predictors of mortality among infants born with gastroschisis.Materials and methods: We used the "Period Linked Birth-Infant Death" database to create a cohort of all births occurring between 2009 and 2013. Infants were categorized by the presence of gastroschisis, excluding infants born at <24-week gestation. Baseline maternal and newborn characteristics were compared for infants who survived and those who died. Multivariate logistic regression models were used to estimate the effect of maternal and fetal factors on mortality, while adjusting for appropriate baseline characteristics.Results: There were 4803 cases of gastroschisis, with 287 deaths. The prevalence of gastroschisis increased from 2.04 to 2.49/10,000 births over the study period. The rate of death stayed constant at about 5.9%. We found that 38.1% of these infants died on day 0 of life. Statistically significant predictors of mortality were the presence of an additional congenital anomaly, birth weight <2500 g, prepregnancy diabetes, gestational age <34 weeks, paying out of pocket for healthcare, and maternal obesity.Conclusions: The prevalence of gastroschisis in the USA increased, yet the mortality rate remained stable. Infants born preterm <34 weeks, with birth weights <2500 g, or with an additional congenital anomaly were at the highest risk of death.

Insights into the etiology and embryology of gastroschisis

The development of gastroschisis has long remained an area of interest and controversy. Successive theories about its pathogenesis are herein reviewed and discussed. Two historical assumptions, that omphalocele results from a persistent umbilical hernia, and that gastroschisis does not involve the umbilical cord, are dismissed. Therefore, one can envision gastroschisis for what it is, i.e. a ruptured physiological hernia. The causal agents for this intrauterine accident to occur are yet to be determined. Further bowel damage and complications can be explained by the mesenteric insult.

Gastroschisis. Case report and management in primary care services

Introducción. La gastrosquisis es una enfermedad de baja prevalencia, pero de muy buen pronóstico si se realiza un adecuado manejo inicial. El presente escrito tiene como objetivo realizar una descripción de esta patología, destacando la importancia de su correcto manejo en el primer nivel.Presentación del caso. Neonato a término con hallazgo de gastrosquisis en primer nivel quien fue remitido al servicio de neonatología de una institución de tercer nivel. El infante recibió manejo interdisciplinario y cierre quirúrgico gradual y tuvo evolución favorable tras 3 meses de hospitalización.Discusión. No existe claridad sobre la causa exacta de la gastrosquisis, ya que es una enfermedad multifactorial. Su diagnóstico puede realizarse desde la etapa prenatal mediante la ultrasonografía, un método que posee alta sensibilidad y especificidad para su detección.Conclusión. La gastrosquisis es una enfermedad que para su diagnóstico y tratamiento requiere de personal especializado en primer nivel, lo que garantiza un correcto manejo inicial y evita futuras complicaciones.

A novel approach in the treatment of neonatal gastroschisis: a review of the literature and a single-center experience

Gastroschisis is a congenital abdominal wall defect and its management remains an issue. We performed a review of the literature to summarize its evaluation, management and outcome and we describe a new type of surgical reduction performed in our center without anesthesia (GA), immediately after birth, in the delivery room. Between January 2002 and March 2013, we enrolled all live born infants with gastroschisis referred to the third-level Division of Obstetrics and Gynecology "San Camillo" of Rome. Two groups of infants were identified: group 1 in which gastroschis reduction was performed by the traditional technique and group 2 in which reduction was immediately performed after birth in the delivery room without GA. Twelve infants were enrolled in group 1, and seven infants in group 2. Statistical significance was observed between the groups regarding the hospital stay, for the duration of parenteral nutrition and full oral feeds (p = .004). Survival was similar between two groups. The reduction without GA performed immediately after birth in a delivery room encourages the relationship between the mother and her child and appears to be a safe and feasible technique in a selected group of patients with simple gastroschisis defect; for this reason, it could represent a valid alternative to traditional approach.

Vitelline duct pathologies in neonates

OBJECTIVE

The aim of this study was to review the management of pediatric cases of vitelline duct pathology (VDP) detected surgically or incidentally during the neonatal period and the outcomes.

METHODS

The data of newborns who were symptomatic and underwent VDP resection or who were incidentally diagnosed with VDP at a single institution between 1985 and 2015 were retrospectively analyzed in terms of age, sex, clinical features, treatment, perioperative findings, ectopic tissue pathology, and postoperative follow-up information.

RESULTS

Among the 36 newborns enrolled in this study, 26 were male and 10 were female (2.6:1). The median weight was 2400 g (range: 800-3090 g). In 16 cases (14 males and 2 females; 7:1) the VDP was surgically repaired. Pathological evaluation indicated that 43% (n=7) of the cases had ectopic gastric mucosa. VDP was incidentally discovered in 12 males and 8 females (1.5:1). VDP was removed in 10 cases (50%) and left intact in others. Ectopic gastric mucosa was observed in 10% of the VDP removal cases. Ectopic gastric tissue was more prevalent in the surgical VDP cases than in the incidentally discovered and VDP removal cases (p<0.05). Male predominance was greater in the surgically repaired cases than in the incidentally discovered cases (p<0.05). One patient whose VDP was discovered incidentally was admitted 3 years later with obstruction due to intussusception caused by Meckel's diverticulum, and 1 patient was admitted with rectal bleeding at 11 years of age.

CONCLUSION

Symptomatic VDP in the newborn demonstrates a significant gender difference. Symptomatic cases are more likely to have ectopic gastric tissue than non-symptomatic cases. Incidentally detected cases without removal should be followed closely for future complications.

Maternal Antibodies to Herpes Virus Antigens and Risk of Gastroschisis in Offspring

Gastroschisis risk is highest in offspring of young women and is increasing in prevalence, suggesting that exposures that are increasingly common among younger females may be causal. Some infections by viruses in the herpes family are more common in the earlier childbearing years and have been increasing in prevalence over time. Data from the Finnish Maternity Cohort were linked to Finnish malformation and birth registers (1987-2012) for this study, a nested case-control study of mothers of offspring with gastroschisis and age-matched controls. Maternal antibody responses in early pregnancy (mean gestational age = 11.1 weeks) to Epstein Barr virus (EBV), herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), and cytomegalovirus were measured. Conditional logistic regression models were used to estimate odds ratios (and 95% confidence intervals) for high immunoglobulin reactivity. Odds ratios for high immunoglobulin M (IgM) reactivity to EBV-viral capsid antigen and HSV-1 or HSV-2 (as indicators of recent infection) were 2.16 (95% confidence interval (CI): 0.97, 4.79) and 1.94 (95% CI: 0.74, 5.12), respectively. For higher immunoglobulin G (IgG) reactivity to EBV-viral capsid antigen and HSV-2 IgG, odds ratios were 2.16 (95% CI: 0.82, 5.70) and 2.48 (95% CI: 1.50, 4.10), respectively. Reactivities to HSV-1 IgG, cytomegalovirus IgM, or cytomegalovirus IgG did not appear to increase gastroschisis risk. Primary EBV infection was not associated with gastroschisis, but observed associations with both IgM and IgG reactivities to EBV and HSV suggest that reactivations may be risk factors for it.

Gastroschisis and maternal intake of phytoestrogens

The prevalence of gastroschisis has increased significantly in the past few decades. The strongest risks have been observed for women <25 years old or of low body mass index, and maternal diet also been proposed to be associated with risk. The objective of this study was to evaluate whether the risk of gastroschisis is associated with maternal dietary intake of phytoestrogens. The analysis includes data on mothers of 409 gastroschisis cases and 3,007 controls who delivered their infants from 2005 to 2010 and participated in the National Birth Defects Prevention Study, a multistate, population-based, case-control study. Detailed information was obtained from maternal telephone interviews that included a validated food frequency questionnaire. We conducted logistic regression analyses that included each phytoestrogen in its continuous form (to test for linearity) and quadratic form (to test for non-linearity), adjusted for maternal energy intake, age, BMI, race-ethnicity, and smoking in 1st trimester. Logistic regression analysis indicated that biochanin A, formonoetin, and coumestrol had a significant non-linear association with gastroschisis (P-value <0.05 for quadratic term). Lower intakes were associated with increased risk, with somewhat stronger but relatively modest associations at the lower end of the distribution; for example, the ORs for the 10th versus 50th percentiles ranged from 1.1 to 1.2. Associations were not significant for the other phytoestrogens. This study provides some evidence for association with certain phytoestrogens, after adjusting for covariates. The implications of our findings for clinical practice are uncertain pending other studies examining this association. © 2016 Wiley Periodicals, Inc.

When Closure Fails: What the Radiologist Needs to Know About the Embryology, Anatomy, and Prenatal Imaging of Ventral Body Wall Defects

Ventral body wall defects (VBWDs) are one of the main categories of human congenital malformations, representing a wide and heterogeneous group of defects sharing a common feature, that is, herniation of one or more viscera through a defect in the anterior body wall. Gastroschisis and omphalocele are the 2 most common congenital VBWDs. Other uncommon anomalies include ectopia cordis and pentalogy of Cantrell, limb-body wall complex, and bladder and cloacal exstrophy. Although VBWDs are associated with multiple abnormalities with distinct embryological origins and that may affect virtually any system organs, at least in relation to anterior body wall defects, they are thought (except for omphalocele) to share a common embryologic mechanism, that is, a failure involving the lateral body wall folds responsible for closing the thoracic, abdominal, and pelvic portions of the ventral body wall during the fourth week of development. Additionally, many of the principles of diagnosis and management are similar for these conditions. Fetal ultrasound (US) in prenatal care allows the diagnosis of most of such defects with subsequent opportunities for parental counseling and optimal perinatal management. Fetal magnetic resonance imaging may be an adjunct to US, providing global and detailed anatomical information, assessing the extent of defects, and also helping to confirm the diagnosis in equivocal cases. Prenatal imaging features of VBWDs may be complex and challenging, often requiring from the radiologist a high level of suspicion and familiarity with the imaging patterns. Because an appropriate management is dependent on an accurate diagnosis and assessment of defects, radiologists should be able to recognize and distinguish between the different VBWDs and their associated anomalies. In this article, we review the relevant embryology of VBWDs to facilitate understanding of the pathologic anatomy and diagnostic imaging approach. Features will be illustrated with prenatal US and magnetic resonance imaging and correlated with postnatal and clinical imaging.

Abdominal wall defects: prenatal diagnosis, newborn management, and long-term outcomes

Omphalocele and gastroschisis represent the most frequent congenital abdominal wall defects a pediatric surgeon is called to treat. There has been an increased reported incidence in the past 10 years mainly due to the diffuse use of prenatal ultrasound. The early detection of these malformations, and related associated anomalies, allows a multidisciplinary counseling and planning of delivery in a center equipped with high-risk pregnancy assistance, pediatric surgery, and neonatology. At present times, closure of defects, even in multiple stages, is always possible as well as management of most of cardiac-, urinary-, and gastrointestinal-associated malformations. The progress, herein discussed, in the care of newborns with abdominal wall defects assures most of them survive and reach adulthood. Some aspects of transition of medical care will also be considered, including fertility and cosmesis.

Complex gastroschisis is a different entity to simple gastroschisis affecting morbidity and mortality-a systematic review and meta-analysis

BACKGROUND

Comparison of the outcome of newborns with simple (sGS) and complex gastroschisis (cGS: gastroschisis with atresia, necrosis, perforation or volvulus).

MATERIALS AND METHODS

We conducted a systematic database search, quality assessment and meta-analyzed relevant articles which evaluated the mortality and morbidity of newborns with cGS versus sGS. Risk ratios (RR) with 95% confidence interval (CI) were reported for categorical data, and the mean difference (MD) was calculated for continuous data. Pooled estimates of RR and MD were computed using generic inverse variance and a random-effects model.

RESULTS

Of 19 identified reports, 13 eligible studies were included. The mortality of infants with cGS (16.67%) was significantly higher than sGS (2.18%, RR: 5.39 [2.42, 12.01], p<0.0001). Significantly different outcome was found for the following parameters: Infants with cGS are started on enteral feedings later and they take longer to full enteral feedings with a subsequent longer duration of parenteral nutrition. Their risk of sepsis, short bowel syndrome and necrotizing enterocolitis is higher. They stay longer in hospital and are more likely to be sent home with enteral tube feedings and parenteral nutrition.

DISCUSSION

Occurring in 17% of infants born with gastroschisis, complex gastroschisis is associated with a significantly increased morbidity and mortality. More research should be focused on this special subgroup of patients, not only on postnatal management, but additionally directing efforts to improve diagnosing and predicting complex gastroschisis prenatally as well as implement any probable fetal intervention to alleviate its disastrous outcome.

Dermatan sulfate epimerase 1 deficient mice as a model for human abdominal wall defects

BACKGROUND

Dermatan sulfate (DS) is a highly sulfated polysaccharide with a variety of biological functions in extracellular matrix organization and processes such as tumorigenesis and wound healing. A distinct feature of DS is the presence of iduronic acid, produced by the two enzymes, DS-epimerase 1 and 2, which are encoded by Dse and Dsel, respectively.

METHODS

We have previously shown that Dse knockout (KO) mice in a mixed C57BL/6-129/SvJ background have an altered collagen matrix structure in skin. In the current work we studied Dse KO mice in a pure NFR genetic background.

RESULTS

Dse KO embryos and newborns had kinked tails and histological staining revealed significantly thicker epidermal layers in Dse KO mice when compared with heterozygote (Het) or wild-type (WT) littermates. Immunochemical analysis of the epidermal layers in newborn pups showed increased expression of keratin 5 in the basal layer and keratin 1 in the spinous layer. In addition, we observed an abdominal wall defect with herniated intestines in 16% of the Dse KO embryos. Other, less frequent, developmental defects were exencephaly and spina bifida.

CONCLUSION

We conclude that the combination of defective collagen structure in the dermis and imbalanced keratinocyte maturation could be responsible for the observed developmental defects in Dse KO mice. In addition, we propose that Dse KO mice could be used as a model in pathogenetic studies of human fetal abdominal wall defects.

Early pregnancy agricultural pesticide exposures and risk of gastroschisis among offspring in the San Joaquin Valley of California

BACKGROUND

Prevalence of gastroschisis has inexplicably been increasing over the past few decades. Our intent was to explore whether early gestational exposures to pesticides were associated with risk of gastroschisis.

METHODS

We used population-based data, accompanied by detailed information from maternal interviews as well as information on residential proximity to a large number of commercial pesticide applications during early pregnancy. The study population derived from the San Joaquin Valley of California (). Cases were 156 infants/fetuses with gastroschisis and controls were 785 infants without birth defects.

RESULTS

Among 22 chemical pesticide groups analyzed, none had an elevated odds ratio with an associated confidence interval that excluded 1.0, although exposure to the triazine group showed borderline significance. Among 36 specific pesticide chemicals analyzed, only exposure to petroleum distillates was associated with an elevated risk, odds ratio = 2.5 (1.1-5.6). In general, a substantially different inference was not derived when analyses were stratified by maternal age or when risk estimation included adjustment for race/ethnicity, body mass index, folic acid supplement use, and smoking.

CONCLUSION

Our study rigorously adds to the scant literature on this topic. Our a priori expectation was that we would observe certain pesticide compounds to be particularly associated with young age owing to the disproportionate risk observed for young women to have offspring with gastroschisis. We did not observe an exposure profile unique to young women.

A vascular and thrombotic model of gastroschisis

A binary vascular/thrombotic pathogenesis for gastroschisis, a form of congenital bowel herniation, is proposed, where normal right umbilical vein involution creates a possible site for thrombosis adjacent to the umbilical ring. If thrombosis occurs, it weakens the area, explaining overwhelmingly right-sided lesions. The model arises from the existence of two groups of risk factors with different maternal age associations. Older mothers show a greater association with vascular factors (although this may actually represent a lack of any significant maternal age effect), consistent with associations of gastroschisis with congenital heart lesions and with amyoplasia. Alternatively, other predispositions, and especially decreased maternal age, the greatest known risk factor, associate with factors raising maternal estrogen, with evidence that estrogen in turn acts here as a predisposition to thrombosis. Absorption of thrombotic by-products from the amniotic fluid can explain the unusual amniocyte inclusions that are common with gastroschisis, while a role for estrogens suggests a connection between rising gastroschisis prevalence and increasing environmental contamination with estrogen disruptors. This model explains a variety of structural and epidemiological findings, and suggests that stratification of data based on binary effects may clarify associated risks and mechanisms. The model also shows that what is often referred to as vascular disruption may actually reflect alternative or additional factors instead, including thrombosis as a primary mechanism.

Gastroschisis with ceco-appendicular agenesis: a novel presentation

Gastroschisis is associated with intestinal atresia and malrotation. A few cases have been reported of appendicular agenesis associated with gastroschisis. No previous case has been reported of cecal agenesis with gastroschisis in the literature. As cecal agenesis is a very rare anomaly, its concomitant presentation with gastroschisis is extremely rare. We report a case of gastroschisis associated with ceco-appendicular agenesis. The possible embryological explanation for the presentation is discussed.

Development of the rectus abdominis and its sheath in the human fetus

PURPOSE

Although the rectus abdominis and its sheath are well known structures, their development in the human fetus is poorly understood.

MATERIALS AND METHODS

We examined rectus abdominis and sheath development in semiserial horizontal sections of 18 fetuses at 5-9 weeks of gestation.

RESULTS

Rectus muscle differentiation was found to commence above the umbilicus at 6 weeks and extend inferiorly. Until closure of the anterior chest wall via fusion of the bilateral sternal anlagen (at 7 weeks), the anterior rectal sheath originated from the external oblique and developed towards the medial margin of the rectus abdominis at all levels, including the supracostal part. After formation of the anterior sheath, fascial laminae from the internal oblique and transversus abdominis contributed to formation of the posterior rectus sheath. However, the posterior sheath was absent along the supracostal part of the rectus abdominis, as the transversus muscle fibers reached the sternum or the midline area. Therefore, it appeared that resolution of the physiological umbilical hernia (8-9 weeks) as well as chest wall closure was not required for development of the rectus abdominis and its sheath. Conversely, in the inferior part of the two largest fetal specimens, after resolution of the hernia, the posterior sheath underwent secondary disappearance, possibly due to changes in mechanical stress.

CONCLUSION

Upward extension of the rectus abdominis suddenly stopped at the margin of the inferiorly developing pectoralis major without facing the external intercostalis. The rectus thoracis, if present, might correspond to the pectoralis.

Histology of a paraumbilical band in a neonate with gastroschisis

We report a case of gastroschisis in which a paraumbilical band was found at the right margin of the abdominal wall defect and extended into the antimesenteric side of the small intestine. The band consisted of 2 thin cords. Microscopically, 1 band showed a fibrous tissue, and the other 1 revealed a unique vascular structure resembling the vitelline artery and vein, suggesting that the paraumbilical band represents a remnant of the yolk stalk that failed to be incorporated into the umbilical stalk. The origin of the paraumbilical band and an associated pathogenetic hypothesis of gastroschisis are discussed.

Neonatal abdominal wall defects

Gastroschisis and omphalocele are the two most common congenital abdominal wall defects. Both are frequently detected prenatally due to routine maternal serum screening and fetal ultrasound. Prenatal diagnosis may influence timing, mode and location of delivery. Prognosis for gastroschisis is primarily determined by the degree of bowel injury, whereas prognosis for omphalocele is related to the number and severity of associated anomalies. The surgical management of both conditions consists of closure of the abdominal wall defect, while minimizing the risk of injury to the abdominal viscera either through direct trauma or due to increased intra-abdominal pressure. Options include primary closure or a variety of staged approaches. Long-term outcome is favorable in most cases; however, significant associated anomalies (in the case of omphalocele) or intestinal dysfunction (in the case of gastroschisis) may result in morbidity and mortality.

Associations between periconceptional alcohol consumption and craniosynostosis, omphalocele, and gastroschisis

BACKGROUND

Alcohol consumption during pregnancy is known to be associated with certain birth defects, but the risk of other birth defects is less certain. The authors examined associations between maternal alcohol consumption during pregnancy and craniosynostosis, omphalocele, and gastroschisis among participants in the National Birth Defects Prevention Study, a large, multicenter case-control study.

METHODS

A total of 6622 control infants and 1768 infants with birth defects delivered from 1997-2005 were included in the present analysis. Maternal alcohol consumption was assessed as any periconceptional consumption (1 month prepregnancy through the third pregnancy month), and by quantity-frequency, duration, and beverage type. Alcohol consumption throughout pregnancy was explored for craniosynostosis since the period of development may extend beyond the first trimester. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression analysis. OR were adjusted for age, race/ethnicity, and state of residence at time of infant's birth. Gastroschisis OR were also adjusted for periconceptional smoking.

RESULTS

Periconceptional alcohol consumption and craniosynostosis showed little evidence of an association (OR = 0.92; CI: 0.78-1.08), but alcohol consumption in the second (OR = 0.65; CI: 0.47-0.92) and third trimesters (OR = 0.68; CI: 0.49-0.95) was inversely associated with craniosynostosis. Periconceptional alcohol consumption was associated with omphalocele (OR = 1.50; CI: 1.15-1.96) and gastroschisis (OR = 1.40; CI: 1.17-1.67).

CONCLUSIONS

Results suggest that maternal periconceptional alcohol consumption is associated with omphalocele and gastroschisis, and second and third trimester alcohol consumption are inversely associated with craniosynostosis.

Development of gastroschisis as seen by magnetic resonance imaging

OBJECTIVES

To describe the magnetic resonance imaging (MRI) morphology and fetal development of gastroschisis.

METHODS

Twenty-seven fetal MRI studies of 24 fetuses (mean gestational age 30 (range, 21-38) weeks), with gastroschisis were retrospectively analyzed. The extra- and intra-abdominal positions of the abdominal organs were assessed on T1- and T2-weighted and steady-state free-precession sequences with emphasis on the intra-abdominal findings.

RESULTS

Third-trimester fetuses (n = 16) showed a uniform morphology: the extracorporeal bowel included jejunum, ileum and colon except for parts of the sigmoid and the rectum. Intra-abdominally the stomach was in contact with the left-sided urinary bladder in 15 of these. Second-trimester fetuses (n = 8) differed with respect to the amount of intra-abdominal bowel and had longer sections of the colon and jejunum intra-abdominally. Intrauterine follow-up (n = 3) demonstrated exteriorization of these bowel segments. Three third-trimester fetuses with gastroschisis complicated by small bowel obstruction, in addition to the dilated small bowel loops, had variable lengths of intra-abdominal colon.

CONCLUSIONS

Fetal development of gastroschisis is a dynamic process lasting until birth. The typical morphology of gastroschisis changes from the second to the third trimester, since intra-abdominal bowel becomes eventrated by the end of the second trimester. This process of eventration is stopped in cases of intestinal stenosis/atresia caused by narrowing of the abdominal wall defect, resulting in different lengths of intra-abdominal bowel. The time when this occurs may correlate with the amount of viable bowel in cases of intestinal atresia. The concept presented here explains the findings in closing gastroschisis.

Assessing the trend of gastroschisis prevalence in China from 1996 to 2007 using two analytical methods

BACKGROUND

In recent years, the prevalence of gastroschisis has increased remarkably in some areas and remained unchanged in other areas; however, in general, there is a recent increasing trend compared to the 1970s and 1980s. In this study, we explored the time trend of gastroschisis prevalence in China during 1996 to 2007.

METHODS

Data were retrieved from the hospital-based national monitoring database maintained by the Chinese Birth Defects Monitoring Network (CBDMN). The monitored subjects were infants born on the 28th gestational week or later, including live births and stillbirths. The maximal time for the diagnosis of a congenital malformation was the seventh day after birth. The secular trends on the overall prevalence and the different feature-specific prevalence of gastroschisis in China were analyzed using the linear chi-square test and the Poisson regression model.

RESULTS

The overall prevalence of gastroschisis in China was 2.54 per 10,000 births during 1996 to 2007. Except for the prevalence of gastroschisis that significantly increased among infants whose mothers were 20 to 24 years old (p=0.0498 for the linear chi-square test, p=0.0032 for the Poisson regression model analysis) and significantly decreased among infants whose mothers were 30 to 34 years old (p=0.0177 for the Poisson regression model analysis), no significant changes were found in the overall and remaining feature-specific prevalences.

CONCLUSION

The overall prevalence of gastroschisis in China did not change remarkably during 1996 to 2007; but the prevalence of gastroschisis significantly increased among infants whose mothers were 20 to 24 years old and decreased among infants whose mothers were 30 to 34 years old.

Perinatal demography of gastroschisis in North Queensland

AIM

To review the demography of gastroschisis in North Queensland.

METHODS

A retrospective chart review of live born cases of gastroschisis originating in North Queensland from 1988 to 2007.

RESULTS

Fifty-nine cases were identified, giving an overall rate of 3.2 per 10,000 live births. In mothers <20 years old compared with 20-24 and 25-29 it was 12.1, 6.3 and 1.7. Overall, the rate was higher in Indigenous mothers (6.6 vs. 2.6, OR 2.5; 95% CI 1.4-4.5, P= 0.0018). Overall, the rate increased significantly from 0.7 per 10,000 live births in the first 5 years of the study to 4.8 in the last (trend test P= 0.0015), but it increased particularly in mothers <20 years old, from 2.40 in the first 5 years to 19.3 in the last (trend test P= 0.0177). It also rose from 0 to 3.6 in those aged 25-29 (P= 0.0337) but remained stable in other age groups. There was no difference in the outcomes of babies born to Indigenous or non-Indigenous mothers, or in outcomes of babies delivered vaginally or by Caesarean section, or in outcomes of babies from any particular location in North Queensland. There was no significant difference in the average age of Indigenous and non-Indigenous mothers.

CONCLUSION

Gastroschisis is increasing in North Queensland, especially in mothers <20. Overall, the rate in Indigenous mothers is two to three times higher.

Pathogenic implications of remnant vitelline structures in gastroschisis

PURPOSE

The pathogenesis of gastroschisis is unknown. It may be helpful in understanding its pathogenesis to know the structural relationships among umbilical components including umbilical vessels, urachus, and vitelline structures, and thus, the authors investigated the remnants of vitelline structures in a series of cases of gastroschisis.

METHODS

Medical records of 41 cases with gastroschisis treated in our institute from 1979 to 2009 were retrospectively reviewed.

RESULTS

Paraumbilical bands, possible remnants of vitelline structures, were observed in 4 cases (9.8%). All 4 bands were attached to the skin edge of the abdominal defect without incorporation into the umbilical cord. The band ended at the mesentery in 3 cases and at the antimesenteric site of the ileum in the remaining case. Histologic findings showed fibrous tissues in all cases. One was possibly associated with the development of colonic atresia. Another was noticed after silo reduction when herniated bowels became strangulated by the band. The other 2 cases were uncomplicated.

CONCLUSIONS

Our findings may support the recently proposed hypothesis that the developmental failure of the yolk sac and related vitelline structures to merge with or to be incorporated into the umbilical stalk might be associated with the pathogenesis of the abdominal wall defect in gastroschisis. Paraumbilical bands derived from vitelline structures may possibly cause intestinal ischemia prenatally or postnatally.

The embryologic origin of ventral body wall defects

Ventral body wall defects include ectopia cordis, bladder exstrophy, and the abdominal wall malformations gastroschisis and omphalocele. The etiology of ectopia cordis, gastroschisis, and bladder exstrophy is not known, but they may be linked to abnormalities in the lateral body wall folds responsible for closing the thoracic, abdominal, and pelvic portions of the ventral body wall. These folds form in the fourth week (postfertilization) of development as a combination of the parietal layer of lateral plate mesoderm and overlying ectoderm and must move ventrally to meet in the midline. There are differential rates of cell proliferation in the folds and asymmetries in their movement that may be involved in teratogenic effects of toxic factors. Also, the fusion process between the folds is complex, involving cell-to-cell adhesion, cell migration, and cell reorganization and all of these phenomena may be targets for disruption, leading to malformations. In this regard, closure of the ventral body wall is likened to neural tube closure and involves similar processes. It also encompasses a similar time frame during development, such that most neural tube and ventral body wall defects have their origins during the fourth week of development. Omphalocele is a separate entity whose etiology is known. This defect is attributed to a failure of gut loops to return to the body cavity after their normal physiological herniation into the umbilical cord from the 6th to 10th week of development. Thus, the origin of this defect is completely different from that of the ventral body wall malformations.