Fetal abdominal wall defects – gastroschisis. Case presentation

Introduction

Gastroschisis is one of the most common congenital abdominal wall defects (AWD) in newborns. The prevalence is related to be 2-3 per 10000 births.

The risk factors associated with gastroschisis are maternal smoking, illicit drug use, alcohol consumption, environmental factors, socioeconomic status, young maternal age, and others⁽¹⁴⁾.

Classification

Gastroschisis can be classified as simple (no complication at all) or complex.

Complex gastroschisis may be defined by the presence of intestinal complications, such as atresia, perforation or necrosis.

Complex gastroschisis is related to be around 11-28% of cases, and it is usually associated with increased morbidity and mortality that lower the survival rate from more than 90% to 70-80% in developed countries.

The complications that might occur with gastroschisis during pregnancy are:

• Closing gastroschisis (rare) or complete closure of abdominal wall at birth, with the result of secondary atresia.
• The presence of only rudimentary herniated viscera or the complete loss of herniated bowel (vanishing gastroschisis).
• Inflammation of the bowel that becomes coated with inflammatory fibrotic peel due to exposure to amniotic fluid, with the result of thickening of bowel wall, decrease of motility, and potential luminal obstruction⁽¹³⁾.
• Much of the damage is due to the constriction, and usually this happens late in gestation.

Due to the aforementioned complications, it is crucial to detect signs of abdominal wall defects in utero. Gastroschisis is also associated with intestinal non-rotation.

Embryology

Initially the embryo is a flat disk-shaped structure without any body cavities and with an umbilical stalk attached anteriorly. By three weeks of gestation, the embryo consists of three layers: ectoderm, mesoderm and endoderm. At this age of gestation, the embryo will have lateral, cephalic and caudal edge folding⁽⁶⁾. The lateral folds give rise to the abdominal wall.

Failure of the lateral folds to fuse in the midline results in the development of an omphalocele. Cephalic fold is a precursor of the diaphragm, and it also is responsible for the migration of the heart into the chest. Defects of the cephalic folds result in the pentalogy of Cantrell (POC).

The caudal fold contains precursors of the intestinal, urinary and genital tracts in the form of the cloaca. A ventral diverticulum, the allantois, projects from the cloaca into the connecting umbilical stalk (also known as the body stalk), which attaches to the chorionic mesoderm, giving rise to the umbilical cord.

Between the fourth and the fifth weeks of gestation, the gastrointestinal tract develops as a continuous single-tube structure that lies within the embryo.

At approximately six weeks of gestational age (GA), after other organs have formed, the midgut migrates through the base of the umbilical stalk, known as the umbilical coelom (physiologic gut herniation).

After migration into umbilical coelom, the midgut undergoes rapid growth and elongation and partial rotation, which could not occur in the limited space of the abdominal cavity.

By the 11^th and 12^th weeks of gestational age, after completing its growth and 270-degree rotation within in the umbilical coelom, the midgut returns to the peritoneal cavity, where it undergoes final rotation and fixation. Failure of the development of the umbilical coelom results in the protrusion of intestines through the abdominal wall and the development of gastroschisis.

The exact causes of fetal ventral AWDs – including ectopia cordis, gastroschisis and bladder exstrophy – are unknown.

However, the cause is thought to be the abnormal development of the lateral body folds which is responsible for the closing of the thoracic, abdominal and pelvic portions of the ventral body wall⁽⁸⁾.

This is different from the cause of omphalocele which is the failure of return of the midgut loops into the body cavity after the physiologic herniation into the base of umbilical cord between four and eight weeks of gestational age⁽⁶⁾.

Diagnosis of abdominal wall defects in the first trimester

Typically, the diagnosis of AWD is done at the first-trimester screening for aneuploidies and anatomy scan by ultrasound. Attention should be paid to the confusion between omphalocele and gastroschisis.

It is important for the diagnosis to be accurate, as the management differs between entities. The distinction sometimes may be difficult in cases of in utero rupture of omphalocele sac. The elevation of AFP in the maternal serum is more likely to be observed in gastroschisis compared with omphalocele.

Amniotic fluid from gastroschisis fetuses contains elevated levels of proinflammatory cytokine interleukin-8 compared with controls⁽¹⁾.

Other factors that can damage the bowel are meconium in the amniotic fluid, amniotic beta endorphin, and the pH of amniotic fluid^(2-5).

After in utero diagnosis of AWD, the care of a pregnant woman should be transferred to a tertiary care center for further counseling and treatment by an interdisciplinary team, encompassing obstetricians, neonatologists and pediatric surgeons.

During pregnancy, serial ultrasounds are performed to evaluate different intestinal outcome parameters (including intestinal loops dilatation and bowel wall thickening, the amniotic fluid and growth of the fetus). Dilatation of the intraabdominal (not extra) bowel, as well as the presence of polyhydramnios are typically observed in complex gastroschisis.

A sudden decrease in fetal bowel diameter can indicate bowel perforation. The role of ultrasound in gastroschisis is to monitor fetal growth, to identify fetal early distress, predict complication, and allow that the delivery occur in a specialized center to improve neonatal outcome.

The fetal growth in case of gastroschisis may be underestimated due to the extruded intraabdominal content. Gastroschisis in not lethal usually, but the evisceration of bowel is the subject of more investigations and management guidelines.

The fetus can be delivered by caesarean section or vaginal delivery under controlled conditions at about 36 weeks of gestational age. In the USA, Brebner et al.⁽¹⁵⁾ reported that, although the prevalence of gastroschisis is increasing, the mortality rate remained the same. They indicated that, with appropriate care, the survival rate is 90%, and infants with greater risk are those born with less than 2500 g or before 34 weeks of gestational age.

According to recent data, spontaneous labor associated with adverse outcome and ongoing exposure of bowel to amniotic fluid may result in bowel injury and premature labor.

Elective delivery occurs between 35 and 36 weeks of gestational age to reduce the post-delivery morbidity.

Novel therapies have been introduced over the last decade in order to improve the outcome of gastroschisis after the delivery.

These are represented by:

• Amnioexchange procedure, in order to reduce the exposure of herniated bowel to the amniotic fluid and inflammatory factors (cytokines, IL, TNF, pH). The procedure was abandoned after a study trial due to high mortality rates^(9,10). Amnioexchange is not currently recommended as a potential treatment option for gastroschisis.
• Fetoscopic intervention via closure of the defect in utero or intestinal coverage with a synthetic bag (similar to silo placement), but so far, this kind of interventions have proved technically unsuccessful.
• The newest approach to prenatal gastroschisis is the use of mesenchymal stem cells termed transamniotic stem cell therapy (TRASCET). The theory behind TRASCET is that augmentation of the biological role of native stem cells within the amniotic fluid may target the tissue repair, and this shows great promise for the future^(11,12).

Case presentation

We present the case of a primigravida patient with a fetus diagnosed with gastroschisis at 13 weeks of gestation by ultrasound examination with Voluson E10, along with the final outcome and postpartum management of the AWD of the baby.

A 24-year-old patient, M.C., presented in our clinic for her first-trimester screening ultrasound. She was primigravida, Rh negative, with Rhesus incompatibi­lity, with not known associated risk factors, no alcohol, tobacco or illicit drug use.

At the ultrasound examination, we found a single intrauterine pregnancy with no markers of aneuploidies, CRL corresponding to the LMP, DV, NB, TV, uterine arteries PI normal, gastroschisis associated, confirming an AWD on the right of the umbilical cord (Figures 1, 2 and 3).
 

After the diagnosis of gastroschisis, the patient chose to perform fetal cell-free DNA testing that returned negative for aneuploidies.

Then she was referred to a tertiary clinic center for the management and follow-up of the pregnancy. There was an uneventful course of pregnancy until 35 weeks and 3 days of gestational age, when she returned to our clinic for abundant vaginal discharge. A sample from the discharge was sent to the lab which turned out positive for E. coli with sensitivity to ampicillin. The next day, she reported discharge of amniotic fluid; we tested, and it was positive for membrane rupture.

The cervix was long, with no uterine contraction, and she was sent for the planned caesarean section at the tertiary clinic, where she was under care during the pregnancy.

The ultrasound at the moment of our presentation showed a baby of 35 weeks and 3 days, with an estimated fetal weight of 2100 g (Figure 4).
 

The bowel loops were freely floating in the amniotic fluid, with no dilatation more the 3 cm, and no other organs herniated. The AWD was not closed, and the amniotic fluid was normal the day before the rupture of membranes.

At the caesarean section, it was delivered a baby boy of 2200 g, with an Apgar score of 8, Rh positive (Figure 5).
 

The baby was transferred at the pediatric ward, where he was scheduled for care in the first two hours of the delivery. There they put the baby’s bowell under the Silo balloon and the bowels completely returned in the abdomen by the seventh day of life, and the next day the AWD was surgically sutured (Figures 6 and 7).
 

The baby was discharged from the hospital one month after the delivery, and no complications occurred.

It resulted that, in our case, this was an uncomplicated gastroschisis (Figure 8).
 

Conclusions

Fetal abdominal wall defects are a complex group of conditions that may have a large spectrum of associated structural anomalies, accompanied or not by aneuploidies.

The correct diagnosis and the classification of these defects have a crucial importance, because these play an important role in the counseling of future parents during the pregnancy, as well as in offering support in specialized centers for the proper management in order to reduce morbidity and mortality.

Gastroschisis is associated with a risk of intrauterine demise of 5%.

An important role is attributed to the physician and the diagnosis of this anomaly as early as possible, along with the collaboration with the team of maternal-fetal specialists, as well as pediatric surgeons with expertise and neonatologists. Doctors should provide parents with   genetic counseling and complete information of complications that may arise during pregnancy, including fetal demise and long-term outcomes: motility disfunction, short gut syndrome, neonatal gastroesophageal reflux, especially after the repair⁽⁷⁾.

The complications are more frequent with preterm labor, and babies with abdominal wall defects are more prone to be small for the gestational age.

No genetic mutations are known to cause an AWD, and the disorder may imply multiple genetic and environmental factors, most of them hardly to detect.

It is important for parents to know that most cases with gastroschisis and other abdominal wall defects are sporadic.

We emphasize not only the importance of early diagnosis, but also the importance of prompt and careful search for other abnormalities, even though there is no close association with aneuploidies. At the same time, we underline the importance of frequent follow-up of babies with abdominal wall defect in specialized tertiary clinics. 

Abbreviations: AWD – abdominal wall defect; POC – pentalogy of Cantrell; GA – gestational age; AFP – alpha-fetoprotein; TRASCET – transamniotic stem cell therapy; CRL – crown-rump length; LMP – last menstrual period; DV – ductus venosus; NB – nasal bone; TV – transvaginal; UC – umbilical cord

Autori pentru corespondenţă: Doiniţa Pariza E-mail: doinitagache@yahoo.ca

CONFLICT OF INTEREST: none declared.

FINANCIAL SUPPORT: none declared.

This work is permanently accessible online free of charge and published under the CC-BY.