Radiological Diagnosis

GASTROSCHISIS WITH CAUDAL REGRESSION SYNDROME

Transverse scan of the fetal abdomen [Figure - 1] & [Figure - 2] shows herniation of the gut loops through the defect in the anterior abdominal wall. The loops of bowel are dilated, echogenic and thick walled. There is no membrane covering the herniated contents. Liquor also is reduced in amount. Sonogram in coronal plane [Figure - 3] shows spine upto mid thoracic level with absent lower thoracic & lumbar spine, and sacrum. Liver is seen floating freely in the amniotic cavity. Sonogram in mid-sagittal plane [Figure - 4] shows normal brain, cranio-vertebral junction with absent lower spine as described. Other sonographic findings included - absent both the lower extremities and absent bilateral kidneys.

An antenatal diagnosis of Gastroschisis with possibility of Caudal Regression syndrome was thought (because occurrence of Gastroschisis is usually not associated with other anomalies). Patient consented for termination of pregnancy. Postnatal autopsy confirmed the findings.

Gastroschisis, from the Greek word meaning " belly cleft " is a relatively small defect (2 to 4 cm) in the abdominal wall involving all the layers of abdominal wall lateral (usually right side) to the intact umbilical cord [1],[2],[3]. The abdominal contents herniate through this small defect in utero and are free floating with in the amnion without any covering membrane unlike Omphalocele [2],[3]. Most commonly it's the small bowel which eviscerates often accompanied by the large bowel and sometimes stomach but liver & other solid organs are rarely involved [1],[2],[3],[4]. Almost all the patients with Gastroschisis demonstrate either bowel malrotation or nonrotation. Intestinal ischemia or stenosis may be present in 1/3rd of cases. This ischemia may lead to bowel gangrene, perforation, or meconium peritonitis [2],[3],[5]. The umbilical cord inserts in anterior abdominal wall, which distinguishes it from Omphalocele where cord inserts into the sac [5]. Fetuses having Gastroschisis are more often associated with prematurity and intrauterine growth retardation.

Gastroschisis is generally sporadic with incidence of 1 in 10,000 live births but its occurrence with other anomalies is rare [2]. Theories regarding this defect include abnormal involution of the right umbilical vein or disruption of the omphalo-mesentric artery with ischemia [1],[2].

As described above Gastroschisis is rarely associated with extra gastrointestinal abnormalities, but in our case it was associated with Caudal Regression syndrome. Caudal Regression syndrome is a consequence of abnormal development of structures derived from the caudal mesoderm of the embryo before the fourth week of gestation and extended to various cranio-vertebral levels. Maternal diabetes, genetic predisposition and vascular hypoperfusion have been reported as possible causative factors [2],[3],[6],[7]. Caudal Regression syndrome is characterized by absent sacrum and variable portion of lumbar and even thoracic spine, and abnormalities of pelvis & lower limbs. If the entire sacrum and lower lumbar vertebral segments are absent, the iliac bones may be opposed or fused. The femurs may be shortened because of hypoplasia. The feet may be clubbed. Other anomalies associated with this syndrome include a spectrum of gastrointestinal tract anomalies (tracheoesophageal fistula, duodenal atresia, imperforate anus), genitourinary (renal agenesis, obstruction, renal cystic dysplasia or malrotation), heart and CNS (anencephaly and spina bifida) [3],[7]. Severe oligohydramnios may be present because of lethal renal anomalies.