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.