Gastroschisis in the partially extraamniotic fetus: experimental study.

The short, thick, matted bowel, often found in gastroschisis, has been attributed to a variety of factors. We designed an original animal model in order to isolate the effect of amniotic fluid on the fetal bowel. We created experimental gastroschisis in fetal rabbits. Extruded bowel was kept out of the amniotic sac in half of the operated fetuses. At term, 7 days after surgery, 21 surviving fetuses (12 intraamniotic gastroschisis [IAG] and 9 extraamniotic gastroschisis [EAG]) and 16 control littermates were collected for study. Five parameters were measured in each animal: body weight, intestinal weight, intestinal length, bowel diameter, and bowel wall thickness. Fetal mortality due to the extraamniotic fixation technique was 25%. We found no statistically significant difference in body weight, intestinal weight, or bowel wall thickness. An enormous difference was found in intestinal length (P < .0001 among the three groups). Bowel diameter was significantly different (P = .02) in the extreme groups (IAG and controls), with the intestine being more dilated in IAG than in EAG and controls. Gastroschisis in the absence of amniotic fluid was not as damaging to the fetal intestine as "natural" intraamniotic gastroschisis.