In gastroschisis, the protruding intestine is usually shortened, thickened, and covered with a fibrous peel. Urine components, which are increased in the amniotic fluid with the onset of renal function, are responsible for these changes. In the chick embryo model of gastroschisis, the authors performed amnio-allantoic fluid exchange to reduce the effect of urinary products. There were three study groups: control, gastroschisis only, and gastroschisis plus exchange. There was a significant decrease in creatinine (P < .05) and a slight decrease in urea concentrations in the gastroschisis-plus-exchange group compared with the gastroschisis-only group. Whereas macroscopic and microscopic studies showed severe fibrosis and bowel-wall thickening in the latter group, the bowel was normal or slightly oedematous in the former. On the basis of this study, the authors suggest that antenatal amniotic fluid exchange might reduce the bowel damage in human foetuses.