Amnioexchange for the treatment of gastroschisis - An in vitro study to determine the volume and number of exchanges needed

Objective: Intestinal damage of neonates with gastroschisis is thought to be attributed to prolonged exposure to the toxic environment of the amniotic fluid. Amnioexchange/infusion has been a proposed method to improve bowel quality. The aim of the current study was to design an in vitro model to determine the volume and number of amnio-exchanges needed to achieve a predetermined reduction in a solute contained within the original concentration of amniotic fluid. Methods: We used a predetermined volume of normal saline to serve as the model for the amniotic cavity and the chloride anion as the surrogate for the noxious agent. Volumes of 250, 500, and 750 ml were used to represent the amniotic volume at different gestational ages. We performed a series of exchanges based on our calculated formula for each respective volume. The Student t test was used to calculate the differences between our expected and observed mean chloride concentrations (p < 0.05 = significance). Results: The mean baseline chloride concentration was 100 mmol/l for each volume. Our formula overestimated the number of exchanges needed to reach a 75% reduction in chloride concentration for each volume, but this was not statistically significantly different from the observed number of exchanges (p < 0.05). Conclusion: Our formula required a correction factor of 3 or 4 fewer exchanges to obtain the desired 75% reduction in chloride concentration. It may be useful when investigations to study amnioexchange are undertaken for the treatment of fetuses with gastroschisis. Copyright (C) 2007 S. Karger AG, Basel.