Amniotic fluid volume responses to esophageal ligation in fetal sheep: contribution of lung liquid.

Objective: The objective of the study was to determine the amniotic fluid volume (AFV) response to fetal esophageal ligation with and without fetal lung liquid entering the amniotic sac.

Study Design: AFV was measured in 3 groups of late-gestation ovine fetuses: time controls, tracheoesophageal shunted, and esophageal ligated.

Results: One day after surgery, AFV was similar in all groups, averaging 1064 +/- 66 mL. On postsurgical day 9, AFV was unchanged in control fetuses, increased to 3025 +/- 294 mL in fetuses with esophageal ligation and lung liquid shunted into the fetal stomach, and to 3437 +/- 430 mL in fetuses with esophageal ligation and no shunting.

Conclusion: AFV expanded gradually following esophageal ligation to the highest volume thus far reported in noninfused ovine fetuses. Lung liquid entry into the amniotic sac altered neither the time course nor the extent of the AFV increase following esophageal ligation.