Composition of amniotic fluid with experimental jejuno-ileal atresia

The possibility that the composition of amniotic fluid is significantly altered with fetal intestinal obstruction was examined in 15 normal, 15 sham operated and 15 ewes in which jejuno-ileal atresia was created by devascularizing a 15 cm intestinal segment in the fetus at 90--100 days gestation. Samples of amniotic fluid for osmolality, urea N, creatinine, electrolytes, amylase, lipase, bilirubin, and proteins were obtained at 100 days gestation and at C-section performed 5 days prior to the anticipated date of delivery. One sham operated and four operated fetuses aborted prior to term for an 83% overall fetal survival rate. All surviving operated animals had total intestinal obstruction with the classical appearance of jejuno-ileal atresia. The volume of amniotic fluid at term varied from gelatinous material to as much as 1.0 liter of clear yellow to dark orange fluid. Amniotic fluid composition in term animals was not significantly different from those at 100 days gestation when the creatinine was below 15 mg%. However, sodium and chloride were significantly elevated in all groups at term when the creatinine was above 15 mg%. The osmolality and urea N in the latter group was not significantly different from animals at 100 days gestation. The amylase, lipase, total proteins, albumin, total and direct, and bilirubin in control animals at term was not significantly different from sham operated and experimental subjects. This study suggests that routine amniocentesis in the "high risk" patient would not be diagnostic of fetal intestinal obstruction.