Ultrasonic study of amnioinfusion. A report of two cases.

Two patients had amnioinfusion with subsequent improvement in fetal heart rate (FHR) patterns. Ultrasound in case 1 showed a pocket of saline around the umbilical cord and improved FHR. Case 2 likewise had an improvement in the FHR without ultrasonic evidence of a protective pocket of fluid. Case 2 actually had a tight true knot in the cord, which explained the abnormal FHR pattern. Amnioinfusion can form a protective pocket of fluid around the umbilical cord in cases of severe oligohydramnios, although in our experience its success rate is low and unpredictable.