Transumbilical placement of the vaginal probe in obese pregnant women.

Transabdominal ultrasonography in obese pregnant women is often unsatisfactory because of the poor transmission of ultrasound through a thickened abdominal wall. We report our experience with the placement of a transvaginal probe in the umbilicus to improve resolution in obese pregnant patients. The technique, which involves filling the umbilicus with ultrasound transmission gel and inserting the transvaginal probe into the umbilicus, was applied in 25 consecutive obese patients who had unsatisfactory fetal imaging by the standard transabdominal approach. The most frequent reason for incomplete fetal survey by the standard transabdominal approach was unsatisfactory imaging of the fetal heart (19 of 25 cases, 76%). The transumbilical approach resulted in improved resolution and satisfactory cardiac examination in 18 of these 19 cases (95%). In two cases, color and pulsed Doppler interrogation of intrafetal vessels become possible. A complete fetal survey was accomplished in 96% of the cases.