In‐vivo accuracy of ultrasound measurements of intrauterine ume in pregnancy

Abstract

The accuracy of ultrasonic measurements of intra-amniotic volume using a parallel planimetric area method was assessed in 18 women by comparison against different measures of the same volume space. In nine patients undergoing second-trimester termination of pregnancy amniotic fluid volume was measured using a dye dilution method and fetal volume was measured by either water displacement or calculated from fetal weight. The estimated intra-amniotic volume by this method was not significantly different from the ultrasonic measurement. In one patient who had a hysterotomy, fetal and amniotic fluid volumes showed a difference of 1.01% between ultrasonically-measured and actual intra-amniotic volume. In eight patients studied in the third trimester the mean difference between ultrasonic and estimated intra-amniotic volume at delivery was 6.2%.