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

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