Reproducibility of 3-dimensional sonographic measurements of fetal and placental volume at gestational ages of 11-18 weeks

Purpose. Determine the reproducibility of 3D ultrasound (3DUS) measurements of fetal and placental volumes. Methods. We included 34 pregnant women between gestational weeks (GW) 11-18. Two operators independently acquired fetal and placental volumes using 3DUS. Each volume was acquired twice and stored on disk for off-line analysis. Intra- and interobserver reproducibility was expressed in the intra- and interclass correlation coefficient (intra-CC and inter-CC). In addition, the 3DUS volumes acquired by the first operator were calculated by the second and vice-versa to evaluate the effect of volume acquisition and caliper placement. A value >0.75 was considered a good agreement. Results. Fetal and placental volume measurements were successful in 97% of all cases. Between GW 11-14 and 14-18 the median fetal volume was 20.8 (5.0-35.1) and 51.7 (37.9-132.8) ml, the median placental volume was 71.3 (40.9-111.9) and 120.7 (94.2-273.7) ml. Bland-Altman plots were used for statistical analysis. The intraobserver reproducibility was good for fetus (intra-CC: 0.99; 0.99) and placenta (intra-CC: 0.99; 0.98). Also, interobserver reproducibility was good for fetus (inter-CC 0.98) and placenta (inter-CC 0.98). In addition, regardless of the operator who acquired the volumes, the inter-CC remained good for both fetus (inter-CC: 0.99; 0.99) and placenta (inter-CC: 0.97; 0.99). Conclusion. The reproducibility of fetal and placental volume measurements by 3DUS between GW 1118 is good. In addition, individually chosen caliper placement and volume acquisition has no effect on the calculation of either volumes. (C) 2007 Wiley Periodicals, Inc.