Three-dimensional placental volume measurements between 11 and 13 weeks' gestation.

We sought to determine whether three-dimensional (3D) placental volume measurements can be assessed in normal pregnancies between 11 and 13 weeks' gestation with good intraobserver accuracy. Twenty normal pregnancies were included. Placental volume was determined twice, using the virtual organ computer-aided analysis method. Three-dimensional placental volume measurements were performed by a single physician. Patients with multiple pregnancies, first-trimester bleeding, and abnormal placental appearance were excluded. Intraobserver reliability was evaluated by kappa analysis, and Student T test was performed for continuous variables. Mean placental volume (MPV) was 67.5 +/- 26.7 mL (3) between 11 and 13 weeks' gestation. No significant differences were noted between the two examinations performed (MPV of 67.5 +/- 26.7 mL (3) during the first versus 65.6 +/- 29.1 mL (3) during the second examination; p = 0.826). Moreover, the intraobserver agreement was excellent as indicated by kappa of 0.8. Placental volume can be assessed by 3D sonography between 11 and 13 weeks' gestation with minimal deviations. Nevertheless, the broad variability in placental volume with a wide standard deviation makes its clinical significance questionable.