Objective: We sought to determine whether novel approaches to volumetric assessment of the early placenta can yield significant predictors of adverse outcome.
Methods: We measured placental volume (PV) at 11 to 14 weeks using virtual organ computer-aided analysis and normalized the PV to the crown-rump length (CRL) to yield the placental quotient (PQ = PV/CRL). We also calculated the mean placental diameter (MPD) from 4 measurements taken at 45 degrees intervals to serve as a surrogate for the fetal-maternal surface area. On the fetal side, the distance from the cord insertion (CI) to the placental margin was measured every 45 degrees. Mean cord distance (MCD) is proposed as a novel descriptor of the chorionic plate and CI. Sonographic variables were analyzed as predictors of a composite adverse pregnancy outcome (COMP = small for gestational age [SGA], preeclampsia, spontaneous preterm birth, or neonatal intensive care unit admission).
Results: A total of 135 patients were included, and 40 (29.6%) had an adverse outcome. The mean PQ (P = .02) and MCD (P = .02) were significantly lower in patients with COMP, although MPD was not significantly different (P = .26). A PQ of less than 1.00 (relative risk [RR], 2.3 [95% confidence interval, 1.4-2.7]) and an MCD of less than 4.00 cm (RR, 1.8 [1.1-2.9]) conferred an increased risk for COMP. Prediction models adjusting for parity and race yielded favorable characteristics [PV: area under the curve [AUC], 0.796; P = .04; PQ: AUC, 0.802; P = .03; MCD: AUC, 0.800; P = .04; and MPD: AUC, 0.782; P = .07). Secondary models targeting SGA as the sole outcome also showed excellent prediction (PV: AUC, 0.820; PQ: AUC, 0.810; MCD: AUC, 0.827; and MPD: AUC, 0.795).
Conclusions: In addition to volume, 3-dimensional sonography allows for novel techniques to measure other aspects of gross placental morphologic characteristics and CI, which can yield promising biologically plausible early predictors of fetal growth and adverse perinatal outcome.