Utilizing two-dimensional ultrasound to develop normative curves for estimated placental volume.

OBJECTIVE The objective of this study was to use two-dimensional (2D) ultrasound (US) during routine prenatal surveillance to develop normative estimated placental volume (EPV) growth curves. STUDY DESIGN Patients ≥ 18 years old with singleton pregnancies were prospectively followed from 11 weeks gestational age (GA) until delivery. At routine US visits, placental width, height, and thickness were measured and EPV calculated using a validated mathematical model. RESULTS In this study, 423 patients were scanned between 9.7 and 39.3 weeks GA to generate a total of 627 EPV calculations. Readings were clustered at 12 and 20 weeks, times of routine scanning. The mean EPV was 73 ± 47 cc at 12.5 ± 1.5 weeks (n = 444) and 276 ± 106 cc at 20 ± 2 weeks (n = 151). The data best fit a parabolic function as follows: EPV = (0.384GA - 0.00366GA(2))(3). Tenth and 90th percentile lines were generated with ± 1.28 SE offset. EPV readings below the 10th or above the 90th percentiles tended to be associated with either small or large newborns, respectively. CONCLUSION Routine 2D US created EPV growth curves, which may be useful for stratifying patients into prenatal risk groups.