Does Looking at the Placenta Improve First-Trimester Screening? Placental Volume, Vascular Indices and Fetal Growth Disorders in an Unselected Cohort

Background/Objectives: Fetal growth disorders and hypertensive disorders of pregnancy share pathophysiological pathways rooted in impaired first-trimester placentation. We asked whether three-dimensional placental volume and the VOCAL vascular indices add prognostic information to first-trimester screening and how repeatable and setting-dependent they are. Methods: A prospective cohort of 445 singleton pregnancies was scanned at 11+0–13+6 weeks, twice each at two pulse repetition frequencies (2.3 and 0.9 kHz). Markers were converted to crown–rump-length-adjusted z-scores. The primary analysis tested the incremental value of volume over clinical risk factors plus PAPP-A for a composite of hypertensive disorders, fetal growth restriction or small-for-gestational-age birth, with bootstrap optimism correction (1000 resamples). Results: The composite outcome occurred in 69/407 women (17.0%). Volume was repeatable (intraclass correlation 0.90) and not measurably associated with maternal adiposity, whereas the indices differed threefold between paired acquisitions obtained at different settings, varied between operators and fell with body mass index. Volume was associated with the outcome independently of clinical risk factors and PAPP-A (likelihood-ratio p < 0.001; odds ratio 0.55 per SD, 95% CI 0.41–0.74) and of the combined preeclampsia-screening components; the corresponding increase in the area under the curve was small (optimism-corrected 0.59 to 0.66) and not significant by DeLong’s test (p = 0.13), and calibration slopes indicated overfitting. The indices showed no consistent incremental value. Small placentas preceded growth restriction (composite outcome 45% below the study-derived 5th centile), and large placentas preceded large-for-gestational-age birth. With four cases of preeclampsia, the study is uninformative for preeclampsia-specific prediction. Conclusions: First-trimester placental volume is a reproducible marker, not measurably associated with maternal adiposity, which was independently associated with fetal growth disorders in this cohort; the resulting gain in discrimination was small and its clinical value is unproven. Aspirin use after screening was not recorded. External validation, assessment of reproducibility between operators and analysts, and evaluation of clinical utility are required before any use in practice. The vascular indices are acquisition- and habitus-dependent and showed no consistent incremental prognostic value.