'Anteroposterior placenta': a novel, simple sonographic feature indicating benign vaginal bleeding in early pregnancy.

This study proposes a sonographic feature of the placenta in association with benign vaginal bleeding. A total of 286 normal singleton pregnancies were examined for 'anteroposterior, AP, placenta', which was reported when the placenta was attached to both anterior and posterior walls of the uterus in sagittal transabdominal ultrasound scans. Pregnancies were followed up by week 20. AP placenta, vaginal bleeding and spontaneous abortion were documented in 61 (21.3%), 44 (15.4%) and 2 (0.7%) pregnant women, respectively. AP placenta was significantly more common in the group with vaginal bleeding (54.5% vs 1.3%, p < 0.001, odds ratio = 6.65 with a 0.95 confidence interval of 3.34-13.24). Abortions occurred only in patients with vaginal bleeding and no AP placenta (10% vs 0%; p = 0.20). In a normal clinical pregnancy with no known risk of miscarriage, the presence of an AP placenta usually forecasts a benign vaginal bleeding/spotting in first 20 weeks of gestation.