Low-lying placenta.

Routine ultrasonographic examinations were performed in 255 pregnant women. Most of the patients (95%) had the examination prior to 32 weeks of gestation. In 16 patients (6%) the placenta was identified as low-lying placenta or placenta previa. Of those 16 patients, the placenta was located on the anterior wall in 6, on the posterior wall in 7, and on both the anterior and posterior walls in 3. Ultrasonographic follow-up examination showed conversion to normal position in 10 of those 16 patients (63%). Three of the 7 patients with posterior placentas and all 3 of the patients with placentas located on both posterior and anterior walls failed to demonstrate conversion of the placenta to a normal position. Bleeding complications were also more common in those 2 groups.