title: Early diagnosis of placenta previa.
abstract: Ultrasound was used as a diagnostic tool in 859 patients for the localization of the placenta in the second trimester prior to genetic amniocentesis. A greater incidence of total placenta previa was found in the study group (5.6%) than is reported for the general population (0.25-0.5%). Maternal age greater than 35 years was the indication or co-factor in 59% of the patients studied, which might explain this difference. It was possible to predict total placenta previa at term early in the second trimester. It was demonstrated that if a placenta was located centrally over the cervical os and did not change position with variations in the degree of bladder-filling or changes in uterine position, the risk of having a total placenta previa at term increased from 1/143 to 1/8 pregnancies.
mesh_terms: D000328:Adult; D000649:Amniocentesis; D002585:Cesarean Section; D005260:Female; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D010298:Parity; D010923:Placenta Previa / Q000175:diagnosis* / Q000601:surgery; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D012306:Risk; D014463:Ultrasonography