A retrospective cohort study of pregnancies with placenta previa detected during ultrasound was done. This is to evaluate gestational age at ultrasound detection of placenta previa as a predictor of previa persistence unitl delivery and to estimate the effects of previa type, parity, and prior cesarean delivery on previa persistence. The outcome of the study was persistent placenta previa resulting in cesarean delivery. Statistical analysis were performed using X? for categoric outcomes. A total of 82 women were found to have placenta previa on antepartum ultrasound examination based on the MMC ultrasound database from January 1, 2000 to December 31, 2001. Data were grouped according to trimesters. Of women diagnosed with previa in the 1st trimester 7% had previa at delivery, while 29% and 22% of women with previa in the second and third trimesters respectively have previa at delivery. Regardless of gestational age at detection, complete previas were more than twice as likely to persist until delivery than incomplete previas. Women with prior cesarean delivery were at an increased risk for persistence of previa, if previa was detected in the 2nd and 3rd trimester. Parity was no longer a risk factor for previa persistence.

Makati Medical Center Proceedings, 2004 (18) pages 49-52