The incidence of placental residues after vaginal delivery and cesarean section

We studied the incidence of and risk factors for placental residues in 24391 deliveries at our institution between 1989 and 2000. Seventeen patients had a placental residue diagnosed within 16 months of delivery and two patients (0.01%) developed a placental polyp. Uterine anomalies were significantly more common in women with placental residues compared with a matched control group (32% vs. 7%, P < 0.05). Parity, blood group, prior gynecologic surgery, smoking, stillbirth or abortion, succenturiate placenta, mode of delivery, birthweight and mode of placental separation were not associated with placental residues.