Placenta previa

Placenta previa is implantation of the placenta over or near the cervix, in the lower part of the uterus.

Inside the uterus , the placenta may cover the opening of the cervix completely or partially. Placenta previa occurs in 1 out of 200 deliveries, usually in women who have had more than one pregnancy or have abnormalities of the uterus such as fibroids .

Painless vaginal bleeding begins suddenly in late pregnancy and may become profuse. The blood may be bright red. An ultrasound scan helps a doctor make the diagnosis and distinguish a placenta previa from one that's prematurely detached ( abruptio placentae ).

Treatment

When bleeding is profuse, repeated blood transfusions may be needed. When bleeding is minor and delivery isn't imminent, bed rest is usually advised. If the bleeding stops, a woman is usually encouraged to walk. If it doesn't recur, she's generally sent home, provided that she can return to the hospital easily. A cesarean section is almost always performed, because if the woman goes into labor , the placenta tends to become detached very early, depriving the baby of its oxygen supply. In addition, there may be massive bleeding in the mother.

From The Merck Manual of Medical Information – Home Edition , edited by Mark H. Beers and Robert Berkow. Copyright 1997 by Merck & Co., Inc., Whitehouse Station, NJ: http://www.merck.com/mmhe/index.html