It is a condition that may occur during pregnancy when the placenta implants in the lower part of the uterus and obstructs the cervical opening.
Causes and risks
Possible causes of placenta previa include a scarred endometrium (lining of the uterus), a large placenta, an abnormal uterus, or an abnormal formation of the placenta. The incidence of placenta previa is approximately 1 out of 200 births. The incidence increases with each pregnancy, and it is estimated that the incidence in women who have had 6 or more previous deliveries may be as high as 1 in 20 births. The incidence is doubled in multiple pregnancy (such as twins and triplets).
Prevention
This condition is probably not preventable.
Symptoms
- Spotting during the first and second trimesters
- Sudden painless and profuse vaginal bleeding in pregnancy during the third trimester (after 28 weeks)
- Uterine cramping may occur with onset of bleeding.
- Bleeding may not occur until after labour starts in some cases.
An abdominal ultrasound performed during the second trimester indicates low positioning of the placenta.
Treatment
Early in pregnancy, transfusions may be given to replace maternal blood loss and medications given to prevent premature labour, prolonging pregnancy to at least 36 weeks. Beyond 36 weeks, the benefits of additional maturity have to be weighed against the potential for major hemorrhage.
Cesarean section is the preferred method for delivery. It has proven to be the most important factor in reducing maternal and death rates.
