Placenta Previa

Placenta previa occurs during pregnancy when the placenta partially or fully covers the opening of the cervix. In a normal pregnancy, the placenta is located at the top or side of the uterus; with placenta previa, however, the placenta is located low in the uterus, blocking the fetus's access to the birth canal. Placenta previa can cause sudden vaginal bleeding, which can range from light to heavy, and be continuous or intermittent. The bleeding may or may not be accompanied by uterine cramping. Placenta previa can also cause complications during delivery, and requires treatment by a physician.

Causes of Placenta Previa

Placenta previa occurs more often in women who have or had the following:

  • An abnormally shaped uterus
  • Many previous pregnancies
  • Large placenta due to a multiple pregnancy
  • Uterine scarring from past surgery

Placenta previa is also more common in women older than 35, and in those who smoke.

Diagnosis of Placenta Previa

Placenta previa is diagnosed after a physical examination and review of symptoms. The diagnosis can be confirmed with abdominal and transvaginal ultrasounds. In rare cases, an MRI scan is used to determine the exact location of the placenta.

Treatment of Placenta Previa

Treatment for placenta previa varies based on the amount of bleeding, how advanced the pregnancy is, how much of the placenta is covering the cervix, and the health of the mother and baby. Treatment may include recommendations for behavior modifications that include the following:

  • Bed rest
  • Abstaining from sexual intercourse
  • Abstaining from exercise or physical activity

Medication may be prescribed to prevent early labor. In extreme cases, in which there is severe bleeding, a blood transfusion may be performed to replace lost blood. In most cases, when labor occurs, a Cesarean section is performed because a vaginal delivery can be dangerous to both the mother and baby. If the placenta covers all or part of the cervix, a vaginal delivery can cause severe bleeding.

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