Placenta Previa: When Your Placenta Blocks the Cervix

Placenta Previa: When Your Placenta Blocks the Cervix

In some pregnancies, the placenta attaches low in the uterus and just above the cervix. This blocks delivery through the cervix. Find out more about this serious condition.

The placenta is your unborn baby’s life support system. It connects the baby to your blood supply, delivers nutrients and oxygen to the developing fetus and removes its waste. The placenta also plays a vital role in protecting your unborn baby from infections and dangerous substances. But sometimes this life-sustaining organ can literally get in the way of birth.

What is placenta previa?

At first, the placenta develops in the lower part of the uterus. As the uterus grows and stretches, the placenta is usually repositioned toward the top or side of the uterus.

Placenta previa occurs when the placenta settles low in the uterus. Here it can partially or completely block the entrance to the cervix, the opening to the vagina. This can cause bleeding and sometimes contractions. It can also prevent normal vaginal delivery.

Luckily, placenta previa is nearly always diagnosed by ultrasound testing before labor and delivery, so problems can be prevented. All women with placenta previa typically need to deliver by cesarean section.

Types of placenta previa

There are 3 different kinds of placenta previa.

  • Complete: the opening to the cervix is fully blocked.
  • Partial: the opening to the cervix is partially blocked.
  • Marginal: the placenta is at the edge of the opening of the cervix, but does not block it.

What are the symptoms?

The most common sign of placenta previa is vaginal bleeding during the second half of pregnancy. If you have vaginal bleeding, call your doctor right away.

How is it diagnosed?

Placenta previa is usually found during routine ultrasounds as part of your normal prenatal care. The doctor may also do an ultrasound if he or she suspects placenta previa because of bleeding.

How is it treated?

The treatment options depend on how serious your bleeding is and how far along you are in your pregnancy.

If you’re diagnosed during the first half of your pregnancy, there is a good chance the condition will correct itself without treatment.

Later in pregnancy, bed rest and frequent doctor visits are often part of the treatment plan. Your doctor may admit you to the hospital and monitor you there until the baby is born. If the bleeding is serious, an emergency c-section may be needed.

If you are sent home, your doctor may suggest that you avoid doing certain things that may make the bleeding worse. These instructions may include:

  • Do not have sexual intercourse (this is called pelvic rest)
  • Do not have pelvic exams
  • Limit traveling

What causes it?

The cause of placenta previa is unknown. Certain women are at a higher risk, though. You may be at risk if you:

  • Smoke cigarettes
  • Have fibroids
  • Are 35 years or older
  • Have had previous uterine surgeries – including c-section, abortion or a D&C procedure (dilation and curettage)
  • Are pregnant with multiple babies
  • Have had other pregnancies
  • Have had previous placenta previa
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