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Placenta Previa

What is placenta previa?

Normally, the placenta attaches high on the uterus wall, away from the cervix. In placenta previa, the placenta is covering or near the opening to the cervix and makes it impossible or dangerous for baby to pass through the birth canal. This happens in less than 1% of pregnancies.

Often, as the uterus grows during the first 3 months of pregnancy, a low-lying placenta moves away from the opening of the uterus. If the placenta does not move up and out of the way, it is called previa. If the placenta is previa, you will have to be delivered by cesarean section.

How does it occur?

Placenta previa occurs when the fertilized egg attaches to the lower part of the uterus instead of the top or sides of the uterus.

Some women are at higher risk for this condition than others. The risk for placenta previa is greater for women who:

  • are older than 35
  • have had more than one previous delivery
  • have had many abortions
  • are carrying twins
  • have had previous uterine surgery involving the lining of the uterus
  • are smoking
  • have had a cesarean section
  • have had placenta previa before.

What are the symptoms?

The first sign of placenta previa is sudden, painless bleeding during the second or third trimester of pregnancy. Bleeding may begin moderately and become severe. Bleeding may not occur until after labor starts in some cases. Sometimes this bleeding can be confused with a type of light bleeding that often occurs during normal labor, called the bloody show. There is usually no pain, tenderness, uterine contractions, or cramps, although these symptoms may occur.

In some cases, placenta previa may cause the baby to grow more slowly. This is called intrauterine growth retardation (IUGR).

How is it diagnosed?

Placenta previa is usually detected by ultrasound scans. If it is diagnosed early in pregnancy, you should expect to have several other ultrasound scans in order to check on the location of the placenta to see if it resolves.

If bleeding occurs with the placenta previa, blood tests will be done to determine the amount of blood loss that occurred.

How is it treated?

Treatment depends on how much bleeding you have had. The results of blood tests will help to determine if you need a blood transfusion. The decision to deliver the baby will depend on how far along the pregnancy is and how heavy the bleeding is. If you have severe bleeding, the baby is usually delivered by cesarean section as soon as possible to save your life and the life of your baby.

If you have bleeding and it is before 37 weeks in the pregnancy, the doctor may recommend:

  • bed rest
  • staying in the hospital
  • ultrasound tests every 1 to 4 weeks if the bleeding stops
  • nonstress tests or biophysical profiles to make sure the baby is doing well
  • oral iron or a blood transfusion if your blood count is too low.

If you have two or three bleeding episodes before 37 weeks, the doctor may recommend:

  • bed rest or staying in the hospital
  • a drug to stop contractions if the bleeding is caused by contractions of the uterus (although sometimes this may cause the bleeding to increase)
  • amniocentesis to see if the baby's lungs are mature enough for delivery.

If the placenta does not completely cover the opening to the uterus, the doctor may allow you to go into labor. If Dr. Hardy thinks you can deliver the baby through your vagina, you will be monitored closely. At the first sign of increased bleeding you may need a cesarean section to deliver the baby.

If the placenta does completely cover the opening of the uterus, a cesarean section is the only way to deliver the baby safely.

What are some of the complications of a placenta previa?

There are some serious complications that may occur with a placenta previa and they are:

  • any change in the cervix, can cause the placenta to bleed as I separates from the uterus
  • premature delivery, or possible fetal death, if extensive placenta previa develops before the expected delivery date
  • hazardous blood loss that could lead to shock and death
  • blood transfusions for the mother prior to delivery or following delivery
  • poor fetal growth due to an abnormal placenta providing a decreased blood flow and oxygen delivery
  • congenital abnormalities or fetal anemia

How can I take care of myself?

Report any bleeding to your doctor. To prevent bleeding, cut back on your regular activity or just rest in bed. Do not put anything into your vagina, such as a tampon, because it may cause more bleeding. Do not have sexual intercourse.

If your doctor prescribes iron, be sure you take it. It is best to take iron after meals so it will not upset your stomach.

What can be done to help prevent placenta previa?

There is nothing you can do to prevent placenta previa. To help prevent complications of a previa:

  • Follow your doctor's instructions.
  • Lie down most of the time.
  • Tell your doctor if you have any pain, contractions, or bleeding.