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Placenta Previa

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Description of Placenta Previa

Placenta previa is a condition in pregnancy in which the placenta lies below the baby in the uterus and may completely block the opening to the uterus (cervix).

The placenta is an organ that develops in the uterus during pregnancy and allows oxygen, nourishment, and wastes to pass between the mother and the baby.

Most low-lying placentas seen in the first 3 months of pregnancy will go away because as the uterus grows, the 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, the doctor has to deliver the baby early about 50 percent of the time.

How does it occur?

Placenta previa occurs when the fertilized egg attaches to the lower part of the uterus instead of the top 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 a caesarean section
  • have had a previous placenta previa.

What are the symptoms?

The first sign of placenta previa is bright red bleeding or spotting. Sometimes this bleeding can be confused with a type of light bleeding that often occurs during normal labour, called the bloody show. There is usually no pain, tenderness, uterine contractions, or cramps, although these symptoms may occur.

How is it diagnosed?

Tests that may be performed are:

  • ultrasound to see where the placenta is attached in the uterus
  • double setup examinations if there is no time to perform ultrasound or ultrasound is not available
  • a complete blood count to see if the mother is affected by the amount of blood lost
  • a speculum exam to make sure the bleeding is not coming from somewhere else.

How is it treated?

Treatment of the previa depends on the number and amount of bleeding episodes you have. The results of the blood count 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 as soon as possible to save your life.

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

  • bed rest
  • hospitalization
  • ultrasound tests every 1 to 4 weeks if the bleeding stops
  • periodic nonstress tests or biophysical profiles
  • oral iron or a blood transfusion, if necessary.
  • If you have 2 or 3 bleeding episodes, the doctor may recommend:
  • bed rest or hospitalization
  • a drug to stop the contractions if the bleeding is caused by uterine contractions (although occasionally this may cause the bleeding to increase)
  • an amniocentesis to see if the baby’s lungs are mature enough to be delivered.

If the opening to the uterus is not completely covered by the placenta, the doctor may allow you to have labour. If the doctor thinks you could deliver through the vagina, you will be monitored closely.