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Placenta Previa
- Overview, Causes, & Risk Factors
- Symptoms & Signs
- Diagnosis & Tests
- Prevention & Expectations
- Treatment & Monitoring
- Attribution
Overview, Causes, & Risk Factors
When the placenta implants over or near the inner opening of the cervix, the condition is called placenta previa. The cervix is the opening of the uterus. As the cervix dilates during labor, the abnormal location of the placenta may cause heavy vaginal bleeding and keep the baby from traveling through the birth canal.
What is going on in the body?
Placenta previa occurs in 1 out of 200 births. In about 10% to 20% of these cases, the placenta covers the entire cervix. This is complete placenta previa. Otherwise, only part of the cervix is covered. This is called partial placenta previa.
Vaginal bleeding typically occurs:
The extent of the bleeding depends upon how much of the placenta covers the cervix and how many blood vessels are torn.
What are the causes and risks of the condition?
A woman is more likely to have this condition if:
Symptoms & Signs
What are the signs and symptoms of the condition?
Though symptoms differ, they may include:
Diagnosis & Tests
How is the condition diagnosed?
Every woman with vaginal bleeding who might have this condition should be hospitalized and evaluated. The bleeding may become a hemorrhage without warning.
Tests include:
In many cases, placenta previa causes no symptoms and detected only by pregnancy ultrasound in the early second trimester. In these cases, no symptoms may ever occur and the placenta later may become normally situated.
Prevention & Expectations
What can be done to prevent the condition?
There is no known way to prevent this condition.
What are the long-term effects of the condition?
When a partial placenta previa is found early in pregnancy, it may be managed or change so that a vaginal birth is possible. Complete placenta previa usually calls for a cesarean section when the fetus is mature or if the mother starts to bleed heavily.
In some cases, the mother:
While the mother is usually fine, birth trauma or a hemorrhage may harm the baby. In 15% to 20% of cases, the baby dies. This may be due to not getting enough oxygen in the uterus, prematurity, or other causes of fetal distress.
What are the risks to others?
Complications may harm the baby or cause its death.
Treatment & Monitoring
What are the treatments for the condition?
Treatment varies depending on:
In asymptomatic or mild cases, bedrest and no sexual intercourse may be advised. As the uterus grows, the placenta may move to a safer position. Other treatment may include:
Once a fetus is 36 weeks old, a cesarean section is generally done to avoid potential complications for mother and baby. First, though, tests may be done to check fetal maturity.
What are the side effects of the treatments?
The treatments for this condition may be lifesaving. Possible side effects should be weighed against the loss of life. Any surgery can cause bleeding and infection. Blood transfusions and medications can cause allergic reactions.
What happens after treatment for the condition?
After the birth, the woman will be watched closely for signs of continued bleeding through:
If the baby survives, he or she will be monitored in the intensive care unit.
How is the condition monitored?
A woman will be closely monitored throughout pregnancy to determine the status of the fetus, as well as her own health.
Attribution
Author:Eva Martin, MD
Date Written:
Editor:Coltrera, Francesca, BA
Edit Date:07/19/00
Reviewer:Eileen McLaughlin, RN, BSN
Date Reviewed:06/07/01