Placenta Previa

 
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: · as the lower part of the uterus starts to widen and thin out as the uterus grows in the later part of pregnancy · as the cervix opens during labor, which tears blood vessels in the placenta · with trauma to the placenta, as with the pressure of the penis during intercourse

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 signs and symptoms of the condition?

Though symptoms differ, they may include: · sudden, painless, bright red vaginal bleeding, usually in the later half of pregnancy · painless vaginal bleeding after sexual intercourse · uterine cramping with the bleeding · bleeding during labor

What are the causes and risks of the condition?

A woman is more likely to have this condition if: · she has had 6 or more births · she is carrying two or more fetuses · she previously had a cesarean section · she is older than 35 years · the placenta is large or abnormal

What can be done to prevent the condition?

There is no known way to prevent this condition.

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: · a pregnancy ultrasound to check the placenta's location and rule out placenta abruptio, or separation of the placenta from the uterine wall · continuous fetal monitoring to assess the baby's well-being · finding the fetus's position by feeling the mother's abdomen. In about one-third of the cases of placenta previa, the baby is lying sideways or buttocks-first in the uterus. · complete blood counts, or CBCs, to follow the mother's blood losses

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.

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: · suffers blood loss and shock · gets an infection · develops an embolism or blood clot · must have a hysterectomy if the placenta will not separate from the uterus

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.

What are the treatments for the condition?

Treatment varies depending on: · the amount of bleeding · the age of the fetus · the well-being of the fetus · whether the condition is complete or partial · the position of the fetus · the mother's well-being · whether labor has begun

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: · using fetal monitors as needed · giving the mother fluids through a vein · monitoring the mother's vital signs, such as blood pressure, heart rate, and urine output · observing, but not interfering with, the pregnancy if tests and signs suggest mother and fetus are fine · giving the mother blood transfusions to replace lost blood if the fetus is immature, not in distress, and younger than 36 weeks old · allowing a vaginal birth if the mother and fetus are stable · giving the mother a cesarean section if she and the fetus are not stable

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: · frequent blood counts, or CBCs · blood tests to monitor the ability of her blood to clot · vital signs

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.

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