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McKesson Clinical Reference Systems: Women's Health Advisor 2002.2
Illustration
Placenta Previa
What is placenta previa?
Placenta previa is a condition in pregnancy in which the
placenta lies below the baby in the uterus. It may
partially or completely cover the opening of the uterus
(cervix).
The placenta develops in the uterus during pregnancy and
allows oxygen, nourishment, and wastes to pass between the
mother and the baby.
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,
the doctor may have to deliver the baby early 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 a cesarean section
- have had placenta previa before.
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
labor, 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 done are:
- ultrasound scan to see where the placenta is attached in
the uterus
- blood tests
- double setup exams if there is no time for an ultrasound
or ultrasound is not available (A double setup exam is an
exam of the cervix with a speculum in the operating
room. Your doctor will be ready to do a cesarean section
if necessary.).
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.
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 the
doctor 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.
How can I take care of myself?
Report any bleeding to your doctor. To prevent bleeding,
limit your regular activity or 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.
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