What
are the different types of placenta previa?
Complete previa - The placenta completely covers the cervix.
Partial
previa - The placenta covers a portion of the cervix, but
does not completely cover the cervix.
Marginal
previa - The placenta extends to the edge of the cervix but
does not cover it. This can also be called low placental implantation.
What
is the cause of placenta previa?
The cause of placenta previa is unknown.
Am
I at risk for placenta previa?
Placenta previa occurs in about 1 in 200 births. Risk factors
include:
- previous
history of placenta previa
- twins,
triplets, or higher multiple
births
- having
given birth before (second or greater pregnancy)
- smoking
- over
the age of 35
- surgery
of the uterus
- prior
delivery of a baby via cesarean section
- history
of uterine abnormalities
Symptoms
of placenta previa
Vaginal bleeding after 20 weeks of pregnancy is the primary
symptom of placenta previa. Bleeding
during pregnancy
may have another cause, however, it is important to call your
doctor if you experience bleeding.
The
placenta normally attaches to the upper portion of the uterus
which is more muscular and stronger to support the placenta.
However, in placenta previa the placenta attaches to the lower
portion of the uterus which is weaker, thinner, and more vascular.
As you enter your second and third trimester, the cervix begins
to thin and stretch in preparation for labor. As this area
stretches it can cause the villi (blood vessels) to break
therefore causing bleeding. Placenta previa can lead to complications
for both mother and baby. Complications that may arise include
placenta abruption, hemorrhaging, preterm
labor,
anemia for either mother or baby.
Treatment
of placenta previa
Placenta previa will often correct itself during pregnancy.
In more than 90 percent of women diagnosed with placenta previa
in the second trimester, the placenta will correct itself
by the end of the pregnancy. The placenta itself doesn't actually
move, but as the uterus stretches it is not as close to the
cervix as it was earlier in pregnancy. Think of it this way,
imagine taking a balloon and drawing a circle on it at the
lower end of the balloon. Then blow up your balloon. The circle
doesn't actually move, but it may not still be at the lower
end once it has completed stretching. So for the majority
of women, placenta previa will correct itself.
If
placenta previa, however, does not correct itself there are
several things that can be done to manage it. Placenta previa
will usually require bedrest and frequent visits to your doctor
or hospital. Vaginal exams are not recommended for the pregnant
woman with placenta previa. You may be given steroid shots
to mature your baby's lungs because you at risk for delivering
early. Treatment will vary depending on how far along you
are in your pregnancy and whether you have complete, partial,
or marginal placenta previa. If you start bleeding or having
contractions, you will be hospitalized. Your doctor will want
to monitor you baby's heart rate and monitor your vital signs
as well. If bleeding stops, your doctor may send you home
on bedrest. If bleeding cannot be controlled an immediate
cesarean section is given regardless of length of gestation.
If bleeding is controlled your doctor will discuss scheduling
a cesarean section with you. In most cases of placenta previa
that does not correct itself, a cesarean section is necessary
due to the location of the placenta.
Complications
after delivery
Because
the risk of hemorrhaging is higher for women with placenta
previa, mothers will be monitored for signs of hemorrhaging.
She may be given medications to control bleeding such as pitocin
and a transfusion may sometimes be necessary. Anemia may occur
in mother or baby therefore hemoglobin levels will be monitored
and iron supplements may be given.
