Placenta Previa

What is a placenta previa?
A placenta previa is a placenta that is implanted at or close to the internal os (mouth) of the cervix.
 Placenta previa happens in about 1 in 200 pregnancies, though the incidence has increased over the last years because certain risk factors such as prior cesarean sections have increased.

Placenta previa can be dangerous because women with this condition are more likely to bleed, deliver early, and have a condition called "placenta accreta of just placenta creta".

There are several kinds of placenta previa depending on how close they are to the internal os of the cervix:

1. Total placenta previa occurs when the internal cervical os is completely covered by the placenta.
2. Partial placenta previa occurs when the internal os is partially covered by the placenta.
3. Marginal placenta previa occurs when the placenta is at the margin of the internal os.
4. Low-lying placenta previa occurs when the placenta is implanted in the lower uterine segment. In this variation, the edge of the placenta is near the internal os but does not reach it.

Who is at increased risk for a placenta previa?
The following are increased risk factors for a placenta previa:
    1.    Prior uterine surgery
    2.    Prior cesarean sections
    3.    Prior placenta previa
    4.    Multiples (Twins, triplets)
    5.    Previous deliveries

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