Week 5: Placenta Previa

I'm going to try and make this post short and to-the-point because I have a LOT of school to do...

Last week in class, we learned about placenta previa. It has the potential of being fatal to mom and/or baby and occurs in 1 in 200 term pregnancies.

Placenta previa is classified by painless vaginal bleeding. It is when the placenta covers all or part of the cervix. When the cervix starts to dilate and thin, it breaks the blood vessels in the placenta which causes a hemorrhage. The hemorrhage can sometimes be small and controllable and the pregnancy can be continued under close supervision. However, it can also cause massive hemorrhaging, lack of oxygen to the baby, and death for both mom and/or baby. Usually, it is somewhere in the middle, but if a pregnant woman ever experiences a lot of painless vaginal bleeding (more than just the normal spotting that occurs with labor), she should call her midwife/doctor immediately and be evaluated.

Normally, the placenta is near the top of the uterus. Sometimes, it will implant close to the cervix (called a low-lying placenta) but as the uterus grows throughout pregnancy, the placenta will "migrate" up the side of the uterus.

Placenta previa can either be classified as a low-lying placenta, marginal placenta previa, or complete placenta previa.

Low-lying placenta is exactly as its name implies. It's a placenta that is really low in the uterus and might be partially touching the cervix. It can cause some vaginal bleeding as the cervix stretches and thins, but is usually harmless.

Marginal placenta previa is sometimes manageable too but the edge of the placenta is covering part of the cervix. This usually requires a Cesarean delivery since the baby can't exactly be born when half his exit route is covered...

Complete placenta previa is where the placenta completely covers the cervix. This requires a Cesarean section birth since there is absolutely no way the baby can be born when his exit route is completely covered. Also, the Cesarean is usually planned in advanced and before the mom goes into labor since when the cervix dilates, it breaks the blood vessels to the placenta causing massive hemorrhage and lack of blood going to the baby. Yah, it has the potential to be very bad.

When placenta previa is present, the baby has a fairly high chance of being breech because the placenta blocks his usual head spot. This is illustrated in this picture:

So anyway, that's the down and dirty on placenta previa. :-D