Let’s Talk Placenta Previa

Discovery Health defines placenta previa as: “A condition in which the placenta partially or completely covers the cervix, hindering vaginal delivery”. Erin and The Beanlet share this condition, which (according to only 1 study) happens in around 6 of every 1,000 pregnancies, and is 14% more likely to happen with a male fetus [source].

Now, if you decide to do your own research on the Internet about previa, you’ll find a ton of really scary information. So, consider this a primer.

Disclaimer: I’m not a doctor. I have a degree in biology, and took an embryology course in college. How does that qualify me to speak of such things? It doesn’t. All of the images here are highly simplified, and were created by me to highlight only the most important point of this discussion: the position of the placenta relative to the other major structures involved (the uterine wall and cervix). None of this information should be considered professional advice or anything close to replacing consultation with an obstetrician.

Here’s a representation of “normal” placental placement. Take note of the labels identifying the major structures, as they will be omitted in following images. The black X in each diagram represents the point where the center of the placenta embeds in the uterine wall.

The placenta will be called “low-lying” if it is positioned such that its edge lies within a few centimeters of the cervical opening.

Marginal placenta previa is diagnosed when the edge of the placenta contacts the opening in the cervix. Note the arrow.

Complete placenta previa happens when the placenta covers the entire cervical opening. The following image represents the worst-case scenario. The majority of the images available on the Internet show this type of previa, and never hint that center of the placenta could be positioned anywhere but directly over the center of the cervix. This is the Chicken Little “the sky is falling” diagram.

Here’s what’s going on with The Beanlet:

Doesn’t look as bad as Chicken Little up there, does it?

For now, Erin’s doctor is being extremely cautious, and has her–effectively–on bed-rest. Any flexing of the cervix could result in a minor tear of the overlying placenta (which is packed with blood vessels), and cause bleeding. That is never a good thing.

When speaking (or reading) of previa, there’s invariably a comment about the placenta “moving out of the way” or “migrating” so it no longer covers the cervical opening. Erin’s doctor described it like this: Imagine drawing an X near the opening of an empty balloon. Then blow up the balloon, and notice how the distance between the X and the opening increases, but the X doesn’t actually change position on the balloon’s surface. This is the reason for the Xs on these diagrams. Theoretically (Erin’s doctor says it happens in about 70% of her cases), The Beanlet’s placenta could “migrate”:

In the above diagram, the position of the X on the internal surface of the uterus does not change, yet the edge of the placenta clears the cervical opening (arrow) as the uterus grows larger. There is no guarantee that this will happen.

Erin has another sonogram scheduled for August 11th. If the placenta clears the cervical opening, then the aforementioned chance of bleeding is greatly reduced, and she can go back to having a “normal” pregnancy.

As Erin’s pregnancy progresses, her delivery options will become clearer. The “official” due date is November 5th or 6th, but if the previa dictates a cesarian, that will happen sometime in mid-October. We’ll keep you posted.