Placenta Previa 

After I finished my shift at The Valley Hospital as the "Doc in Box" I did my rounds and went home. My shift ended at 7 am. I signed out and handed the phone over to the next on call Obstetrician, and came home around 8:30 AM or so. Then I tried to get some sleep. I did some reading, and finally did fall asleep. 

Later in the morning I got a phone call. 

I have a full term pregnant patient who has a suspected placenta previa. What does that mean? 

A human embryo is created about day 14 of a 28 day cycle. This is called ovulation. Once the egg pops out of the ovary on day 14, the sperm will start looking for it. If there are sperm there, they will all swim to the egg. The egg is surrounded by a protective covering called the zona pellucida. One sperm by itself is unlikely to get through the zona. Instead, about a hundred sperm need to be there. But usually only one sperm will penetrate the egg membrane. This process is called fertilization.  The egg once fertilized becomes an embryo and starts floating down the Fallopian tube. A week after fertilization, about day 21 of a normal 28 day cycle, the embryo will float (or be propelled by tubal peristalsis) into the uterus. By day 21 the uterine wall is covered with a sticky secretion that is ready for the embryo to come along.  The embryo floats around until it comes into contact with the uterine wall. Once it does, it sticks on, and starts to burrow into the uterine wall. This will frequently cause a day 23 spot of blood called an implantation bleeding. Any women who is trying to get pregnant should welcome the day 23 spot of blood. It is really great news. The problem with implantation is that it can happen almost anywhere. Ideally it can happen in the fundus, or body, of the uterus. Sometimes the embryo implants in the fallopian tube. This is called an ectopic pregnancy and may be a life threatening emergency. Sometimes the embryo is just a few millimeters short of making it into the uterine cavity. This is an even worse spot called a cornual ectopic. This means the implantation is in the "corner" of the uterus, in the part of the fallopian tube that is within the muscle of the uterus. Nowadays, some ectopics can be treated with cancer chemotherapy, and therefore avoid surgery. Obviously there are risks with chemotherapy as well. And sometimes the ectopic can take forever to dissolve. But is is there as an option. 

But for a placenta previa, the implantation occurs very low in the uterus. It is then very near the cervical opening. When this happens the placenta grows very low. The placenta itself grows over the cervical opening. Since the baby needs to come out the cervical opening, and the placenta is in the way, there will be a life threatening hemorrhage when the women goes into labor. The baby will not survive losing the placenta's function while still inside the mother. When the placenta disconnects from the mother, there will be a hemorrhage, and the baby will suffocate from lack of oxygen. 

There are many different types of previa. If the baby implants in the cervix, instead of in the uterus, it is called a cervical ectopic. This is a bad event that needs to be managed quite urgently. 

If the placenta only edges up to the cervix, it will be called a marginal previa. This can go either way. If the placenta is low, but not up to the cervix, it will be called a low placenta. These women can try for a vaginal birth if they want, but they are subject to abnormal bleeding. If they bleed a lot in labor, then a C-Section might be safer. 

My patient today was told she had a previa early on in the pregnancy. We watched  the baby and the placenta very carefully for many months. The placenta seemed to move away from the cervix a bit as the uterus grew up to full term size. This is not unusual. Many previas resolve themselves as the pregnancy grows. We had at first scheduled her C-Section, but then unscheduled it because the placenta appeared to be in a better spot. 

As a pregnancy grows, the uterus grows with the baby. The uterus and the baby grow about a centimeter a week. The placenta, if it is stuck sufficiently to the uterine wall, can move up with the uterine growth. But, on the other hand, the placenta and the baby are growing. The placenta, if it is stuck near the cervix but continues to grow, it can grow back over the cervix. This can make a marginal previa worse, so that it can become a total previa again. 

So, it is best to follow the previa clinically. Analyze its growth pattern. Follow it with the sonogram. Try to make predictions about what might happen with time. Don't examine it with the hands, because that may cause severe bleeding. Only examine it with the sonogram. And if there is a lot of bleeding, then deliver the baby by C-Section. The delivery can be elective at term, or at any time if there is a lot of labor contractions or bleeding. 

But today, she was 39 weeks and waiting for labor, when she started having a bloody show. The bloody show was normal, and a good sign that labor might be beginning. But then she broke her water, and the water gushed out and was very bloody. She called and I advised her to go to the hospital. At the hospital she kept on bleeding and ultimately passed a softball sized clot. Obviously this is risky for both the baby and the mom, so I advised a Cesarean after all. She couldn't keep bleeding to that extent and expect a happy outcome. So we did it. And everybody is fine now. At the C-Section we did find that the previa was close to or over the cervix, so labor would have continued to be very risky, and the bleeding would have gotten much worse with time. 

She didn't get her vaginal birth. But she did get a healthy baby at 39 weeks. Everybody is fine. Maybe the next baby can be a vaginal birth if she wants to try for it, and there is no previa. We will have the discussion about the benefits and the risks of a VBAC. VBAC means vaginal birth after Cesarean Section. 

Thank you all for reading today's blog. I appreciate all of the readers from around the world. 

Sincerely, 

John Marcus MD Ob/Gyn FACOG

89 North Maple Ave

Ridgewood, NJ, 07450 

201-447-0077