The placenta usually separates easily from the uterine wall once the infant is delivered. There are exceptions to this, and those exceptions are known as placenta accrete, increta, and percreta. Placenta accreta attaches itself to the myometrium (uterine muscle), but does not penetrate into the muscle itself. Placenta increta invades partially into the myometrium, but not completely through the uterine muscle. Placenta percreta invades the full thickness of the myometrium, and sometimes invades into the surrounding anatomical structures like the urinary bladder and the rectum.
The exact cause of placenta increta is unknown, but has a higher incidence of occurrence in placenta previa. Placenta previa is a condition where the placenta covers the opening of the cervix either completely or partially, and this condition requires a cesarean section for delivery. The rising cesarean section rates have also caused a rise in placenta increta along with placenta accreta and percreta.
All three abnormal placental conditions have an increased risk of preterm delivery with the accompanying morbidity and mortality for the infant. A diagnosis of placenta increta can be made on ultrasound, but not always. Sometimes, the diagnosis is made or suspected when bleeding occurs in the third trimester of pregnancy. If this diagnosis is made on ultrasound, your provider will inform you of the findings and arrange for close follow up during your pregnancy. Your provider may also arrange for a transfer to a tertiary care center for your delivery.
The biggest risk to the mother is hemorrhage following the delivery as the placenta will not detach itself from the myometrium. In order to avoid the life threatening emergency that can arise from the attached placenta, the standard procedure is to schedule a cesarean section around 34-36 weeks followed by a hysterectomy at that time. The placenta will be left attached to the uterus after the delivery to minimize bleeding. There will, most likely, be a team of physicians present at the time of delivery including the obstetrician, a general surgeon, urologist, and interventional radiologist along with the pediatrician or neonatologist.
Depending on how your pregnancy is progressing, your provider may elect to hospitalize you until the time of the scheduled cesarean section. During the prenatal course, your provider will most likely administer a steroid, betamethasone, to accelerate the fetal lung maturity. In addition, the provider will want to follow the fetal well being by performing nonstress tests (NSTs) on a weekly or twice a week basis. Biophysical profiles (BPPs) will be done once a week. A biophysical profile is a special type of ultrasound that looks at the amount of amniotic fluid, fetal movement, whether the fetal limbs are flexed or extended, and fetal breathing. This will provide a score which will then let your provider know the well being of the fetus. The highest individual score for each finding on the BPP is 2. A score of 10/10 is optimal, and this score includes the NST which is also given a value of 2. Values of 0 and 1 are also possible, but less desirable.
You will be asked to monitor the infant’s movements by keeping track of the kick counts. You should contact your provider immediately if there is a decrease in fetal movement. If you are allowed to stay at home, you will be asked to follow a regimen of bed rest and pelvic rest. Any vaginal bleeding is to be reported immediately.
Wishing you a happy and problem free delivery, Pablo.