Placenta percreta is a condition where the placenta penetrates the uterine wall and attaches itself to the urinary bladder or rectum. Placenta percreta, placenta accreta, and placenta increta are diagnosed by how deep the placenta penetrates the uterine wall. The placenta usually has a cleavage plane where it automatically detaches itself from the uterus after birth. In placenta accreta along with placenta percreta, and increta, the cleavage plane does not exist. In placenta accreta, the placenta does not invade the myometrium (uterine muscle). Placenta increta occurs when the placenta invades partially into the uterine muscle, while placenta percreta invades the width of the myometrium and sometimes invades surrounding anatomical structures.
Luckily, placenta accreta, increta, and percreta are rare. The occurrence of these placental abnormalities are roughly one out of five hundred pregnancies. Some estimates place them as low as one out of 2500 pregnancies. Placenta percreta is the rarest of the three placental abnormalities.
Certain conditions such as cigarette smoking, a previous cesarean section, having had a previous pregnancy, currently having a placenta previa, maternal age greater than or equal to 35 years, a previous dilation and curettage (D&C), or having been treated for Asherman’s Syndrome place a patient at risk for placenta percreta. Briefly, Asherman’s Syndrome is a condition where the patient underwent a vigorous D&C, and the endometrium (lining of the uterus) was denuded producing scarring of the uterus. The most common clinical presentation of Asherman’s Syndrome is absent menses following a D&C.
The diagnosis of placenta percreta is usually made on ultrasound and/or MRI (Magnetic Resonance Imaging). Both of these studies are do not harm the fetus.
Often, there is third trimester vaginal bleeding which causes the provider to order imaging studies and lab work to find the cause of the bleeding. Upon making the diagnosis of placenta percreta, your provider will most likely recommend a transfer to a tertiary care center as the delivery and prenatal care will be complicated. Placenta percreta increases the risk of spontaneous abortion (miscarriage), preterm delivery, postpartum bleeding, and birth defects.
Vaginal bleeding during pregnancy can sometimes produce uterine irritability or contractions. Often, the vaginal bleeding and the uterine contractions can set up a vicious cycle where the more you bleed, the more you contract, which in turn causes more vaginal bleeding. Your provider may choose to place you on magnesium sulfate to diminish the contractions, and interrupt this cycle. In addition, your provider may recommend betamethasone (a steroid which is administered to the mother via intramuscular injection) to accelerate the fetal lung maturity. In most cases, the infant will be delivered early by planned cesarean section somewhere between 34 to 38 weeks gestation.
The provider will attempt to delay the delivery as long as clinically prudent (34-38 wks). He will follow you with serial nonstress tests (NSTs) where a belt is placed around the maternal abdomen, and the fetal heart pattern is observed on the fetal monitor. A reactive, or reassuring, fetal heart pattern will allow you to continue with the pregnancy. A nonreactive nonstress test may force your provider to deliver the infant on the day of the nonreactive NST. He will also order serial biophysical profiles (BPPs) where an ultrasound is done and the fetal well being is evaluated by ultrasound looking at fetal movement, quantity of amniotic fluid, fetal flexion, and fetal breathing. The BPP combined with the NST will give your provider a good idea of how the fetus is doing. If the BPP is encouraging, your provider may elect to continue with the pregnancy in spite of the nonreactive NST.
As mentioned previously, the delivery will be accomplished via cesarean section, and there is a high probability that a hysterectomy will be performed after the infant is delivered as there will be heavy postpartum bleeding due to the attached placenta. This is a serious, life threatening condition. The mortality rate to the mother is around 9.5% while the mortality rate for the infant is about 24%.
The delivery will be accomplished by a team of surgeons including the obstetrician, urologist, general surgeon, gynecologic oncologist, and an interventional radiologist. The composition of the team may vary depending on the case and the hospital. There have been attempts to deal with this condition without having to perform a hysterectomy, but the results are disappointing. The recommended procedure following the cesarean section remains the hysterectomy.
As I mentioned previously, this is a rare occurrence. Wishing you a successful and problem free delivery. Pablo