Attached placenta is a rare complication, but the condition can lead to life-threatening bleeding associated with childbirth. The risk of sitting placenta is higher in women who have previously undergone caesarean section.
What is placenta accreta?
In a normal pregnancy, the fertilized egg attaches to the thick and nutritious mucosa inside the uterus. The placenta is formed and grows in this mucosa. At birth, the mucous membrane and the placenta release, and the placenta comes out as a unit. In placental accreta, parts of the placenta grow through the mucous membrane and into the uterine wall, partially attaching to the muscle wall. At birth, the placenta is left hanging on these attachments to the muscle.
Placental accreta is a rare complication, but as the use of cesarean section increases, so does the incidence of placental accreta. In the United States, it is estimated that this diagnosis is proven in 1 per 500 to 1 per 2,500 births, and this is more than 10 times more common than 50 years ago.
All details of why the placenta sometimes grows and attaches too deeply are not known. But it is known that it often happens if the mucous membrane of the uterus is damaged, or is too thin. This is evident from the fact that placental accreta is first and foremost found in women who have scarring in the uterus, and previous cesarean sections are the dominant cause of scarring in the uterus. At the bottom of the uterus, the uterine mucosa is slightly thinner than in the middle parts, and therefore low lying placenta also carries an increased risk. In addition, the risk increases slightly among women who smoke, who have given birth to many children, and with increasing age in the woman.
During pregnancy, in most cases, the pregnant woman has no symptoms or symptoms as a result of a stuck placenta. Shortly after birth, the placenta should normally come loose and come out. When the placenta does not come off, this often leads to severe and persistent bleeding. This can be a life-threatening situation, but in hospitals with access to blood transfusions and intensive care, things usually go well.
Placental accreta is increasingly being found in connection with ultrasound examination. If there is a suspicion of this diagnosis in the case of normal external ultrasound, an internal ultrasound (via the vagina) may provide a more reliable diagnosis. But research suggests that it is not possible to detect all cases of ultrasound, and therefore one must be prepared for this diagnosis at birth.
A seated placenta and heavy bleeding motivate emergency surgery. Caesarean sections are performed and the doctors will try to release the placenta from the uterine wall. In many cases this is not possible, and then both the uterus and the placenta must be removed during surgery. If the diagnosis is made in advance, the procedure is planned and performed well in advance of the delivery. You then first remove the baby with a normal caesarean section, and then remove the placenta or the entire uterus with the placenta in place, during the same procedure.
In cases where the diagnosis is made shortly after birth, you will not usually be able to surgically remove the uterus to control the bleeding.
Because undergoing caesarean section is a predisposing factor for placental accreta, this is one of many arguments for not performing cesarean unless it is medically necessary.