The placenta is a flat, spongy structure that grows inside the mother's uterus. It is attached to the fetus by the umbilical cord and carries nourishment and oxygen from the mother to the baby. It also carries waste products from the baby to the mother for excretion. Problems with the placenta sometimes occur, and they are discussed below.
With placenta previa, the placenta covers part or all of the cervix. When the cervix begins to open (dilate), the placenta tears away from the cervix as it opens, causing heavy bleeding. An emergency C-section is likely to follow. Heavy bleeding can be dangerous for the mother-to-be and the baby.
The most characteristic symptom of placenta previa is painless bleeding. Your doctor will order an ultrasound exam if you have not already had one to determine the location of the placenta. He or she will not do a pelvic exam because it may cause heavier bleeding. If you see a different doctor or when you go to the hospital, tell whoever examines you that you have placenta previa and should not have a pelvic exam.
Most physicians recommend avoiding intercourse, not traveling and not having a pelvic exam if you have placenta previa.
The baby is more likely to be in a breech position. For this reason, and also to avoid bleeding, a C-section is almost always performed.
Placenta previa occurs in about 1 birth in 200.
Placental abruption is separation of the placenta from the wall of the uterus during pregnancy. Normally the placenta does not separate until after delivery of the baby. When the placenta separates before birth, it can be very serious for the baby.
The cause of placental abruption is unknown; however, certain conditions may make it more likely to occur. These include:
|trauma to the mother, such as from a fall or a car accident|
|an umbilical cord that is too short|
|very sudden change in the size of the uterus, as in the case of the rupture of membranes|
|an abnormality of the uterus, such as a band of tissue in the uterus called a uterine septum|
Signs and symptoms include:
|heavy bleeding from the vagina|
Placental abruption may occur without the presence of any or all these symptoms. Ultrasound may be helpful to diagnose placental abruption, but it does not always provide an exact diagnosis.
Risks to the mother-to-be include shock, severe blood loss and the inability of the blood to clot.
The most common treatment is delivery of the baby. However, the decision of when to deliver the baby varies, depending on the severity of the problem.
In some situations, if the baby needs to be delivered rapidly, you will need a Cesarean section. That decision is made on an individual basis.
The frequency of placental abruption is estimated to be about 1 in every 80 deliveries.
We now believe folic-acid deficiency may play a role in causing placental abruption. Extra folic acid may be prescribed during pregnancy. Maternal smoking and alcohol use may make it more likely for a woman to have placental abruption. If you smoke or drink alcohol, you may be advised to stop both activities.
A retained placenta is a placenta or placental tissue that does not deliver following the birth. Usually the placenta separates on its own from the uterus a few minutes after delivery. In some cases, it doesn't separate because it is attached to the wall of the uterus. This can be very serious and can cause extreme blood loss.
Reasons for a retained placenta include a placenta attaching •over a previous C-section scar or other incision scar on the uterus •in a place that has been curetted (scraped), such as for a D&C •over an area of the uterus that was infected
The most significant problem caused by a retained placenta is heavy bleeding after delivery. If the placenta is not delivered, it must be removed some other way. One solution is to perform a D&C. However, if the placenta has grown into the wall of the uterus, it may be necessary to remove the uterus by performing a hysterectomy.
A retained placenta occurs in about 1% of all deliveries.