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Placenta Problems During Pregnancy
Placenta accreta is a rare condition that occurs when the placenta attaches itself too firmly to the wall of the uterus and cannot be removed after birth. Heavy bleeding often occurs after the delivery of the baby, and the usual treatment is removal of the uterus (a hysterectomy) as an emergency procedure.
Normally the placenta attaches to the front, back or side of the uterus, but if it attaches to the lower part, it may cover the opening of the uterus, through the cervix to the outside. This is placenta praevia. It is more common in women who have had several pregnancies, and it occurs in one in every 150 pregnancies.
In the later stages of pregnancy, the cervix starts to dilate to allow the head of the baby to drop, prior to labor starting. If the placenta is over the opening, it will be damaged by the dilation of the cervix and the pressure from the baby's head, and heavy bleeding may occur suddenly.
Placenta praevia may be suspected by the presence of a baby that is unusually high in the womb, and the position of the placenta can be seen accurately on an ultrasound scan. When diagnosed, the mother will be watched carefully, often in hospital, and about a month before the due date, a cesarean section will be performed to remove both baby and placenta safely.
A bleeding placenta praevia can be a medical emergency, as quite torrential bleeding can occur which may threaten the lives of both mother and baby. The only treatment is an urgent cesarean section.
Placental abruption is the term used for a partial separation of one portion of the placenta from the wall of the uterus. It usually causes some vaginal bleeding, but usually no pain. Abruption may be caused by high blood pressure in the mother, or injury to the mother, but in the vast majority of cases, no specific cause can be found. Mild cases cause no long-term problems, but if a large portion of the placenta separates from the uterus, the blood supply to the fetus may be reduced and cause reduced growth or, in severe cases, death of the fetus.
No treatment is available or necessary in most cases, but if there is significant bleeding, the mother may need a transfusion. In the rare cases where the fetus dies, an operation to remove it is necessary.
After the delivery of the baby, the placenta normally separates away from the wall of the uterus and is expelled by the contractions of the uterus within a few minutes. The process may be assisted by a doctor using injections to improve the uterine contractions and maneuvers to assist the separation of the placenta. If it fails to separate from the uterus and remains retained within the uterus, it is necessary to perform a simple procedure to remove the retained placenta. Without this procedure, the mother would continue to bleed, and this could threaten her life.
Under a general anesthetic, the doctor slides his hand into the uterus, and uses his fingers to separate the placenta from the uterus and lift it away from the wall of the uterus, so that it can be drawn to the outside of the body through the vagina.