A miscarriage refers to the spontaneous expulsion of the fetus from the uterus before the fetus can survive on its own. Up to 15% of all pregnancies and approximately 30% of first pregnancies end in miscarriage. At least 75% of miscarriages occur during the first trimester.
What causes it?
Miscarriage may result from fetal, placental, or maternal factors. Petal factors, which usually cause miscarriage at 9 to 12 weeks' gestation, include defective development of the embryo due to abnormal chromosome division (most common cause of fetal death), faulty implantation of the fertilized ovum (egg), and failure of the endometrium to accept the fertilized ovum.
Placental factors usually cause miscarriage around the 14th week, when the placenta takes over the hormone production necessary to maintain the pregnancy. These factors include premature separation of the normally implanted placenta and abnormal placental implantation.
Maternal factors, which usually cause miscarriage between the 11th and 19th weeks, include a long list:
• maternal infection, severe malnutrition, drug ingestion, abnormalities of the reproductive organs (especially an incompetent cervix, in which the cervix dilates painlessly and bloodlessly in the second trimester)
• endocrine problems, such as a thyroid disorder
• trauma, including surgery involving the pelvic organs
• certain immune disorders or blood group incompatibility.
What are its symptoms?
Signs of an impending miscarriage may include a pink discharge for several days or a scant brown discharge for several weeks before the onset of cramps and increased vaginal bleeding. For a few hours, the cramps intensifY and occur more frequently; then the cervix dilates to expel uterine contents. If expulsion is complete, cramps and bleeding subside. However, if any contents remain, cramps and bleeding continue.
How is it diagnosed?
Diagnosis of miscarriage is based on clinical evidence of expulsion of uterine contents, a pelvic exam, and lab studies. Decreased levels of human chorionic gonadotropin, a hormone that is present in the blood or urine during pregnancy, suggest miscarriage. A pelvic exam determines the size of the uterus and whether this size is consistent with the length of the pregnancy. Microscopic exam reveals evidence of products of conception. Lab tests reflect decreased hematocrit and hemoglobin levels due to blood loss.
How is it treated?
Uterine contents must be carefully examined before a treatment plan can be formulated. A miscarriage can't be prevented, except when the cause is an incompetent cervix. If bleeding is severe, the woman must be hospitalized and receive a blood transfusion. Initially, intravenous Pitocin stimulates uterine contractions. If any remnants remain in the uterus, dilatation and curettage or dilatation and evacuation should be performed.
A woman who's had several miscarriages because of an incompetent cervix may have it surgically reinforced 14 to 16 weeks after the last menstrual period. A few weeks before the estimated delivery date, the sutures are removed and the woman awaits the onset of labor, An alternative procedure, especially for a woman who wants to have more children, is to leave the sutures in place and to deliver the infant by cesarean section.