September 17, 2011

A miscarriage is a pregnancy that ends before the fetus reaches a point where it would be able to survive outside the uterus. The medical term for a miscarriage is a “spontaneous abortion.” About 80% of miscarriages occur in the first trimester, meaning the first 12 weeks of pregnancy. Approximately 20% of pregnancies end in miscarriage. There are probably another 10% of pregnancies lost before women actually realize they are even pregnant.

When a miscarriage occurs, couples are very anxious to understand why this event, which can be devastating, has happened. Approximately 50% of miscarriages are due to genetic abnormalities of the fetus. Most babies are born perfect, and this is “nature’s way” of controlling this wonderful phenomenon. Most abnormal fetuses will not continue to grow and will result in miscarriage. The earlier in a pregnancy a miscarriage occurs, the more likely that it was a result of a genetic abnormality. Miscarriages may also be the result of uterine abnormalities such as fibroids or cervical abnormalities. Women with repeated pregnancy losses may require complex evaluations looking for possible autoimmune or endocrine diseases. Miscarriages are not caused by maternal activity (exercise, heavy lifting, etc.) or intercourse. Often patients are concerned about how they may have contributed to this event. It is important to discuss these concerns with your physician. It is unusual to know why a miscarriage occurred.

There are multiple factors that increase the risk of a miscarriage. The most important of these is maternal age. Between the ages of 20 and 30, the risk of miscarriage is 9-17%. At age 35, the risk is 20%, at age 40, the risk is 40%, and at age 45, the risk is 80%. The risk of miscarriage also increases with the more children a woman has had, this is independent of her age. Having had a previous miscarriage is a risk as well. But this is very much dependent on how many miscarriages have occurred. After a single miscarriage, the risk of a second is about 20%, after two miscarriages, the risk is about 28%, and after three miscarriages, the risk is 43%. Most physicians begin an investigation as to why a miscarriage occurs after two or three miscarriages; this will depend upon the patient’s specific situation. Smoking and alcohol consumption also increase the risk. Caffeine increases the risk at a significant level when 4-5 cups or more of coffee are consumed a day. There are also, less commonly, risks from maternal exposure to chemicals, medications, or infections.

There are many ways in which a woman may learn that she has had a miscarriage. The most common way is by vaginal bleeding and/or abdominal cramping. These symptoms may also occur, however, in a normal pregnancy or an ectopic pregnancy (pregnancy outside of the uterus). Because of this, ultrasound is key to the evaluation of a possible miscarriage. If a heartbeat is not seen by approximately 6 weeks gestation (6 weeks from the last menstrual period) on a transvaginal ultrasound (specialized procedure using sound waves to visualize the structure around and in the uterus), concern of miscarriage increases. When the diagnosis is not entirely clear, blood levels of the pregnancy hormone, beta-HCG, may be followed over the course of several days. If vaginal bleeding is heavy and the cervix has already begun to dilate, the miscarriage is considered “inevitable.” If bleeding is occurring in the face of a heartbeat on ultrasound and a closed cervix, the miscarriage is considered “threatened”; this can be an extremely stressful time for a woman. Continued surveillance with ultrasound is then indicated. There are times when bleeding has occurred to the point that the fetus is passed as well. In these cases an ultrasound reveals an empty uterus. This is called a “complete abortion” and usually no further medical or surgical treatment is necessary. If a significant amount of tissue remains in the uterus, despite loss of a fetal heartbeat, this is called an “incomplete abortion” and often the patient is offered medical or more commonly surgical therapy to complete the miscarriage and clear the uterine cavity. Because of the frequent use of early ultrasound, often a miscarriage is diagnosed even before the patient has experienced any vaginal bleeding. In this case, a routine ultrasound would reveal that the fetus is either not developing normally or no longer has a heartbeat.

Treatment of a miscarriage is varied. If a pregnancy is before approximately 7-8 weeks, often a woman is encouraged to “let nature take its course.” In other words, no intervention would be made by the physician and the woman would simply wait to see whether the pregnancy passes on its own. Usually this occurs within 2 weeks, but may take longer. This can result in heavy bleeding and painful cramping, but can be handled well by most women. If at any time the woman felt the bleeding was too heavy or pain too severe, she would contact her physician. In order to expedite passing the pregnancy, or to attempt this later in the first trimester, medication may be considered. More commonly, however, a woman is offered a dilation and curettage (D&C) to complete the miscarriage. This is a surgical procedure done either in the operating room or in the physician’s office. This is a decision made by the woman and her physician. The risks of D&C are small, but include bleeding, infection, and uterine perforation.

After a miscarriage, it is usually advised not to have intercourse until after the next normal menses. If intercourse occurs before then, a condom should be used. It is medically safe to attempt pregnancy again after the first normal menses. Many couples are encouraged to wait 2-3 cycles, however, to give themselves some time to heal psychologically from this emotionally difficult event. If a woman feels she is more depressed than she would expect, or is concerned about her mood in any way, it is very important for her to discuss this with her physician.

SEE ALSO: Autoimmune disorders, Ectopic pregnancy, Genetic counseling, Pelvic organ prolapse, Pregnancy, Uterine fibroids


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