Miscarriage

INTRODUCTION — A miscarriage is a pregnancy that ends before the fetus is able to live outside the uterus. A brief review of the events of early pregnancy will help in the understanding of miscarriage.

A woman's reproductive system includes the uterus (including the cervix), two ovaries, two fallopian tubes, and the vagina. The fallopian tubes are a pair of hollowed tubes that run from each side of the uterus to the ovaries (show figure 1). Once a month, an egg is released by one of the ovaries and travels down the fallopian tube. If the egg is fertilized in the tube by the male's sperm, pregnancy begins.

Once the egg and sperm join, they rapidly develop new cells. This bundle of cells, called the embryo, normally implants on the inner wall of the uterus. Once implanted, the embryo continues to grow inside a sac of amniotic fluid, sometimes called the "bag of water." After several weeks, the embryo is called a fetus.

INCIDENCE — Miscarriage in early pregnancy is very common. Studies show that about 10 to 20 percent of women who know they are pregnant have a miscarriage some time before 20 weeks of pregnancy; 80 percent of these occur in the first 12 weeks. But the actual rate of miscarriage is even higher since many women have very early miscarriages without ever realizing that they are pregnant. One study that followed women's hormone levels every day in order to detect very early pregnancy found a total pregnancy loss rate of 31 percent.

CAUSES — Many different factors can lead to miscarriage, and it is difficult to say with certainty what causes a particular miscarriage to occur. One or more problems with the pregnancy can be found in a significant percentage of early miscarriages.

As an example, in 1/3 of miscarriages occurring before 8 weeks, there is a pregnancy sac but no embryo inside. This means the egg was fertilized and the cells began to divide, but an embryo did not develop. In other cases, the embryo develops but it is abnormal. Chromosomal abnormalities, in particular, are common. One study found that of 8841 miscarriages, 41 percent had chromosomal abnormalities.

In some cases, medical conditions in the mother, such as uncontrolled diabetes, or structural problems in the reproductive tract, such as uterine fibroids, can lead to miscarriage. (See "Patient information: Care during pregnancy for women with type 1 or 2 diabetes" and see "Patient information: Fibroids").

RISK FACTORS — Several risk factors are associated with a higher rate of miscarriage. Age — Older women are more likely to have a miscarriage than younger women. Number of pregnancies — The risk of miscarriage increases in women who have had been pregnant previously. That is, women who have been pregnant two or more times have an increased risk of miscarriage. Previous miscarriage — Having a miscarriage in the past may increase the risk for a future miscarriage. As an example, the risk of miscarriage in future pregnancy is about 20 percent after one miscarriage, 28 percent after two, and 43 percent after three or more miscarriages. By comparison, only 5 percent of women whose previous pregnancy was successful miscarried in the next pregnancy. Smoking — There is evidence that smoking more than 10 cigarettes a day increases the risk of miscarriage. Alcohol — Drinking more than 30 ounces of alcohol per month doubled the risk of miscarriage in one study. In another, there was an increased risk of miscarriage in women who drank more than 3 drinks per week in the first 12 weeks of pregnancy. No amount of alcohol is known to be safe during pregnancy. Fever — Pregnant women who develop fevers of 100ºF (37.5ºC) or more appear to have an increased risk of miscarriage. Trauma — Trauma to the uterus can increase the risk of miscarriage. This includes some forms of prenatal testing, such as amniocentesis or chorionic villus sampling. (See "Patient information: Amniocentesis" and see "Patient information: Chorionic villus sampling"). Caffeine — In one study, some women who ingested 500 mg of caffeine per day had a significantly increased risk of miscarriage (8 ounces of coffee contains 100 to 135 mg of caffeine). Other causes — Women who are exposed to certain substances or conditions may have an increased risk of congenital abnormalities and miscarriage. This includes exposure to certain infections, medications, radiation, physical stresses, and environmental chemicals.

SIGNS AND SYMPTOMS — The most common signs of miscarriage are vaginal bleeding and abdominal pain early in pregnancy. These problems should always be evaluated by a clinician. However, bleeding and discomfort can occur in normal pregnancies. In many cases, bleeding resolves on its own and the pregnancy continues normally without further problems.

Based on particular signs and symptoms, a woman may be diagnosed as follows:

Threatened miscarriage — A woman who has vaginal bleeding early in pregnancy but no other signs of problems is said to have a threatened miscarriage. The cervix, or opening to the uterus, is closed, and the uterus is the right size for the woman's particular stage of pregnancy. If the pregnancy is far enough along, a fetal heart beat may be noted. In many women with threatened miscarriage, the bleeding subsides and the pregnancy continues to term. In others, the bleeding becomes heavier and miscarriage occurs.

Inevitable miscarriage — This means a miscarriage cannot be avoided. The cervix is open, bleeding is heavy or increasing, and abdominal cramping is present.

Incomplete miscarriage — An incomplete miscarriage means that the woman has passed much of the pregnancy tissue, but some remains in the uterus. Typically, the fetus has been passed, but bits of the placenta remain. The cervix remains open, and bleeding may be heavy.

Complete miscarriage — A woman who passes all of the pregnancy tissue is said to have had a complete miscarriage. This is common in miscarriages that occur before 12 weeks of pregnancy. After the miscarriage there is a period of bleeding and cramping, which resolves without medical intervention. On examination, the clinician typically finds that the cervix is closed, and there is no sign of a pregnancy sac in the uterus. Ultrasound examination confirms the diagnosis.

Septic miscarriage — Some women who have miscarriage develop an infection in the uterus. This is known as a septic miscarriage. Symptoms include fever, chills, malaise, abdominal pain, vaginal bleeding, and vaginal discharge, which may be thick and may have an unpleasant odor.

DIAGNOSIS — In some cases, miscarriage is evident based on the woman's symptoms and the physical exam. As an example, with inevitable miscarriage, the cervix is open and pregnancy tissue may be seen in the cervix.

However, in many cases of vaginal bleeding in early pregnancy, ultrasound is used to establish a diagnosis, and/or to help determine if the pregnancy is "viable", that is, whether it is capable of progressing to term. Ultrasound uses sound waves to visualize the structures inside the uterus. In early pregnancy, the exam is often done through the vagina.

Ultrasound — In a woman who has had a complete miscarriage, no pregnancy sac or embryo will be seen on ultrasound. In other women, a pregnancy sac will be seen but it will be abnormal or an embryo will not be present, indicating that the pregnancy is not viable.

If an embryo is present, its size is measured and compared to the size that is expected at the woman's stage of pregnancy. The sac and other materials surrounding the embryo are also examined to look for abnormalities in these structures.

Fetal heart beat — At about 6 weeks after the last menstrual period, the motion of the fetal heart should be visible on ultrasound. If the pregnancy has progressed to the stage where a heart beat should be present, the failure to detect a heart beat during an ultrasound exam indicates that the pregnancy has likely ended.

On the other hand, the presence of a fetal heart beat (in the absence of other abnormalities in the pregnancy) indicates the pregnancy may still be viable and that miscarriage may not occur.

Doctors will also evaluate the rate of the fetal heart. A fetal heart beat that is slower than normal (120 to 170 beats per minute) can indicate that a miscarriage is likely.

TREATMENT OPTIONS — Once it has been determined that a miscarriage is inevitable or is already occurring , several options are available depending on the stage of the miscarriage, the condition of the mother, and other factors. The three main options are: observation, medical treatment, or surgical treatment.

Observation — In some situations, women having a miscarriage require little treatment. Many women with complete miscarriage fall into this group. In addition, women who miscarry at less than 13 weeks of pregnancy and have stable vital signs and no signs of infection can often be managed without medical or surgical treatment. In time, the contents of the uterus will pass, usually within two weeks of diagnosis, but sometimes as long as 3 to 4 weeks later. Once the contents have been passed, an ultrasound is done to ensure that the miscarriage is complete.

Medical treatment — In some cases, medications can be given to stimulate the uterus to pass the pregnancy tissue. The medicine can be given by mouth or vaginally, and works over several days.

Surgical treatment — The conventional treatment for early miscarriage is a surgical procedure called dilation and curettage, or D and C. The cervix (the opening to the uterus) is dilated, and an instrument is inserted that uses suction and/or a gentle scraping motion to remove the contents of the uterus.

As with any surgical procedure, there are risks of complications. The risks associated with D and C are small, and include perforation of the uterus, formation of scar tissue in the uterus, trauma to the cervix, and infection, which could lead to future fertility problems. The procedure is done in women who do not want to wait for spontaneous passage of the pregnancy, and in women with heavy bleeding or infection.

AFTER MISCARRIAGE — Following miscarriage, a woman is advised to avoid having sex or putting anything into the vagina, such as a douche or tampon. Women have traditionally been told to wait two to three months before trying to become pregnant again, although several studies have shown no increased risks with a shorter interval. Any type of contraception, including an intrauterine device, may be started immediately.

Medications may be given to help decrease bleeding and reduce infection. In addition, women who have an Rh negative blood type (ie, A, B, AB, or O negative) need to receive a drug called Rh(D) immune globulin (RhoGam®). This medicine helps protect future fetuses against problems that can occur if an Rh negative mother is carrying a baby who is Rh positive.

Emotional health — Women experience a range of emotions following miscarriage; there is no right or wrong way to feel. The loss of a pregnancy can cause significant grief. Sometimes these reactions are strong and long-lasting. A woman should let her healthcare provider know if she is feeling profound sadness or depression following pregnancy loss, especially if it continues for greater than two weeks. Referral for grief counseling or other treatment may be beneficial. (See "Patient information: Depression in adults").

WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine

(www.nlm.nih.gov/medlineplus/healthtopics.html)
The March of Dimes

(www.marchofdimes.com)
Pregnancy & Infant Loss Support, Inc.

(www.nationalshareoffice.com)


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3. Ankum, WM, Wieringa-De Waard, M, Bindels, PJ. Management of spontaneous miscarriage in the first trimester: an example of putting informed shared decision making into practice. BMJ 2001; 322:1343.
4. Demetroulis, C, Saridogan, E, Kunde, D, Naftalin, AA. A prospective randomized control trial comparing medical and surgical treatment for early pregnancy failure. Hum Reprod 2001; 16:365.