Abortion, spontaneous

Causes and Risks:
The cause of most spontaneous abortions is fetal death due to fetal growth abnormalities, not caused by the mother. Other possible causes for spontaneous abortion include: infection, physical defects of the mother, hormone ( endocrine ) factors, immune responses, and serious systemic diseases of the mother (such as diabetes or thyroid problems).

It is estimated that up to 50% of all fertilized eggs die and are lost (aborted) spontaneously, usually before the woman knows she is pregnant . Among known pregnancies, the rate of spontaneous abortion is approximately 10% and usually occurs between the 7th and 12th weeks of pregnancy (gestation).

The risk for spontaneous abortion is increased in women over 35 years of age, women with systemic disease (such as diabetes or thyroid dysfunction) and those with a history of 3 or more prior spontaneous abortions.

Prevention:
Many of the spontaneous abortions that are caused by maternal diseases could be prevented through early (prior to conception) detection and treatment of the disease.

Reduced risks of spontaneous abortions have been attributed to early, comprehensive prenatal care and avoidance of environmental hazards (such as X-rays and infectious diseases).

Spontaneous abortion naturally occurs after fetal death. The dead tissue is discarded from the uterus and the woman resumes her normal menstrual cycle within a few weeks (usually). Note: it is frequently possible to become pregnant immediately after a spontaneous abortion, however it is recommended that you wait for one or two normal menstrual cycles before attempting another pregnancy .

On occasion, the uterus does not expel all of the fetal tissue, in which case it is considered incomplete. Incomplete spontaneous abortions may require surgical removal of the retained tissue.

If there is fetal death that is not accompanied by uterine expulsion of the dead tissue, it is considered a missed abortion. Signs of pregnancy decrease, the uterus begins shrinking to its original size, and a brownish or reddish vaginal discharge is often experienced. If spontaneous abortion does not occur in a reasonable amount of time (about 4 weeks), a D & C or D & E will have to be performed, or labor induced to remove the dead fetus.

When a mother's body is having difficulty sustaining a pregnancy, signs such as slight vaginal bleeding may occur. This is a threatened abortion , which means there is a possibility of abortion, but it is not inevitable. A pregnant woman who develops any signs or symptoms of threatened miscarriage should contact her prenatal provider immediately.

Symptoms:

Note: Approximately 20% of pregnant women experience some vaginal bleeding during the first trimester. Less than half of these women experience a spontaneous abortion .

Signs and Tests:
Pelvic examination may reveal moderate thinning of the cervix (effacement), increased cervical dilation, and evidence of ruptured membranes.

This disease may also alter the results of the following tests:



Treatment:
Treatment for threatened abortion varies from restrictions on some forms of exercise to complete bedrest. Abstaining from intercourse is usually recommended until signs have disappeared.

In the event of spontaneous abortion , the tissue passed from the vagina should be examined to determine the source of the tissue (fetal vs. hydatidiform mole ) and if any fetal tissue remains in the uterus ( incomplete abortion ). Missed abortions that do not abort naturally and incomplete spontaneous abortions may require surgical removal of retained tissue ( D & C procedure). Any further vaginal bleeding should be carefully monitored.

Prognosis:
Maternal outcome is good and complications are rare. Waiting a few months before trying to become pregnant again is usually recommended.

Complications:

  • Retained dead fetal tissue in the uterus is referred to as an incomplete abortion . This may cause infection and the retained uterine tissue must be removed surgically ( D & C (dilation and curettage)).
  • An infection may occur after either a complete or incomplete abortion.
  • In a missed abortion the pregnancy has continued for 4 weeks or longer following the death of the fetus. This usually occurs during the second trimester. Sometimes (if early enough in the pregnancy) a D & C or D & E can be performed to remove all of the dead tissue. Frequently labor must be induced to expel the dead fetus and other uterine tissue.
  • Dead fetus syndrome is the term used to describe a condition which affects the mother. If the fetus has died but the dead tissue has not been discarded by the uterus, an abnormal activation of blood clotting systems (coagulation and fibrinolytic systems) can develop in response to the release of anti-clotting chemicals from the retained dead fetus (missed abortion).



Call Your Healthcare Provider:
Call your health care provider if vaginal bleeding with or without cramping occurs during pregnancy .

Call your health care provider if you are pregnant and notice tissue or clot-like material passed vaginally (any such material should be collected and brought in for examination).