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Abortion - threatened

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Contents of this page:

Illustrations

Miscarriage
Miscarriage
Early pregnancy
Early pregnancy

Alternative names    Return to top

Threatened miscarriage; Threatened spontaneous abortion

Definition    Return to top

A threatened abortion is a condition of pregnancy, occurring before the 20th week of gestation, that suggests potential miscarriage may take place.

Causes, incidence, and risk factors    Return to top

Approximately 20% of pregnant women experience some vaginal bleeding, with or without abdominal cramping, during the first trimester. This is known as a threatened abortion. However, most of these pregnancies go on to term with or without treatment. Spontaneous abortion occurs in less than 30% of the women who experience vaginal bleeding during pregnancy.

In the cases that result in spontaneous abortion, the usual cause is fetal death. Such death is typically the result of a chromosomal or developmental abnormality. Other potential causes include infection, maternal anatomic defects, endocrine factors, immunologic factors, and maternal systemic disease.

Estimates report that up to 50% of all fertilized eggs abort spontaneously, usually before the woman knows she is pregnant. Among known pregnancies, the rate is approximately 10%. These usually occur between 7 and 12 weeks of gestation. Increased risk is associated with women over age 35, women with systemic disease (such as diabetes or thyroid dysfunction), and those with a history of 3 or more prior spontaneous abortions.

Symptoms    Return to top

Note: With true miscarriage, low back pain or abdominal pain (dull to sharp, constant to intermittent) typically occurs and tissue or clot-like material may pass from the vagina.

Signs and tests    Return to top

Pelvic examination reveals a cervix that is neither thinned (effaced) nor open (dilated). The presence of effacement or dilation is consistent with impending miscarriage.

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

Treatment    Return to top

Activity restrictions vary, from avoiding some forms of exercise to complete bed rest. Restricting activity will not guarantee that a miscarriage will not occur. Health care providers typically recommend pelvic rest (abstaining from intercourse, douching, tampon use) until symptoms resolve. The woman's condition should be monitored carefully.

The use of progesterone is controversial. The potential benefit is the relaxation of smooth muscle, including the muscles of the uterus. However, this may increase the potential risk of an incomplete abortion or an abnormal pregnancy. In the absence of a luteal phase defect, progesterone supplementation should not be used.

Expectations (prognosis)    Return to top

The probable outcome is good when the pregnancy continues to progress and all the symptoms disappear.

Complications    Return to top

Calling your health care provider    Return to top

It is imperative for a woman who knows she is (or is likely to be) pregnant and who has any signs or symptoms of threatened abortion to contact her prenatal health care provider immediately.

Prevention    Return to top

Early and comprehensive prenatal care decreases risk of miscarriage. It is preferable to detect and treat known maternal disorders before conception occurs. Avoiding environmental hazards such as x-rays and infectious diseases also decreases the risk of miscarriage in early pregnancy.

Spontaneous abortion is not preventable if there is fetal death. In fact, it is important for the uterus to expel all products of conception in such cases. A missed abortion occurs when a dead fetus is not expelled from the uterus. When only part of the dead fetus is expelled, it is an incomplete abortion.

Update Date: 10/18/2003

Updated by: Francisco L. Gaudier, M. D., Maternal Fetal Medicine, Jacksonville, FL. Review provided by VeriMed Healthcare Network.

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