Induced abortion is the intentional ending of a pregnancy by surgery or drugs.

• A pregnancy may be ended by surgically removing the contents of the uterus or by taking certain drugs.
• Complications are uncommon when an abortion is done by a trained health care practitioner in a hospital or clinic.

Worldwide, the status of abortion varies from being legally banned to being available on request. About two thirds of the women in the world have access to legal abortion. In the United States, elective abortion (abortion initiated by personal choice) is legal during the 1st trimester (up to 12 weeks). After 12 weeks, whether elective abortion is legal varies from state to state. In the United States, about 25% of all pregnancies are ended by elective abortion, making it one of the most common surgical procedures done.

Did You Know... Abortion is one of the most common surgical procedures done in the United States.

Methods

Abortion methods include surgery (surgical evacuation) and drugs to stimulate contractions of the uterus. The method used depends in part on how long a woman has been pregnant. Ultrasonography is usually done to estimate the length of the pregnancy. Surgical evacuation can be used for most pregnancies. Drugs can be used for some pregnancies that are very early or late (more than 15 weeks). For abortions done early in the pregnancy, only a local anesthetic may be needed. For abortions done later, a general anesthetic may be needed.

Surgical Evacuation: The contents of the uterus are removed through the vagina. Surgical evacuation is used for more than 95% of abortions. Different techniques are used depending on the length of the pregnancy.

For pregnancies of less than 12 weeks, suction curettage is almost always used. Typically, doctors use a small, flexible tube attached to a vacuum source, usually a machine suction pump or hand pump but occasionally a vacuum syringe. The tube is inserted through the opening of the cervix into the interior of the uterus, which is then gently and thoroughly emptied. Sometimes this procedure does not terminate the pregnancy, especially when the procedure is done during the first week after a menstrual period is missed.

Sometimes doctors have to widen (dilate) the cervix to pass the suction tube through the cervix and into the uterus. For example, for pregnancies of 7 to 12 weeks, the cervix is usually dilated because a larger tube is used. For pregnancies of 4 to 6 weeks, a smaller tube is used, so little or no dilation is usually needed. To reduce the possibility of injuring the cervix during dilation, doctors may use natural substances that absorb fluids, such as dried seaweed stems (laminaria), rather than mechanical devices. Laminaria are inserted into the opening of the cervix and left in place for at least 4 to 5 hours, usually overnight. As the laminaria absorb large amounts of fluid from the body, they expand and stretch the opening of the cervix. Drugs such as prostaglandins can also be used to dilate the cervix.

For pregnancies of more than 12 weeks, dilation and evacuation is usually used. After the cervix is dilated, suction and forceps are used to remove the fetus and placenta. Then the uterus may be gently scraped to make sure everything has been removed. This technique results in fewer minor complications than do the drugs used to induce abortion. However, for pregnancies of more than 18 weeks, dilation and evacuation can cause serious complications, such as damage to the uterus or intestine.

Drugs: Drugs to induce abortions may be used for pregnancies of less than 9 weeks or more than 15 weeks. Drugs are typically used for very early abortions, before the sac containing the embryo and placenta is clearly visible on an ultrasound scan. Options include mifepristone (RU-486) and prostaglandins, such as misoprostol.

Mifepristone, given by mouth, blocks the action of the hormone progesterone, which prepares the lining of the uterus to support the fetus. Mifepristone is used only for pregnancies of less than 9 weeks.

Prostaglandins are hormonelike substances that stimulate the uterus to contract. They may be used with mifepristone for pregnancies of less than 9 weeks or used alone for pregnancies of more than 15 weeks. Prostaglandins may be swallowed, held in the mouth (next to the cheek or under the tongue) until they dissolve, injected, or placed in the vagina. A prostaglandin is given after mifepristone when both are used. The most common regimen involves taking 1 to 3 tablets of mifepristone and, 2 days later, taking a prostaglandin (misoprostol) by mouth or vaginally. This regimen causes abortion in about 95% of women. If abortion does not occur, surgical evacuation is done. For pregnancies of more than 15 weeks, two tablets placed in the vagina every 6 hours are almost 100% effective within 48 hours.

Complications

In general, abortion has a higher risk of complications than contraception or sterilization, especially for young women. However, complications from abortion are uncommon when it is done by a trained health care practitioner in a hospital or clinic. Serious complications occur in fewer than 1% of women.

The risk of complications is related to the length of the pregnancy: The longer a woman has been pregnant, the greater the risk. Risk is also related to the method used.

• Surgical evacuation: The uterus is perforated by a surgical instrument in 1 of 1,000 abortions. Less often, the intestine or another organ is injured. Severe bleeding occurs during or immediately after the procedure in 6 of 10,000 abortions. The instruments used can tear the cervix, especially in pregnancies of more than 12 weeks. Later, infections may develop. Very rarely, the procedure or a subsequent infection causes scar tissue to form in the lining of the uterus, resulting in sterility. This disorder is called Asherman's syndrome.
• Drugs: Mifepristone and the prostaglandin misoprostol have side effects. The most common are crampy pelvic pain, vaginal bleeding, and gastrointestinal problems such as nausea, vomiting, and diarrhea. Infection is less likely when drugs are used than when surgery is used.
• Either method: Bleeding and infection can occur if part of the placenta is left in the uterus. Later, particularly if the woman is inactive, blood clots may develop in the legs. If the fetus has Rh-positive blood, a woman who has Rh-negative blood may produce Rh antibodies—as in any pregnancy, miscarriage, or delivery. Such antibodies may endanger subsequent pregnancies. Giving the woman injections of Rh₀(D) immune globulin prevents antibodies from developing (see Allergic Reactions and Other Hypersensitivity Disorders: Autoimmune Disorders).

Elective abortion probably does not increase risks for the fetus or woman during subsequent pregnancies.

Most women do not have psychologic problems after an abortion. However, problems are more likely to occur in women who had psychologic symptoms before pregnancy, who ended a desired pregnancy for health reasons, who were very ambivalent about the abortion, who are adolescents, who had a late abortion, or who obtained an abortion illegally.

Last full review/revision August 2007 by Daniel R. Mishell, Jr., MD