Three types of abortion are available today in the United States, but by far the most common is a procedure called suction and curettage. About 90 percent of the nearly 1.6 million abortions performed each year in the United States are of this variety.

Used until about the 12th week of pregnancy, suction curettage involves widening the cervix and then removing the embryo and chorionic villus, or in later stages the placenta, with a suction tube. Doctors sometimes begin dilating the cervix the day before the abortion procedure, using laminaria (small slender rods made from a marine plant) or a synthetic sponge that swells as it absorbs moisture. In other cases, the cervix is dilated the day of the procedure by inserting and removing small metal rods of larger and larger width.

Suction curettage is usually performed under local anesthesia in either a doctor's office, a clinic or on an outpatient basis at a hospital. The procedure takes about 10 minutes. The woman is usually kept under observation for several hours afterward. The risk is low: Major complications, such as perforation of the uterus and hemorrhage, occur in fewer than one in 100 cases. Death occurs in fewer than one in 100,000 cases.

Between 13 and 15 weeks' gestation, doctors generally use a technique called dilation and evacuation (or D & E) to end a pregnancy. D & E procedures account for about 6 percent of the abortions performed in the United States. Like suction curettage, D & E requires that the cervix be dilated. But instead of using suction, doctors must use medical instruments to remove the fetus. Like suction and curettage, D & E abortions are also generally performed on an outpatient basis under local anesthesia, although sometimes general anesthesia is used.

Once a pregnancy reaches 16 weeks but before approximately 20 weeks, termination requires a more complicated procedure -- one that entails an overnight stay in the hospital. During this procedure, medication -- such as saline or prostaglandin -- is injected through the abdomen into the amniotic fluid in the uterus. The medication will cause the uterus to contract and expel the fetus eight to 24 hours later.

Sometimes vaginal suppositories are also used to promote the contractions, and in a small percentage of cases, doctors use intravenous oxytocin, a drug that helps the uterus contract. Some women who undergo a medication-induced abortion require curettage to remove remnants of the placenta.

Both D & E abortions and medication-induced procedures are riskier than suction and curettage. Serious complications occur in about two of every 100 women.

In less than 0.5 percent of women undergoing abortions, doctors must perform a either a hysterotomy (in which the fetus is removed through an abdominal incision, as in a cesarean section) or a hysterectomy (in which the uterus itself is removed surgically). These procedures are a last resort and are used only when the woman faces major complications -- such as a severe perforation of the uterus.