Forms of abortion

Spontaneous abortion

Spontaneous abortions, generally referred to as miscarriages, occur when an embryo or fetus is lost due to natural causes. A miscarriage is spontaneous loss of the embryo or fetus before the 20th week of development. Spontaneous abortions after the 20th week are generally considered to be preterm deliveries. Most miscarriages occur very early in a pregnancy. Approximately 10-50% of pregnancies end in miscarriage, depending upon the age and health of the pregnant woman.

The risk for spontaneous abortion is greater in those with a history of more than three previous (known) spontaneous abortions, those who have had a previous induced abortion, those with systemic diseases, and in women over age 35.

Other causes can be infection (of either the woman or the fetus), immune responses, or serious systemic diseases of the woman.

A spontaneous abortion can also be caused by accidental trauma; intentional trauma to cause miscarriage is considered an induced abortion. Some governments have laws increasing the criminal liability of a person who causes a miscarriage during an assault or other violent crime.

Induced abortion

A pregnancy can be intentionally aborted in a number of ways. The manner selected depends chiefly upon the gestational age of the fetus, in addition to the legality, regional availability, and/or doctor-patient preference for specific procedures.

Surgical abortion

In the first fifteen weeks, suction-aspiration or vacuum abortion is the most common method. Manual vacuum aspiration, or MVA abortion, consists of removing the fetus or embryo by suction using a manual syringe, while the Electric vacuum aspiration or EVA abortion method uses an electric pump. These techniques are equivalent, differing only in the mechanism use to apply suction. From the fifteenth week up until around the twenty-sixth week, a surgical dilation and evacuation (D & E) is used. D & E consists of opening the cervix of the uterus and emptying it using surgical instruments and suction.

Dilation and curettage (D & C) is a standard gynaecological procedure performed for a variety of reasons, including examination of the uterine lining for possible malignancy, investigation of abnormal bleeding, and abortion. Curettage refers to the cleaning of the walls of the uterus with a curette. The World Health Organization recommends this sort of procedure, also called Sharp Curettage, only when MVA is unavailable.Sharp curettage only accounted for 2.4% of abortion procedures in the US in 2002. The term "D and C" can more generally be used to refer to the first trimester abortion procedure, irrespective of the method used to perform the procedure.

Other techniques must be used to induce abortion in the third trimester. Premature delivery can be induced with prostaglandin; this can be coupled with injecting the amniotic fluid with caustic solutions containing saline or urea. Very late abortions can be brought about by intact dilation and extraction (intact D & X), which requires the surgical decompression of the fetus's head before evacuation, and is sometimes termed "partial-birth abortion." A hysterotomy abortion, similar to a caesarian section but resulting in a terminated fetus, can also be used at late stages of pregnancy. It can be performed vaginally, with an incision just above the cervix, in the late mid-trimester.

Chemical abortion

Effective in the first trimester of pregnancy, chemical (also referred to as a medical abortion), or non-surgical abortions comprise 10% of all abortions in the United States and Europe. The process begins with the administration of either methotrexate or mifepristone, followed by misoprostol. When appropriately used, 98% of women undergoing medical termination of pregnancy will experience completed abortion without surgical intervention. The Food and Drug Administration currently approves the use of mifepristone up to 49 days gestation (7 weeks), though evidence based regimens exist for its use up to 61 days gestation with similar success rates. Misoprostol alone can also be used, though it is not FDA approved for this purpose. Misoprostol (Cytotec) alone has the advantage of costing less than one dollar for an effective dose, as opposed to several hundred dollars for an effective dose of mifepristone. In cases of failure of medical abortion, vacuum or manual aspiration is used to complete the abortion surgically.

Other means of abortion

Historically, a number of herbs reputed to possess abortifacient properties have been used in folk medicine: tansy, pennyroyal, black cohosh, and the now-extinct silphium (see history of abortion). The use of herbs in such a manner can cause serious — even lethal — side effects, such as multiple organ failure, and is not recommended by physicians.

Abortion is sometimes attempted through means of trauma to the abdomen. The degree of force applied, if severe, can cause serious internal injuries without necessarily succeeding in inducing miscarriage. Both accidental and deliberate abortions of this kind can be subject to criminal liability in many countries. In Burma, Indonesia, Malaysia, the Philippines, and Thailand, there is an ancient tradition of attempting abortion through forceful abdominal massage.

Reported methods of unsafe, self-induced abortion include the misuse of the ulcer drug Misoprostol and the insertion of non-surgical implements such as knitting needles and clothes hangers into the uterus.