Either medical or surgical methods can be used.
Early medical abortion can be performed up until the 9th week of pregnancy. It involves the use of two drugs. The first is mifepristone (also known as RU 486) which is taken orally. This is a progesterone antagonist. Progesterone is produced by the corpus luteum in early pregnancy and is responsible for maintaining the supporting uterine lining.
Between 36-46 hours after ingestion of mifepristone, prostaglandin vaginal pessaries are given which cause dilation of the neck of the womb. The lining of the womb, along with the pregnancy, are lost through the cervix.
Some medical procedures involve the use of methotrexate, a folate anatagonist.
Later medical abortions, performed after the 9th week, take longer and require more doses of prostaglandin. Very late medical abortions, performed with fetacidal procedures as described below, involve the use of prostaglandins injected directly into the womb to initiate premature labour.
The type of surgical procedure varies with the gestation of the pregnancy.
Suction aspiration is a surgical procedure which can be performed under local or general anaesthetic. It most often used in the first trimester of pregnancy (the first three months). Suction aspiration involves dilating the cervix and passing a suction curette (similar to a vacuum hose with an extremely sharp end) into the womb. In order to dilate the cervix, prostaglandin may be used as in early medical abortion described above. The suction curette is used to remove the pregnancy. The suction and cutting edge dismembers the fetus and the products are extracted by suction.
After the 15th week of pregnancy, dilatation, curettage and evacuation are performed in addition to suction. This procedure is carried out under a general anaesthetic. A wire loop is used to break the fetus apart and parts which cannot be removed by suction are removed piecemeal by forceps.
Partial Birth Abortion
This method is also known as intrauterine cranial decompression or intact dilation and extraction. It requires decompression of the fetal head before evacuation is performed. It is used for very late, third trimester abortions.
This involves the dilation of the cervix to allow the passage of forceps. Under ultrasound guidance, the fetus is turned to a breech position. The fetus is then partially extracted, with the head remaining in the uterus. The fetal skull is then punctured and the brain removed by suction. This allows the head to pass through the cervix.
This technique is used in the second and third trimester. Under ultrasound guidance, saline is instilled into the amnion in order to induce premature labour, which occurs 24-28 hours later. Fetacide occurs because the fetus swallows the instilled saline and dies of salt poisoning. The saline solution is also caustic and burns the fetal skin during the process.
Fetacidal procedures are required in late abortions, when there is a risk that a live fetus which could survive outside the uterus may be born. Fetacide involves stopping the fetal heart with an ultrasound guided injection of potassium chloride directly into the fetal heart.
Risks of Abortion Procedures
The risks of an abortion procedure include procedure failure, hemorrhage, perforation, damage to the cervix, infections and psychiatric morbidity.