When And How Abortions Are Performed
In the United States and in European countries such as the Netherlands, more than 90 percent of all abortions are performed in the first trimester of pregnancy (up to twelve weeks from the last normal menstrual period). Most take place in outpatient clinics specially designed and equipped for this purpose. Nearly all abortions in the United States are performed by physicians, although two states (Montana and Vermont) permit physicians' assistants to do the procedure. A limited number of physicians in specialized clinics perform abortions during the second trimester of pregnancy, but only a few perform abortions after pregnancy has advanced to more than twenty-five weeks. Although hospitals permit abortions to be performed, the number is limited because the costs to perform an abortion in the hospital are greater and hospital operating room schedules do not allow for a large number of patients. In addition, staff members at hospitals are not chosen on the basis of their willingness to help perform abortions, while clinic staff members are hired for that purpose.
Most early abortions (up to twelve to fourteen weeks of pregnancy) are performed with some use of vacuum aspiration equipment. A machine or specially designed syringe is used to create a vacuum, and the suction draws the contents of the uterus into an outside container. The physician then checks the inside of the uterus with a curette, a spoon-shaped device with a loop at the end and sharp edges to scrape the wall of the uterus (Hern 1990).
Before the uterus can be emptied, however, the cervix (opening of the uterus) must be dilated, or stretched, in order to introduce the instruments. There are two principal ways this can be done. Specially designed metal dilators, steel rods with tapered ends that allow the surgeon to force the cervix open a little at a time, are used for most abortions. This process is usually done under local anesthesia, but sometimes general anesthesia is used. The cervix can also be dilated by placing pieces of medically prepared seaweed stalk called Laminaria in the cervix and leaving it for a few hours or overnight (Hern 1975, 1990). The Laminaria draws water from the woman's tissues and swells up, gently expanding as the woman's cervix softens and opens from the loss of moisture. The Laminaria is then removed, and a vacuum cannula or tube is placed into the uterus to remove the pregnancy by suction (Figure 1). Following this, the walls of the uterus are gently scraped with the curette.
After twelve weeks of pregnancy, performing an abortion becomes much more complicated and dangerous. The uterus, the embryo or fetus, and the blood vessels within the uterus are all much larger. The volume of amniotic fluid around the fetus has increased substantially, creating a potential hazard. If the amniotic fluid enters the woman's circulatory system, she could die instantly or bleed to death from a disruption of the blood-clotting system. This hazard is an important consideration in performing late abortions.
Ultrasound equipment, which uses sound waves to show a picture of the fetus, is used to examine the woman before a late abortion is performed. Parts of the fetus such as the head and long bones are measured to determine the length of pregnancy. The ultrasound image also permits determination of fetal position, location of the placenta, and the presence of any abnormalities that could cause a complication.
Between fourteen and twenty weeks of pregnancy, Laminaria is placed in the cervix over a period of a day or two, sometimes changing the Laminaria and replacing the first batch with a larger amount in order to increase cervical dilation (Hern 1990). At the time of the abortion, the Laminaria is removed, the amniotic sac (bag of waters) is ruptured with an instrument, and the amniotic fluid is allowed to drain out. This procedure reduces the risk of an amniotic fluid embolism, escape of the amniotic fluid into the bloodstream, and allows the uterus to contract to make the abortion safer. Using an ultrasound real-time image, the surgeon then places special instruments such as grasping forceps into the uterus and removes the fetus and placenta (Hern 1990). This has proven to be the safest way to perform late abortions, but it requires great care and skill.
Other methods of late abortion include the use of prostaglandin (a naturally occurring hormone), either by suppository or by injection (Hern 1988). Other materials injected into the pregnant uterus to effect late abortion include hypertonic (concentrated) saline (salt) solution, hypertonic urea, and hyperosmolar (concentrated) glucose solution.
Injections are also used with late abortions, especially those performed at twenty-five weeks or more for reasons of fetal disorder. The lethal injection into the fetus is performed several days prior to the abortion, along with other treatments that permit a safe abortion (Hern et al. 1993; Hern 2001).
Although surgical abortion is still performed outside the United States, medical abortion is growing in use in Europe and in the United States following the introduction in France in 1988 of mifepristone (also known as RU-486) and misoprostol, a synthetic prostaglandin. Mifepristone works by blocking the hormonal receptors in the placenta from receiving progesterone, which is necessary for continuation of the pregnancy. Along with misoprostol, mifepristone may cause a complete abortion in 95 percent of early pregnancies within a few days. Most patients do not require a surgical treatment for completion of the abortion.