WHOの勧告

【原文】
2.2.4 Surgical methods of abortion

2.2.4.1 Vacuum aspiration

The recommended surgical technique for abortion up to gestational age less than 15 weeks is vacuum aspiration (57). The high efficacy of vacuum aspiration has been well established in several randomized controlled trials. Complete abortion rates between 95% and 100% are reported (55, 56). Electric and manual vacuum technologies appear to be equally effective; however, the use of manual vacuum aspiration is associated with less pain in pregnancies under 9 weeks’ gestation and with more procedural difficulty over 9 weeks’ gestation (57). Vacuum aspiration under 14 weeks’ gestation is more effective and associated with fewer minor complications than medical abortion (56, 58).

Vacuum aspiration involves evacuation of the con- tents of the uterus through a plastic or metal cannula, attached to a vacuum source. Electric vacuum aspiration (EVA) employs an electric vacuum pump. With manual vacuum aspiration (MVA), the vacuum is created using a hand-held, hand-activated, plastic 60 ml aspirator (also called a syringe). Available aspirators accommodate different sizes of plastic cannula, ranging from 4 mm to 16 mm in diameter. For each procedure, the appropriately sized cannula should be chosen based on the gestational age and the amount of cervical dilatation present; generally, the diameter of the cannula corresponds to the gestational age in weeks. Some cannula and most aspirators are reusable after being cleaned and high-level disinfected or sterilized. Foot-operated mechanical pumps are also available.

Depending on the duration of pregnancy, abortion with vacuum aspiration takes from 3 to 10 minutes to complete and can be performed on an outpatient basis, using analgesics and/or local anesthesia. The completion of abortion is verified by examination of the aspirated tissue. In very early pregnancy, the cannula may be inserted without prior dilatation of the cervix. Usually, however, dilatation using mechanical or osmotic dilators, or pharmacological agents such as misoprostol or mifepristone, is required before insertion of the cannula (see Section 2.2.1). Generally, vacuum-aspiration procedures can be safely completed without intrauterine use of curettes or other instruments. No data suggest that use of curettage after vacuum aspiration decreases the risk of retained products (59).

Most women who have a first-trimester abortion with local anesthesia feel well enough to leave the health-care facility after observation for about 30 minutes in a recovery room. Longer recovery periods are generally needed for abortions performed later in pregnancy and when sedation or general anesthesia has been used.

Vacuum aspiration is a very safe procedure. A study of 170 000 first-trimester abortions conducted in New York City by vacuum aspiration reported that less than 0.1% of the women experienced serious complications requiring hospitalization (60). Though rare, complications with vacuum aspiration can include pelvic infection, excessive bleeding, cervical injury, incomplete evacuation, uterine perforation, anesthetic complications and ongoing pregnancy (1, 2). Abdominal cramping and menstrual-like bleeding occur with any abortion procedure.

2.2.4.2 Dilatation and curettage

D&C involves dilating the cervix with mechanical dilators or pharmacological agents and using sharp metal curettes to scrape the walls of the uterus.

D&C is less safe than vacuum aspiration (61) and considerably more painful for women (62). Therefore, vacuum aspiration should replace D&C. The rates
of major complications of D&C are two to three times higher than those of vacuum aspiration (3). Randomized controlled trials comparing D&C with vacuum aspiration found that, for up to 10 weeks since the LMP, vacuum aspiration is quicker and associated with less blood loss than D&C (63, 64).

Where it is still practiced, all possible efforts should be made to replace D&C with vacuum aspiration, to improve the safety and quality of care for women. Where no abortion services are currently offered, vacuum aspiration should be introduced rather than D&C. At sites where vacuum aspiration has yet to be introduced, managers must ensure that proper pain- management protocols are followed, and that D&C procedures are performed by well-trained staff under adequate supervision.