Abortion methods

First-trimester termination (at or below 12 weeks of gestation)

Both surgical and medical methods are available for termination of first-trimester pregnancies.

Surgical abortion

For surgical abortion, suction evacuation (vacuum aspiration) is performed for gestation under 12 weeks.

Cervical priming with misoprostol 400 mcg vaginally given 3 hours before operation is recommended to reduce cervical trauma during mechanical dilatation. Such a regimen has been proven ef­fective, although misoprostol is not licensed for such a purpose, and it can result in uterine cramps, bleeding, and unexpected expul­sion of the gestational products. A recent study showed that when misoprostol 400 mcg was given sublingually 1 hour before vacuum aspiration, it is still effective in dilating the cervix. The shortened interval will make it easier to organize a day-care abortion service (9). Non-steroidal anti-inflammatory drugs (NSAIDs) can be used for relief of pain encountered during misoprostol cervical priming without reducing its efficacy (10).

Pain control can be achieved by either general anaesthesia or local anaesthesia. Local anaesthesia has the advantage of being less costly, independent of theatre personnel and anaesthetists, and being asso­ciated with less anaesthesia- related complications. It can be achieved by paracervical block or topical anaesthetic jelly, and can be coupled with intravenous conscious sedation or Entonox inhalation as an ad­junct (8, 11, 12).

Intraoperatively, an aseptic technique should be observed and the cervix should be cleansed with antiseptic before uterine instrumen­tation (8). A bimanual examination should be performed to assess the size and direction of the uterus. The cervix is dilated gradually to a size, which can allow a suction catheter of a size in millimetres corresponding to the gestational age in weeks. The suction cannula is inserted gently until the fundus of the uterus is reached. Negative pressure is applied and the suction cannula is rotated to evacuate the uterine contents, until a ‘gritty’ sensation resulting from the clamping down of the emptied uterus around the cannula is felt. Uterotonic medications such as oxytocin should not be routinely used during vacuum aspiration as significant reduction of blood loss was not demonstrated in randomized trials, but may be con­sidered in cases where bleeding is heavy. The procedure should not be completed by sharp curettage. The aspirated tissue should be in­spected for the presence of gestational products. When gestational tissue can be visualized, routine histopathological examination of the tissue obtained at abortion is not recommended as it has limited clinical value (13). In case of uncertainty, however, particularly for early abortions before 7 weeks, histopathological examination may be indicated.

Acute complications of surgical abortion include anaesthetic- related complications, vasovagal reaction, cervical and lower genital tract injury, excessive haemorrhage, as well as uterine perforation which can be associated with visceral damage. Delayed surgical complications may include endometritis and pelvic infection, sec­ondary bleeding, retained products of conception, cervical stenosis or incompetence, and Asherman syndrome.

Medical abortion

For medical abortion, the use ofmifepristone followed by misoprostol 24-48 hours later is the recommended regimen. Mifepristone is a synthetic compound which blocks the progesterone receptor.

The regimens recommended by WHO are as follows (8):

• For pregnancies at or below 7 weeks: mifepristone 200 mg, given as a single oral dose, followed 24-48 hours later by a single oral dose of misoprostol 400 mcg.

• For pregnancies between 7 and 9 weeks: mifepristone 200 mg, given as a single oral dose, followed 24-48 hours later by misoprostol 800 mcg as a single vaginal, buccal, or sublingual dose.

• For pregnancies between 9 and 12 weeks: mifepristone 200 mg, given as a single oral dose, followed 36-48 hours later by misoprostol 800 mcg given vaginally, and then up to a maximum of four further doses of misoprostol 400 mcg every 3 hours given through either the vaginal or sublingual (if there is significant va­ginal bleeding) route.

It has been shown that vaginal misoprostol is more effective and has a lower incidence of side effects than oral misoprostol when combined with mifepristone in medical abortion, achieving a high complete abortion rate of over 95% (15). Both sublingual and va­ginal administration result in similar abortion rates without vaginal bleeding, although the sublingual route produces higher inci­dence of side effects (16).

Since mifepristone is not available in many countries, the use of prostaglandin alone has been studied for medical abortion. When used alone, vaginal misoprostol is more effective than oral misoprostol; it can be administered at 800 mcg up to three doses at 6-, 12-, or 24-hour intervals, and the complete abortion rate varied between 60% and 90% (19). In situations where the va­ginal route is not preferred, sublingual misoprostol at 3-hourly frequency is a reasonable alternative, although there can be more side effects (19). Abortion rates are reported at around 80% and 95% by 24 and 48 hours after administration of misoprostol, and failed abortion occurs in about 4-8% of cases for gestations up to 9 weeks.

Depending on the local laws, misoprostol can be administered either as in-patient or out-patient. In the latter case, the patient should be taught to monitor for and report complications, and follow-up care should be arranged to ascertain completeness of abortion.

Women with incomplete abortion can be offered the options of surgical evacuation or a repeat course of misoprostol. Side effects of mifepristone such as heavy bleeding, allergic reaction, and gastro­intestinal upset may uncommonly occur. Misoprostol is generally safe and well tolerated, although uterine cramps and bleeding are inevitably encountered, and other common minor side effects may

Table 54.1 Comparison between medical and surgical abortion methods in the first trimester

include fever, chills, gastrointestinal upset, and diarrhoea, which are transient and self-limiting. NSAIDs can be used for controlling these side effects without affecting the efficacy (20). Paracetamol is not an effective pain relief for abortion. Serious complications such as excessive haemorrhage, anaphylaxis, and septicaemia rarely occur. Once started, termination of pregnancy has to pro­ceed since multiple congenital defects have been reported with misoprostol exposure in early pregnancy (Table 54.1), notably the Mobius syndrome, although the absolute risk is only around the order of 1% (21).

Second-trimester termination (beyond 12 weeks of gestation)

Older methods such as intra- amniotic injection of hypertonic saline, urea, or ethacridine lactate is no longer recommended nowadays as these methods are more invasive, less effective than prostaglandins, and associated with a higher incidence of serious complications such as disseminated intravascular coagulopathy. Dilatation and evacu­ation in the second trimester can be a safe and effective procedure if performed by experienced personnel. The medical method, how­ever, is more commonly adopted for second-trimester abortions. Hysterotomy or hysterectomy are reserved as a surgical abortion method for special circumstances only.

Surgical method (dilatation and evacuation)

It is recommended that dilatation and evacuation (D&E) can be a safe method for second-trimester abortion if it is performed by per­sonnel with appropriate training and experience (3, 8). Preoperative cervical priming is essential. Osmotic dilators such as Lamicel or Dilapan are recommended for the purpose, although misoprostol is an acceptable alternative up to 18 weeks of gestation.

Anaesthesia, aseptic technique, and cervical cleansing with anti­septic are carried out similarly to first-trimester surgical abor­tions. Careful cervical dilatation up to 12-16 mm is required. Amniotic fluid aspiration followed by evacuation of fetal parts is carried out with a large suction cannula (14-16 mm) aided by forceps. The evacuated products should be inspected to confirm completeness. Haemorrhage is the most common complication of D&E; uterotonics can be used to control intraoperative bleeding. Other complications may include cervical tear, uterine perforation, incomplete evacuation, and postoperative infection. Continuous ultrasound guidance during the D&E procedure is recommended to reduce the risk of surgical complications such as uterine perfor­ation (3, 8, 22).

Medical method

The medical method using misoprostol with or without mifepristone priming is a widely recommended and adopted means for second- trimester induced abortions. Misoprostol stimulates the uterus to contract, leading eventually to the expulsion of the conceptus, like a ‘mini-labour’ with durations varying among individuals. Where available, pretreatment with mifepristone can sensitize the uterus to the effect of prostaglandins.

The recommended regimen is oral mifepristone 200 mg followed by vaginal misoprostol 800 mcg (or oral misoprostol 400 mcg) 36­48 hours later, and subsequently vaginal or sublingual misoprostol 400 mcg every 3 hours up to a maximum of four more doses (8). It has been shown that shortening the mifepristone-misoprostol interval to 12-24 hours instead of 36-48 hours resulted in only a slightly longer induction time (misoprostol-abortion interval) by 1-2 hour, but the overall abortion time (mifepristone-abortion interval) would be shorter (23); this is an acceptable alternative to accommodate individual patient or healthcare provider’s preference. The effectiveness is significantly lower if mifepristone is given at the same time as misoprostol (24). The average induction-abortion interval with this regimen is around 6 hours, with an abortion rate of 97% within 24 hours.

When mifepristone is not available, vaginal or sublingual misoprostol 400 mcg can be used alone every 3 hours for a maximum of five doses. Compared to when there is mifepristone priming, this has a longer induction-abortion interval (10-15 hours) and lower abortion rate (80-90%) within 24 hours, but is still considered an effective method. In case of significant vaginal bleeding, the vaginal route can be replaced by sublingual or oral routes. Women who fail to abort after 24 hours can be given a second course of misoprostol 12 hours after the last dose, and if it still fails, other prostaglandins or oxytocin can be used. For gestations beyond 20 weeks, the dose or frequency of prostaglandins should be reduced since the uterine sensitivity to prostaglandins increases with advancing gestation (al­though there is little evidence for the best regimen), and intracardiac injection of potassium chloride to the fetus to achieve fetal demise is also recommended before prostaglandin induction.

The most common side effects related to prostaglandin use in­clude nausea, vomiting, fever, chills, diarrhoea, and occasionally heavy haemorrhage. Infection and allergic reaction are uncommon complications after medical abortion. Uterine rupture is a rare but potentially fatal complication, with an incidence of 0.28% in women with previous caesarean delivery who undergo second-trimester abortion using misoprostol. Analgesia can be provided by NSAIDs without compromising the efficacy of prostaglandins; narcotics can be used if necessary. Oxytocin infusion can be given to aid pla­cental expulsion if not occurring 2 hours after expulsion of the fetus. Surgical evacuation is necessary only if bleeding is severe or placenta is retained.