Drug Name
Misoprostol (Cytotec)
Description
Synthetic prostaglandin E1 analog. Abortifacient effect results from increased frequency of uterine contractions. May be used alone or as part of regimen with mifepristone up to 49 d since LMP or with methotrexate up to 63 d since LMP.
Adult Dose
During second trimester (17-24 wk): 200-mcg tab placed in posterior vaginal fornix, repeat in 12 h; if fetus not delivered in 24 h, add 20-mg dinoprostone intravaginal supp q3h until delivery of fetusWith mifepristone: 400 mcg PO 48 h after mifepristoneWith methotrexate: 800 mcg PV 5-7 d after methotrexate, if no vaginal bleeding repeat in 24 h
Pediatric Dose
Not established
Contraindications
Documented hypersensitivity
Interactions
None reported
Pregnancy
X - Contraindicated in pregnancy
Precautions
Caution in patients with renal impairment and in elderly patients
Drug Name
Dinoprostone, PGE2 (Prostin E2 suppository)
Description
Induces uterine contractions by stimulating myometrium. Used during second-trimester medical abortions if fetus does not deliver in 24 h. Also used during instillation technique abortions to make cervix inducible.
Adult Dose
Medical abortion: 20 mg PV q3h until delivery of fetus occurs
Pediatric Dose
Not established
Contraindications
Documented hypersensitivity; acute pelvic inflammatory disease; uterine fibroids; cervical stenosis
Interactions
Increased effects of oxytocics
Pregnancy
C - Safety for use during pregnancy has not been established.
Precautions
Caution in patients with anemia, asthma, cervicitis, infected endocervical lesions, acute vaginitis, diabetes mellitus, epilepsy, compromised uteri (ie, fibroid tumors, surgery), cardiovascular disease, hypertension or hypotension, renal or hepatic impairment; associated with GI distress, headache, arrhythmias, angina, uterine rupture, dyspnea, wheezing
Surgical therapy: Surgical abortion techniques available for therapeutic termination of pregnancy include the following:
Manual vacuum aspiration (ie, menstrual extraction)
Suction curettage
Dilation and extraction
Hysterotomy
Hysterectomy
The choice of surgical abortion technique depends on the gestational age of the pregnancy; the expertise of the available medical staff; the clinical importance of obtaining an intact fetus; and the medical, surgical, psychiatric, and anesthetic contraindications to the various techniques. See Surgical Management of Abortion for a detailed discussion of surgical abortion techniques.
Preoperative details: For selective reduction procedures, evaluation of the fetuses using chorionic villus sampling or amniocentesis can assist in selection of the appropriate fetuses for reduction.
The use of ultrasound to assess fetal growth, fetal heart rate, and fetal nuchal thickening can also be helpful in the selection process. Criteria such as nuchal translucency of more than 3 mm, a lag in growth longer than 3 days, or a heart rate less than 80 beats per minute can be used to select the appropriate fetus for reduction.
COMPLICATIONS
As with all interventions, complications are associated with all methods used for termination of pregnancy. For complications associated with surgical abortion, see Surgical Management of Abortion. Medical abortions in the first trimester are safe and well-tolerated procedures. The major problems are decreased effectiveness of medical abortion with increasing gestational age and the long interval between administration of medication to completion of abortion for certain medications (eg, methotrexate, tamoxifen).
Complications and adverse effects associated with specific medications are as follows:
Methotrexate and misoprostol: Complications associated with the proper dose are rare, but the following can occur:
Stomatitis (0.66%)
GI morbidity
Nausea (10-37%)
Vomiting (7-25%)
Diarrhea (2-52%)
Thrombocytopenia
Chemical hepatitis
Failed abortion (4-12%)
Mifepristone and misoprostol
Transfusion (0.1%)
Pain requiring narcotic analgesia (4-15%)
Vomiting (12-44%)
Diarrhea (7-39%)
Failed abortion (2-6%)
Misoprostol and tamoxifen
Vomiting (28%)
Diarrhea (8%)
Failed abortion (8%)
Misoprostol alone
Nausea (24%)
Vomiting (25-26%)
Diarrhea (58%)
Headache (13-15%)
Fever (35%)
Chills (54-57%)
Failed abortion (6-8%)
Complications associated with instillation techniques are as follows:
Hemorrhage requiring transfusion (0.32-1.72%)
Infection
Incomplete abortion
Cervical laceration
Hypernatremia and sodium load (saline)
Muscle necrosis (myometrial injection of saline or urea)
Adverse GI effects
Unintended surgery (0.04-0.08 cases per 100 instillations)
Disseminated intravascular coagulopathy (saline, 658 cases per 100,000 instillations)
Urea instillation abortions are reported to be safer than saline abortions. Prostaglandin-induced second-trimester abortions are safer than saline abortions and have a lower induction-to-completion time.
Of all methods of second-trimester abortion, the safest procedure (using mortality surveillance data) is dilation and extraction. Intermediate risk of mortality occurs with instillation procedures. The highest mortality rates for second-trimester abortions are associated with major surgical procedures (ie, hysterotomy, hysterectomy).
Selective reduction procedures are not included in the statistics for second-trimester abortions. For the rare condition of monochorionic twins, selective reduction cord occlusion techniques are reported by Challis et al to have premature rupture of membranes in up to 30% of cases. The more common method of intracardiac injection techniques for selective reduction is associated with premature rupture of membranes in 13% of triplet pregnancies reduced to twins and in 19.3% of quadruplets reduced to twins. The risk of miscarriage in a pregnancy undergoing selective reduction is inversely proportional to the number of fetuses in the initial pregnancy (ie, quintuplet, 24.8%; triplet, 8.3%)
OUTCOME AND PROGNOSIS
Advantages of medical abortion are as follows:
Can be performed without delay
Avoids anesthesia and surgical risks
Psychological advantage - Patient control
Wider availability of abortion services
Increased patient choice
Advantages of surgical abortion are as follows:
More effective than medical abortion
Shorter completion time
Shorter bleeding duration
No exposure to potential teratogens
Can be performed later in gestational age
Fewer visits
Surgical abortion is 99% effective in terminating pregnancy. Medical abortion using mifepristone and misoprostol has a mean effectiveness of 94%. Medical abortion using methotrexate and misoprostol has effectiveness ranging from 88-96%. Medical abortion in the second trimester using misoprostol has effectiveness ranging from 40-89% within 24 hours. Instillation methods of abortion have effectiveness ranging from 81-86% at 48 hours to 97% at 72 hours.
As with all interventions, complications are associated with all the methods of termination of pregnancy. For complications associated with surgical abortion techniques, see Surgical Management of Abortion.
Medical abortions in the first trimester are very safe and well-tolerated procedures. The major problem is decreased efficacy with increasing gestational age. In the case of methotrexate, a long period of time between administration of medication to abortion is problematic.
First-trimester abortions performed by surgical or medical methods are well tolerated, have little effect on future fertility, and are not associated with long-term psychological consequences. Second-trimester abortions are well known to be associated with increased risk of morbidity and mortality with increasing gestational age. An association of increased risk for preterm delivery after dilation with metal dilators has been reported.
FUTURE AND CONTROVERSIES
Future research is expected to evaluate alternative protocols for medical abortion. Research is expected to continue evaluating other medications for medical abortion, including further research using the following:
Tamoxifen, an antiestrogen that interferes with decidual development in an animal model and is associated with incomplete and threatened abortion in humans
Epostane (3beta-hydroxysteroid dehydrogenase inhibitor), which works by blocking the synthesis of progesterone
The potential exists for wider use of medical management of incomplete and missed abortions as the techniques for medical abortion become commonplace.
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