In the United States, about half of pregnancies are unintended. About 40% of unintended pregnancies end in induced abortion; 90% of procedures are done during the 1st trimester.
In the United States, abortion of a previable fetus is regulated by state-specific restrictions (eg, mandatory waiting periods, gestational age restrictions). In countries where abortion is legal, abortion is usually safe and complications are rare. Worldwide, 13% of maternal deaths are secondary to unsafe induced abortion (1), and the overwhelming majority of these deaths occur in countries where abortion is illegal.
Pregnancy should be confirmed before abortion is induced. Often, gestational age is established by ultrasonography, but sometimes history and physical examination are used to estimate gestational age during the 1st trimester. Further evaluation should be considered if a woman is in the 2nd trimester and has risk factors for complications, eg, low-lying placenta or an anterior placenta plus a history of a uterine scar.
Antibiotics effective against reproductive tract infections (including chlamydia
First-trimester abortions often require only local anesthesia, but clinicians trained in using anesthesia may offer sedation in addition. For later abortions, deeper sedation is usually required.
Contraception (all forms) can be started immediately after an induced abortion at < 28 weeks gestation.
Reference
1. Ahman E, Shah IH: New estimates and trends regarding unsafe abortion mortality. Int J Gynaecol Obstet 115(2):121-126, 2011. doi:10.1016/j.ijgo.2011.05.027
Methods of Induced Abortion
Common methods of inducing abortion are
Instrumental evacuation of the uterus after cervical dilation
Medication induction (drugs to stimulate uterine contractions)
The method used depends in part on the gestational age. Instrumental evacuation can be used for most pregnancies. Drugs can be used for some pregnancies that are < 11 weeks or > 15 weeks. Medical abortion done before 11 weeks may be done on an outpatient basis. Patients who undergo medical abortion after 11 weeks should be observed because heavy bleeding is possible.
Uterine surgery (hysterotomy or hysterectomy) is a last resort, which is usually avoided and is associated with higher mortality rates. Hysterotomy also results in a uterine scar, which may rupture in subsequent pregnancies.
Instrumental evacuation
Typically at < 14 weeks, dilation and suction curettage (D & C) is used, usually with a large-diameter suction cannula inserted into the uterus.
At < 9 weeks, manual vacuum aspiration (MVA) can be used. MVA devices are portable, do not require an electrical source, and are quieter than electrical vacuum aspiration (EVA) devices. MVA may also be used to manage spontaneous abortion during early pregnancy. After 9 weeks, EVA is used; it involves attaching a cannula to an electrical vacuum source.
At 14 to 24 weeks, dilation and evacuation (D & E) is usually used. Forceps are used to dismember and remove the fetus, and a suction cannula is used to aspirate the amniotic fluid, placenta, and fetal debris. D & E requires more skill and requires more training than do other methods of instrumental evacuation.
Often, progressively increasing sizes of tapered dilators are used to dilate the cervix before the procedure. However, depending on gestational age and parity, clinicians may need to use another type of dilator instead of or in addition to tapered dilators to minimize the cervical damage that tapered dilators can cause. Choices include
Osmotic dilators such as laminaria (dried seaweed stems)
Osmotic dilators can be inserted into the cervix and left for ≥ 4 hours (often overnight if the pregnancy is >18 weeks). Osmotic dilators are usually used at > 16 to 18 weeks.
Medication abortion
Medication abortion can be used for pregnancies of < 11 weeks or > 15 weeks. If patients have severe anemia, medical induction at> 15 weeks should be done only in a hospital so that blood transfusion is readily available.
In the United States from 2014 to 2017, medication abortion accounted for 53% of abortions done at < 11 weeks 1.
Resolution of the pregnancy can be confirmed by one of the following:
Ultrasound follow-up
Measurement of beta-hCG on the day of administration and 1 week later
A urine pregnancy test 5 weeks after administration
Adverse effects of prostaglandins include nausea, vomiting, diarrhea, hyperthermia, facial flushing, vasovagal symptoms, bronchospasm, and decreased seizure threshold.
Methods references
1. Kapp N, Eckersberger E, Lavelanet A, Rodriguez MI: Medical abortion in the late first trimester: A systematic review. MMWR Recomm Rep 65 (4):1–66, 2016. doi: 10.15585/mmwr.rr6504a1
2. Jones RK, Jerman J: Abortion Incidence and Service Availability In the United States, 2014. Perspect Sex Reprod Health 49(1):17-27, 2017. doi:10.1363/psrh.12015
Complications of Induced Abortion
Complication are rare with legal abortion (serious complications in < 1%; mortality in < 1 in 100,000). Complication rates increase as gestational age increases. Overall complications are higher than those with contraception; however, rates are 14 times lower than those after delivery of a full-term infant, and rates have decreased in the last few decades.
Serious early complications include
Perforation of the uterus (0.1%) or, less often, of the intestine or another organ by an instrument
Major hemorrhage (0.06%), which may result from trauma or an atonic uterus
Laceration of the cervix (0.1 to 1%), which are typically superficial tenaculum tears but can be more serious and require repair
General or local anesthesia rarely causes serious complications.
The most common delayed complications include
Bleeding and significant infection (0.1 to 2%)
Delayed complications usually occur because placental fragments are retained. If bleeding occurs or infection is suspected, pelvic ultrasonography is done; retained placental fragments may be visible on an ultrasound scan. Mild inflammation is expected, but if infection is moderate or severe, peritonitis or sepsis may occur. Sterility may result from synechiae in the endometrial cavity (Asherman syndrome) or tubal fibrosis due to infection. Forceful dilation of the cervix in more advanced pregnancies may contribute to incompetent cervix. However, with evidence-based techniques including gentle suction and adequate cervical preparation, induced abortion is not expected to increase risks during subsequent pregnancies.
Psychologic complications do not typically occur but may occur in women who
Had psychologic symptoms before pregnancy
Had significant emotional attachment to the pregnancy
Have limited social support or feel stigmatized by their support system
Key Points
About 40% of unintended pregnancies end in induced abortion.
Common methods for abortion are instrumental evacuation of the uterus after cervical dilation or medication abortion (to induce uterine contractions).
Before doing an abortion, confirm that the woman is pregnant, and if so, determine gestational age based on history and physical examination and/or ultrasonography.
Serious complications (eg, uterine perforation, major bleeding, serious infection) occur in < 1% of abortions.
