A small percentage of abortions in the United States are performed in the second trimester. Patients should be informed of medical and surgical options.
Dr. Perry is a Fellow in Family Planning at the University of Illinois Hospital and Health Sciences System, Chicago.
Dr. Harwood is the Residency Program Director at Cedars-Sinai Medical Center Department of Obstetrics and Gynecology, Los Angeles, California.
Neither author has a conflict of interest to report regarding the content of this article.
Approximately 1.2 million induced abortions are performed each year in the United States; 8% occur in the second trimester of pregnancy and 1.3% occur at 21 weeks’ gestation or later (Figure).1 Medical advances have replaced high-morbidity procedures (such as intra-amniotic hypertonic saline and hysterotomy) with safer and more-effective methods including dilation and evacuation (D&E) and medical abortion (labor induction). Although modern methods of abortion in the second trimester have low morbidity overall, risks of second-trimester abortion are higher than those in the first trimester and increase with advancing gestational age.1
Second-trimester abortion also carries higher financial costs to individuals, medical institutions, and society. Second-trimester abortion remains a necessary procedure despite higher risks and costs compared to first-trimester procedures due to advances in antenatal diagnosis; decreased access to timely, early abortion care; and medical complications of pregnancy in the second trimester.
Counseling on both medical and surgical options for second-trimester termination is fundamental to preserving patient autonomy and supporting patient decision making.2 Compared to medical abortion by labor induction, surgical D&E is generally a shorter process performed under deeper anesthesia and is most often an outpatient surgery. Medical abortion is usually done on a labor and delivery unit, can be unpredictable in timing, and allows contact with the fetus if the patient wishes. When given the choice between these 2 methods, most women choose D&E, including for anomalous pregnancies.2
The vast majority of women have no long-term psychologic sequelae after abortion, but short-term grief may be considerable, particularly for those choosing to terminate a desired pregnancy.3 Resources for counseling should be made available before and after the abortion. Clinicians should be comfortable providing nondirective counseling for pregnancy options (abortion, adoption, parenthood), as well as the risks and benefits of both abortion procedures, with an understanding of special circumstances that may make one preferred over the other. Postabortal contraception has the public health benefit of decreasing repeat abortion.4 Contraception options should be discussed prior to the procedure, as described here.
Dilation and evacuation (D&E). In the United States, 95% of abortions in the second trimester occur by D&E.1 D&E involves preparation of the cervix with osmotic dilators or pharmacologic agents to safely achieve dilation adequate for passage of forceps into the uterine cavity to remove the products of conception. Cervical preparation may be done over hours or several days, depending on gestational age and clinical scenario.
Osmotic dilators have been shown to reduce the risk of cervical laceration.5 Two types of osmotic dilators are available in the United States: laminaria, which are made from dehydrated Laminaria japonica and L. digitata seaweeds, and Dilapan-S, which is a synthetic polyacrylate-based hydrogel. Either may be inserted into the cervical canal, and over the course of hours absorb cervical moisture and increase in diameter. Dilapan achieves maximum diameter at 6 hours, whereas laminaria continue to expand for 12 to 24 hours after placement. Although each Dilapan costs over $2 more than laminaria ($5.58 vs $3.25), approximately half the number are needed to achieve the same amount of cervical dilation provided by laminaria.6,7 A 2010 Cochrane review found no superiority of one type of osmotic dilator over the other.8 There are no published guidelines on the number of osmotic dilators needed or the time needed for cervical preparation, although it is recommended that as gestational age increases, a greater number of dilators be used for a longer time.9
Cervical preparation also can be achieved using pharmacologic agents, namely the prostaglandin E1 analogue misoprostol, which has cervical ripening properties in the second trimester similar to those for a term pregnancy.10 Although osmotic dilators have been shown to produce a greater degree of dilation than misoprostol, the procedure times and rates of complication in the early second trimester (14-16 wk) are equivalent.8 The advantages of cervical preparation with misoprostol compared to osmotic dilators include avoidance of an additional procedure, lower cost, no need for a trained provider, and a faster effect.
The Society of Family Planning (SFP) guidelines state that misoprostol can be used in lieu of osmotic dilators in gestations less than 16 weeks at low risk for cervical or uterine injury. Misoprostol can also be considered as an adjunct to osmotic dilators in patients over 19 weeks’ gestation because it may reduce the need for additional mechanical dilation.9 Although there are published trials on different protocols, no consensus exists on the optimal timing, route, and dosage of misoprostol as an adjunct to osmotic dilators.
The D&E procedure is most often performed under moderate (“conscious”) sedation, but it may be performed using minimal sedation to general anesthesia, or local or regional anesthesia. At the time of surgery the dilators are removed and the products of conception are removed with a combination of forceps and suction. Intraoperative ultrasound (U/S) decreases the rate of uterine perforation, at least in the training setting.11 Prophylactic antibiotics reduce the risk of infection in first-trimester abortion, and SFP recommends routine antibiotic prophylaxis before all surgical abortions in the first and second trimester.12 One effective regimen is 100 mg doxycycline prior to abortion and 200 mg after abortion.13 Induction of fetal demise is not routinely recommended prior to abortion because of the increased risk of maternal harm and lack of proven benefits.14
Labor induction. Labor induction in the second trimester is stimulation of uterine contractions to expel the fetus and placenta using medical agents; misoprostol is most commonly used in the United States. Misoprostol dosing for labor induction varies by trimester. Higher doses are needed in the second trimester compared with term pregnancies. The SFP guidelines recommend 400 mcg misoprostol every 3 hours as the most-efficient dose that limits side effects.15 Vaginal and sublingual routes of administration are more effective than oral, and limited evidence supports buccal administration.15-18 One randomized trial used 400 mcg buccal misoprostol as repeat doses after a vaginal loading dose; when compared to repeat vaginal doses of misoprostol, that regimen had equal induction-to-abortion times.18
The addition of mifepristone to the misoprostol regimen for induction increases effectiveness and decreases induction-to-abortion time. Mifepristone is a synthetic steroid that competitively binds to progesterone receptors, and also appears to increase myometrial sensitivity to misoprostol.19 Administration of mifepristone 24 to 48 hours before misoprostol decreases mean induction times by up to 45%, and it has been suggested that use of adjunctive mifepristone could make induction a day procedure.20
Abortion in the second trimester by medical or surgical means is safe and has a lower mortality rate than that of continued pregnancy.21 A Cochrane review found that major and minor complications were less common with D&E compared to labor induction (odds ratio 0.12).22 A randomized controlled trial comparing the 2 methods has not been feasible to date, partly because women favor choice over being randomized.23
Complications from D&E include cervical laceration (0%–1%), uterine perforation (0.25%–0.4%), hemorrhage (0.85%–2.1%), infection, and retained products of conception.9,24 Morbidity of D&E increases with increasing gestational age. D&E does not increase the risk of preterm delivery in future pregnancies.9,25 The most common complication of second-trimester medical abortion is retained placenta, which is estimated to occur at a rate of 15% to 50%.15 SFP guidelines do not recommend routine placental removal after a predefined period of time and expectant management for up to 4 hours has no serious adverse effects.15,26 Other complications of medical abortion include hemorrhage requiring transfusion (<1%), infection (2.6%), and failed abortion.27
Several common conditions can affect the procedure plan or preparation, including prior cesarean delivery, abnormal placentation, increasing gestational age, and obesity. One or more prior cesarean deliveries is not a contraindication to surgical or medical termination, or to misoprostol used as an adjunct to osmotic dilator placement. A history of 2 or more prior cesarean deliveries increases the risks of both surgical and medical abortion in the second trimester. In a retrospective review of almost 3000 D&Es, a history of 2 or more cesarean deliveries was associated with 7.4-fold increased odds of major complication, but no increase was associated with one prior cesarean.28 A meta-analysis estimated the risk of uterine rupture associated with labor induction after one cesarean delivery at 0.4%.29
For pregnancies complicated by placenta previa or accreta, surgical termination is recommended over labor induction. Placenta accreta poses similar risks in the second trimester as in a term pregnancy, and can be associated with massive hemorrhage. We recommend detailed preoperative planning and preparation for possible hemorrhage, including more invasive procedures, when abnormal placentation is suspected. Other special considerations for second-trimester abortion are described in the Table.28-33
Postabortion care should include assessments of emotional well being, physical recovery, and future childbearing plans. Follow-up in 1 to 4 weeks is believed to be appropriate, but it is not evidence-based.34 Because ovulation can occur as early as 3 weeks after abortion, however, contraception should be initiated as soon as possible after termination unless pregnancy is desired.35 Combined hormonal methods, progestin-only pills, and injectables can be initiated immediately, and have a US Medical Eligibility Criteria Category I rating (no restriction) for use post second-trimester abortion.36
Much research on postabortion contraception has focused on immediate postabortion placement of an intrauterine device (IUD). (See “Leveraging long-acting reversible contraceptives (LARCs)” in the December 2012 issue of Contemporary OB/GYN.) The US Medical Eligibility Criteria for Contraceptive Use states that the advantages of IUD placement after second-trimester abortion generally outweigh the risks.36 The main risk of IUD placement in the second trimester is an increased rate of expulsion compared to interval placement, which may be decreased by use of U/S guidance.37,38 The risks of perforation and infection are not increased with immediate placement.37 Proper fundal positioning can be ensured with use of intraprocedural U/S. Contraceptive implants may also be placed at the time of the procedure.36 Patients desiring to conceive again after termination of an anomalous pregnancy may benefit from preconception counseling with a genetic counselor or maternal-fetal medicine specialist.
D&E and labor induction are safe and effective modern methods of second-trimester abortion. When we provide patients with both options, most women choose D&E rather than labor induction. Having physicians trained in D&E procedures is crucial to providing timely and safe care for our patients.
To download a PDF of this patient education handout, go to www.contemporaryobgyn.net/after_D_and_E.pdf
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