Second-trimester abortion: Update on clinical and legal aspects

October 21, 2019

Although women face many obstacles to first-trimester abortion, challenges to second-trimester abortion are even greater.

Case studyJoanna is a 17-year-old G2P1 living in Garden City, Kansas who sought a pregnancy test after missed menses and learned that she was 11 weeks pregnant despite placement of an intrauterine device 9 months ago. She moved out of her parents’ home due to domestic violence and lives with her grandmother. They depend on Social Security, Medicaid and Joanna’s part-time job to raise her baby as she works to complete high school. Joanna talked extensively with her grandmother and decided to pursue an abortion. Due to the barriers she encountered (Table 1), Joanna eventually presented to a clinic in New Mexico at 19 weeks for her abortion and paid $2,000 for her care, plus travel costs and time missed from her job and school.

The case study here is not atypical for many women seeking second-trimester abortion, as barriers mount to abortion care access throughout the country. Women face many obstacles to first-trimester abortion; challenges to second-trimester abortion are even greater, with fewer trained and willing providers, increased costs, and gestational age limits. As of July 1, 2019, 17 states had “20-week” abortion bans.1 Access to abortion, including in the second trimester, is critical to maintaining women’s health and autonomy. The timing of a second-trimester abortion may be related to delays in care access, fetal anomalies, or health and life-threatening patient conditions. In this article, we discuss the epidemiology of second-trimester abortion, medical techniques including complex clinical scenarios, and the current status of abortion access in the United States.

Epidemiology
Second-trimester abortions account for only a small fraction of all abortions in the United States; as of 2015, 7.6% of all abortions occurred between 14 and 20 weeks and only 1.4% occurred at 21 weeks or more.2 Induced abortion is safer than childbirth, and complications of the procedure are very low even in the second trimester.3,4  While most abortions occur in the first trimester, women like Joanna who seek second-trimester abortion face obstacles such as transportation, financial difficulties, delayed diagnosis (of pregnancy and of fetal abnormalities), and lack of knowledge about how to access the desired procedure.5  

Abortion options
Second-trimester abortion can be performed via standard dilation and evacuation (D&E) or through medical induction with mifepristone and misoprostol. When reviewing the two options, most women prefer D&E.6,7  Few randomized studies directly compare induction to D&E because women are generally unwilling to be randomized; overall D&E is less painful and more acceptable than induction.7  
 

Dilation and evacuation
D&E is the most common method of second-trimester pregnancy termination in the United States, accounting for more than 98% of all such procedures and nearly 95% of all abortions after 21 weeks.2 The procedure can be safely performed in the outpatient setting with appropriately trained providers and staff; hospital care is not necessary for most low-risk patients.4 D&E comprises two steps: cervical preparation and uterine evacuation.  

The Society of Family Planning recommends cervical preparation in the second trimester to facilitate safe uterine evacuation.8 Cervical preparation can be accomplished with osmotic dilators, medications, or both in combination; the necessary amount of dilation depends on factors such as gestational age and parity.  Cervical preparation decreases rates of uterine perforation and cervical laceration, especially in later gestations.8

In the early second trimester, misoprostol, a synthetic prostaglandin E1 analog, administered the same day as the D&E is usually sufficient for cervical preparation. It induces uterine contractions and cervical softening. Following misoprostol administration, the cervix is mechanically dilated with dilators, such as Pratt or Hegar dilators at the discretion and preference of the physician, until dilation is adequate for safe uterine evacuation. Common misoprostol regimens include 400 or 600 mcg administered 1.5 to 4 hours prior to the procedure by vaginal, buccal, or sublingual route.8

As gestational age advances, cervical osmotic dilators either alone or in combination with misoprostol are required for adequate cervical dilation. Osmotic dilators or tents are small, thin rods that radially expand as they absorb fluid. The proximal end of the dilator is placed through the internal os with the distal end visible at the external os.  The most well-known osmotic dilator is the dehydrated sterilized seaweed Laminaria japonicum, commercially available in standard sizes. One or more Laminaria tents are retained at least 12 hours, usually overnight, to achieve full dilation. More Laminaria tents and serial sets of dilators may be needed for abortions at more advanced gestational ages. The synthetic hygroscopic dilator Dilapan-S expands more quickly and is used for same-day or multiple-day cervical preparation. Dilapan-S dilators are more expensive than Laminaria tents, although fewer Dilapan-S are needed to accomplish the same cervical dilation. The choice and number of dilators is at the discretion of the surgeon as no minimum number, standard or preferred combination of osmotic dilators has been established for any gestational age.8

Mifepristone, an antiprogestogen that causes cervical softening and dilation, is a potent addition to cervical preparation. A combination of mifepristone and osmotic dilators is often used in the late second trimester; beyond 19 weeks, mifepristone 200 mg orally at the time of dilator placement increases ease of the D&E procedure.9 Mifepristone is better tolerated than adjunctive misoprostol, which may cause pain, fever, and chills.9 Although the complication of infection with surgical abortion is low, antibiotic prophylaxis reduces the risk; the American College of Obstetricians and Gynecologists recommends a single dose of doxycycline 200 mg orally at the time of surgical abortion, typically administered when dilators are placed.10

In case you missed it: Three steps to provide mifepristone

D&E is performed after adequate cervical dilation is achieved, either the same day or up to 2 days later, depending on the extent of cervical preparation needed. A large suction cannula, usually a size 14 or 16 at and after 16 weeks’ gestation, is used to drain the amniotic fluid and the pregnancy tissue is removed using a combination of instruments and suction. Bierer or other modified ovum forceps facilitate uterine evacuation. Risk of significant bleeding during D&E is reduced by adding vasoconstrictive agents such as vasopressin to a paracervical block and by administering oxytocin 30 units intravenously over 15 minutes during the procedure.11,12 Routine intraoperative ultrasound guidance decreases rates of uterine perforation, especially in the training setting.13

Medical induction
Just as with use of mifepristone for cervical preparation for D&E, pretreatment with mifepristone 200 mg orally 24 to 48 hours prior to induction prepares the cervix and improves success rates of medical abortion in the second trimester. Compared with simultaneous administration or placebo, mifepristone pretreatment leads to much shorter (up to 50%) induction times; 95% of women deliver within 24 hours of starting the induction.14,15 Placement of cervical osmotic dilators at the time of induction does not shorten overall procedure time.16

Misoprostol is the most commonly used medication for second-trimester induction abortion. While several regimens have been studied, a frequent misoprostol dosing interval of every 3 hours shortens the overall induction time; 400 mcg appears to be the minimum effective dose. Vaginal and sublingual routes of misoprostol are superior to oral administration.16 Reported rates of intervention for bleeding or retained placenta vary; with these evidence-based medication regimens, the rate of retained placenta is as low as 6%.15

Special considerations Pre-procedure medications for fetal demise
It is not medically necessary to induce fetal demise prior to a second-trimester abortion.17,18 Feticide does not decrease D&E procedure time or complications.19,20 Digoxin injection prior to D&E is associated with increased rates of infection, hospital admission, and spontaneous expulsion.20 For induction abortion, limited evidence suggests feticide injection may shorten induction-to-delivery time.17,21 When asked, patients report discomfort and difficulty with feticide injections, but also reassurance.22

Digoxin or potassium chloride may be administered as a feticide injection. Complications with digoxin are unusual; when shared decision-making results in use of digoxin, it is administered as a dose of 1 to 2 mg injected into the fetus or into the amniotic fluid on the first day of osmotic dilator placement. Intrafetal digoxin injection is more likely to cause fetal asystole within 24 hours than intra-amniotic injection; doses lower than 1 mg are less likely to cause asystole.23,24 Potassium chloride is more commonly used for selective fetal reduction and must be administered directly into the umbilical cord or into a fetal cardiac chamber, requiring more technical skill to administer than digoxin. The dose of potassium chloride required for effectiveness varies between 6 and 20 mEq.17

 

Prior uterine surgery
History of cesarean delivery is one of the most common conditions potentially complicating second-trimester abortion. The placenta should be evaluated for all women with prior uterine surgery and specialist referral is indicated in cases where there is concern for morbidly adherent placenta. D&E is safe for women with prior uterine surgery and normal placentation. Two or more cesarean deliveries increases the risk of major complications with D&E compared with one or no cesareans.25

Uterine rupture with second-trimester induction abortion with misoprostol is a rare event, with a risk of less than 0.5% in women with one prior cesarean delivery compared with less than 0.1% with no uterine surgery.26 Risk of uterine rupture for women with two or more cesarean deliveries (2.5%) is significantly increased compared with no prior uterine surgery.26 For women with a history of one or more cesarean deliveries, risk of retained placenta and of needing blood transfusion is also increased during induction abortion.26 Regimens for misoprostol dosing can be modified based on gestational age, with use of higher doses early in the second trimester and lower doses between 24 and 28 weeks.

 

Spontaneous fetal demise and pPROM
Pregnancies complicated by spontaneous intrauterine fetal demise (IUFD) for longer than 4 weeks or measuring greater than 20 weeks are at increased risk of hemorrhage and/or transfusion.27,28 D&E is safer than labor induction for IUFD in the second trimester; women should be offered both methods when available.28,29 Coagulation studies do not appear to predict risk of hemorrhage, although research is limited.27

For women with previable prelabor rupture of membranes (PROM), cervical preparation for D&E is often easier because membrane rupture may cause prostaglandin release.  Both D&E and induction are safe for women with previable PROM. Induction-to-delivery time is shorter for women with previable PROM and with IUFD.30,31 In one large cohort, women who underwent D&E for fetal anomalies, IUFD, or previable PROM were less likely to have a subsequent preterm birth (6.9%) than women who chose induction (30.2%).32

Abortion access in the United States
The 1973 Roe v. Wade Supreme Court decision established the constitutional right to abortion. In 1992, the Supreme Court allowed states to create restrictions that did not place an “undue burden” on women’s access to abortion. Since Roe, 1200 restrictions have been enacted; recently the pace of abortion restrictions has accelerated, and the nature of the restrictions more severely curtails access.33 Nearly 60% of US women live in a state with significant abortion restrictions.33 As Joanna found (Table 1), many restrictions target the woman seeking abortion.

Other restrictions focus on limiting abortion provision, including facility and provider requirements. A case study of the impact of abortion provision restrictions occurred in Texas with the passage of House Bill 2 (HB2) in 2012. HB2, an omnibus law, required admitting privileges at a nearby hospital for physicians providing abortions and required clinics to meet ambulatory surgical center standards for all abortions, including medication abortions. HB2 also banned most abortions after 20 weeks and imposed medically unnecessary restrictions on medication abortion. The impact was dramatic: by 2014, only 19 of the previous 43 clinics remained open. Although key parts of HB2 were reversed by a Supreme Court decision in 2016, the damage was done; few closed clinics have been able to reopen. 

 

Restrictions targeting patients, providers, and facilities have already created significant barriers that reduce abortion access in many states. Furthermore, the true intent of recent aggressive anti-abortion legislation is less likely than in the past to be cloaked as improving patient safety; current proponents of restrictive legislation articulate the purpose of eliminating legal abortion. Illegal abortion is highly associated with maternal mortality, both in the United States pre Roe v Wade and throughout the world where abortion is illegal.34 It is no surprise that our leading US medical journals have published cautionary editorials sounding the alarm about the ramifications of gutting or reversing Roe v Wade.33,35 We echo these calls to action and strongly support continued access to safe, legal, and equitable abortion, including evidence-based patient-centered second-trimester abortion care.

Disclosures:

The authors report no potential conflicts of interest with regard to this article.

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