Key messages
• Both surgery and medicines may be safe and effective when used to end pregnancy in the second trimester.
• Future studies that focus on outcomes important to the patient, such as pain, are needed.
How is abortion performed in the second trimester?
Abortion after three months of pregnancy (second trimester) can be done by surgery or with medicines. We wanted to know which method is the safest and most effective.
What did we want to find out?
We wanted to know if abortion by surgery or with medicines works better to:
• complete the abortion with the planned method;
• prevent heavy bleeding and injury to the cervix, vagina, and uterus;
• reduce pain;
• increase patient satisfaction.
What did we do?
We looked for studies that compared surgery to medicines used for abortion in the second trimester. We summarized the findings and rated how confident we are in the results.
What did we find?
We found three studies that compared abortion with a surgical procedure called dilation and evacuation (where the person is administered treatment to open the cervix, and then the contents of the uterus are removed) to abortion using medicines (mifepristone and misoprostol). The studies were conducted in South Asia (141 participants), England (122 participants), and the United States (18 participants).
Both surgery and medicines may be safe and effective when used to end pregnancy in the second trimester. While both methods resulted in completion of the abortion in nearly all cases, medicines may increase the risk of incomplete abortion. Medicines may result in a slightly increased risk of bleeding. Serious heavy bleeding was rare. We do not know enough about other aspects of the patient's experience, such as pain, and need more studies.
What are the limitations of the evidence?
We have little to very low confidence in the evidence. Complications were very rare and uncommon. There was a small number of studies, and the interventions differed a lot across studies. We do not know enough about other aspects of the patient experience and need more studies.
How up-to-date is this evidence?
The evidence is current to November 2023.
Read the full abstract
Understanding the relative benefits and harms of surgical versus medical methods for second-trimester abortion is essential for guiding clinical practice across diverse settings and patient populations. This review evaluates differences in outcomes and patient experiences to support informed counseling and care. It updates a previous version published in 2008.
Objectives
To compare the benefits and harms of surgical and medical methods of induced abortion in the second trimester (i.e. at or after 13 weeks' gestation).
Search strategy
We identified trials using CENTRAL (Ovid EBM Reviews), MEDLINE ALL (Ovid), Embase.com, LILACS, Scopus, and Google Scholar on 29 November 2023. We also searched the reference lists of identified studies, relevant review articles, book chapters, and conference proceedings for additional, previously unidentified studies. We contacted experts in the field for information on other published or unpublished research.
Selection criteria
Randomized trials comparing surgical abortion by vacuum aspiration or dilation and evacuation (D&E) to medical abortion with mifepristone and misoprostol in the second trimester of pregnancy.
Data collection and analysis
We assessed the validity of each study using Cochrane methods. We contacted investigators for additional information regarding trial conduct or outcomes as required. Some outcomes were consistently reported across multiple studies and could be combined for meta-analysis. The primary outcome of interest was abortion completed with the intended method (defined as fetal expulsion).
Main results
We included three studies (281 participants). The studies were conducted in Nepal (n randomized = 141), England (n randomized = 122), and the United States (n randomized = 18) and included participants with pregnancy durations ranging from 12 weeks to 19 weeks and 6 days. We used GRADE to assess the certainty of evidence.
Abortion completed with the intended method (defined as fetal expulsion) occurred for nearly all trial participants. There may be no difference between surgical and medical methods, although the evidence for this outcome is very uncertain (risk ratio (RR) 0.99, 95% confidence interval (CI) 0.96 to 1.02; 3 trials; 269 participants). Incomplete abortion requiring an additional procedure or intervention (immediate or delayed) may occur less often with surgical abortion (RR 0.19, 95% CI 0.07 to 0.53; 3 trials; 269 participants), but the evidence is very uncertain.
Hemorrhage requiring blood transfusion may occur less often with surgical abortion, but the evidence is very uncertain as the outcome occurred infrequently (RR 0.29, 95% CI 0.07 to 1.12; 3 trials; 269 participants). There may be less bleeding with surgical abortion than with medical abortion based on a measure of total blood loss (difference in mean estimated blood loss (mL) −59.80, 95% CI −65.21 to −54.39; 1 trial; 141 participants; low certainty evidence). At two weeks post-abortion, medical abortion may be associated with more bleeding reported by participants as heavier than a menstrual period than surgical abortion (RR 0.10, 95% CI 0.01 to 0.76; 1 trial; 56 participants), but the evidence is very uncertain.
One cervical laceration was reported in the surgical abortion group across the three studies, therefore the evidence for the effect of surgical versus medical abortion on the risk of injury to the cervix, vagina, or uterus is very uncertain.
Patient-reported pain scores may be lower with surgical abortion compared with medical abortion, but the evidence is very uncertain (mean difference in pain score on visual analogue scale −2.20, 95% CI −3.81 to −0.59; 1 trial; 56 participants). Patient satisfaction (overall) with the assigned method appeared similar (2 trials; 83 participants), but the evidence is very uncertain, and the data could not be pooled due to inconsistent outcome measures.
Authors' conclusions
Comparative evidence on second-trimester surgical abortion (vacuum aspiration or D&E) versus medical abortion (mifepristone and misoprostol) was limited, drawn from three studies with varying practices and reported outcomes. While allocation to interventions was robust, none of the studies were blinded. Additionally, concerns about enrollment and incomplete outcome reporting may have influenced the results.
While both methods resulted in expulsion of the fetus in nearly all cases, there is very low certainty evidence that medical abortion may increase the risk of incomplete abortion and interventions to remove the placenta. The uncertainty was due to variations in clinical protocols and interventions conducted during the abortion process for placental removal with medical abortion. Low certainty evidence suggests that medical abortion results in a slightly increased risk of bleeding, defined as mean estimated blood loss (mL). Serious hemorrhage that required transfusion was rare, and differences between groups may have little to no effect on the outcome, but the evidence is very uncertain.
More studies using consistent protocols and measures (such as the STAR and MARE guidelines) are needed. Additionally, research that focuses on the patient's experience and to inform counseling should be considered.
