Cervical priming before surgical abortion between 14 and 24 weeks: a systematic review and meta-analyses for the National Institute for Health and Care Excellence-new clinical guidelines for England.

OBJECTIVE

This study aimed to determine the optimal cervical priming regimen before surgical abortion between 14 and 24 weeks' gestation.

DATA SOURCES

Embase, MEDLINE, and the Cochrane Library were searched for publications up to February 2020. Experts were consulted for any ongoing or missed trials.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials, published in English after 1985, that compared (1) mifepristone, misoprostol, and osmotic dilators against each other, alone or in combination; (2) different doses of mifepristone and misoprostol; (3) different intervals between priming and abortion; or (4) different routes of administration of misoprostol were included.

METHODS

Risk of bias was assessed using the Cochrane Collaboration checklist for randomized controlled trials, and data were meta-analyzed in Review Manager 5.3. Dichotomous outcomes were analyzed as risk ratios using the Mantel-Haenszel method, and continuous outcomes were analyzed as mean differences using the inverse variance method. Fixed effects models were used when there was no significant heterogeneity (I<50%), random effects models were used for moderate heterogeneity (I≤50% and <80%), and evidence was not pooled when there was high heterogeneity (I≥80%). Subgroup analyses were undertaken based on parity where available. The overall quality of the evidence was assessed using Grades of Recommendation Assessment, Development, and Evaluation.

RESULTS

A total of 15 randomized controlled trials (N=2454) were included and showed decreased difficulty of procedure and/or increased cervical dilation and decreased patient acceptability with regimens that included dilators compared with those that did not include dilators; increased preoperative expulsion of the pregnancy with sublingual misoprostol and mifepristone compared with sublingual misoprostol alone; increased difficulty of procedure with dilators and misoprostol compared with dilators and mifepristone; decreased difficulty of procedure with dilators and mifepristone compared with dilators alone; and increased cervical dilation when dilators were placed the day before abortion compared with the same day.

CONCLUSION

Considered alongside clinical expertise, the published data support the use of osmotic dilators, misoprostol, or mifepristone before abortion for pregnancies at 14 to 16 weeks' gestation; osmotic dilators or misoprostol for pregnancies at 16 to 19 weeks' gestation; and osmotic dilators alone or with mifepristone for pregnancies at 19 to 24 weeks' gestation. The effectiveness of pharmacologic agents alone beyond 16 weeks' gestation and the optimal timing of dilator placement remain important questions for future research.