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Cervical Ripening in the Outpatient Setting

Systematic Review

This report is available in PDF and XLSX only (Systematic Review [4.77 MB]; Evidence Summary [367 KB]; Appendix E-1. Data Abstraction of Study Characteristics [XLSX, 42.4 KB]; Appendix E-2. Data Abstraction of Outcomes [XLSX, 54.5 KB]; Appendix G. Risk of Bias Assessments [XLSX, 16.3 KB]). For additional assistance, please contact us.

Main Points

  • The highest strength of evidence for outcomes of outpatient cervical ripening found in this report was low, with several important outcomes having insufficient evidence. A rating of low-strength evidence means that there is low certainty in the magnitude or direction of the findings, and that future studies could change the conclusions.
  • Low-strength evidence suggested that outpatient cervical ripening with dinoprostone (intravaginal insert or intracervical gel) or single-balloon catheters (30–50 ml fill) were not significantly different for cesarean delivery, fetal/neonatal infection with dinoprostone and maternal infection, birth trauma or shoulder dystocia with single-balloon catheters in comparison with the same intervention in the inpatient setting.
  • Low-strength evidence suggested that cesarean delivery and postpartum hemorrhage were not significantly different between cervical ripening with catheters (double-balloon or single-balloon) in the outpatient setting and dinoprostone in the inpatient setting.
  • The evidence on outpatient cervical ripening with misoprostol, double-balloon catheters, or hygroscopic dilators was insufficient.
  • Low-strength evidence suggested that the risk of cesarean delivery with dinoprostone intracervical gel 2.5 mg versus 5.0 mg, and with silicone versus latex single-balloon catheters in the outpatient setting was not significantly different. Evidence was insufficient to draw conclusions on other outcomes or other direct comparisons of interventions.
  • Low-strength evidence suggested that in the outpatient setting, the risk of cesarean delivery with prostaglandins was not significantly different than placebo, expectant management, and membrane sweeping. The incidence of meconium aspiration syndrome, shoulder dystocia, and uterine infection, primarily with dinoprostone, were not significantly different than placebo.
  • There was no evidence comparing different mechanical methods with each other, with membrane sweeping or with expectant management in the outpatient setting.
  • For all comparisons, there was insufficient evidence on time from admission to vaginal birth, perinatal mortality, fetal/neonatal intracranial or subgaleal hemorrhage, hypoxic-ischemic encephalopathy, and maternal hemorrhage requiring transfusion.
  • Comparative evidence on fetal surveillance for cervical ripening with a prostaglandin was not found.

Structured Abstract

Objectives. To assess the comparative effectiveness and potential harms of cervical ripening in the outpatient setting (vs. inpatient, vs. other outpatient intervention) and of fetal surveillance when a prostaglandin is used for cervical ripening.

Data sources. Electronic databases (Ovid® MEDLINE®, Embase®, CINAHL®, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews) to July 2020; reference lists; and a Federal Register notice.

Review methods. Using predefined criteria and dual review, we selected randomized controlled trials (RCTs) and cohort studies of cervical ripening comparing prostaglandins and mechanical methods in outpatient versus inpatient settings; one outpatient method versus another (including placebo or expectant management); and different methods/protocols for fetal surveillance in cervical ripening using prostaglandins. When data from similar study designs, populations, and outcomes were available, random effects using profile likelihood meta-analyses were conducted. Inconsistency (using I2) and small sample size bias (publication bias, if ≥10 studies) were assessed. Strength of evidence (SOE) was assessed. All review methods followed Agency for Healthcare Research and Quality Evidence-based Practice Center methods guidance.

Results. We included 30 RCTs and 10 cohort studies (73% fair quality) involving 9,618 women. The evidence is most applicable to women aged 25 to 30 years with singleton, vertex presentation and low-risk pregnancies. No studies on fetal surveillance were found. The frequency of cesarean delivery (2 RCTs, 4 cohort studies) or suspected neonatal sepsis (2 RCTs) was not significantly different using outpatient versus inpatient dinoprostone for cervical ripening (SOE: low). In comparisons of outpatient versus inpatient single-balloon catheters (3 RCTs, 2 cohort studies), differences between groups on cesarean delivery, birth trauma (e.g., cephalohematoma), and uterine infection were small and not statistically significant (SOE: low), and while shoulder dystocia occurred less frequently in the outpatient group (1 RCT; 3% vs. 11%), the difference was not statistically significant (SOE: low). In comparing outpatient catheters and inpatient dinoprostone (1 double-balloon and 1 single-balloon RCT), the difference between groups for both cesarean delivery and postpartum hemorrhage was small and not statistically significant (SOE: low). Evidence on other outcomes in these comparisons and for misoprostol, double-balloon catheters, and hygroscopic dilators was insufficient to draw conclusions.

In head to head comparisons in the outpatient setting, the frequency of cesarean delivery was not significantly different between 2.5 mg and 5 mg dinoprostone gel, or latex and silicone single-balloon catheters (1 RCT each, SOE: low). Differences between prostaglandins and placebo for cervical ripening were small and not significantly different for cesarean delivery (12 RCTs), shoulder dystocia (3 RCTs), or uterine infection (7 RCTs) (SOE: low). These findings did not change according to the specific prostaglandin, route of administration, study quality, or gestational age. Small, nonsignificant differences in the frequency of cesarean delivery (6 RCTs) and uterine infection (3 RCTs) were also found between dinoprostone and either membrane sweeping or expectant management (SOE: low). These findings did not change according to the specific prostaglandin or study quality. Evidence on other comparisons (e.g., single-balloon catheter vs. dinoprostone) or other outcomes was insufficient. For all comparisons, there was insufficient evidence on other important outcomes such as perinatal mortality and time from admission to vaginal birth. Limitations of the evidence include the quantity, quality, and sample sizes of trials for specific interventions, particularly rare harm outcomes.

Conclusions. In women with low-risk pregnancies, the risk of cesarean delivery and fetal, neonatal, or maternal harms using either dinoprostone or single-balloon catheters was not significantly different for cervical ripening in the outpatient versus inpatient setting, and similar when compared with placebo, expectant management, or membrane sweeping in the outpatient setting. This evidence is low strength, and future studies are needed to confirm these findings.

Journal Citation

McDonagh M, Skelly A, Tilden E, et al. Outpatient cervical ripening: a systematic review and meta-analysis. Obstet Gynecol. 2021 March 22. [Epub ahead of print.] DOI: 10.1097/AOG.0000000000004382.


McDonagh M, Skelly AC, Hermesch A, Tilden E, Brodt ED, Dana T, Ramirez S, Fu R, Kantner SN, Hsu F, Hart E. Cervical Ripening in the Outpatient Setting. Comparative Effectiveness Review No. 238. (Prepared by the Pacific Northwest Evidence-based Practice Center under Contract No. 290-2015-00009-I for the Agency for Healthcare Research and Quality and the Patient-Centered Outcomes Research Institute.) AHRQ Publication No. 21-EHC011. PCORI Publication No. 2020-SR-03. Rockville, MD: Agency for Healthcare Research and Quality; March 2021. DOI: 10.23970/AHRQEPCCER238. Posted final reports are located on the Effective Health Care Program search page.