Digital versus speculum-based balloon catheter insertion for labor induction: a systematic review and meta-analysis

OBJECTIVES: Induction of labor is commonly undertaken when ongoing pregnancy poses a risk to either the mother or fetus. Often cervical preparation is required with mechanical methods increasingly popular due to their improved safety. This study evaluates the efficacy, safety, and acceptability of digital versus speculum-based balloon insertion for cervical preparation, aiming to identify gaps and inform future research. DATA SOURCE: PubMed, Ovid MEDLINE, EMBASE, and Scopus were searched from database inception until 30 June 2023. STUDY ELIGIBILITY CRITERIA: Included studies were randomized controlled trials comparing digital versus speculum-based insertion of catheterrelated balloons for labor induction in individuals with viable singleton pregnancies, in both inpatient and outpatient settings, written in English. Exclusions included studies not using cervical balloons, comparisons to nonballoon methods, nonhuman studies, and nonprimary literature like guidelines, reviews, commentaries, and opinion pieces. METHODS: Title and abstract screening were performed by 4 authors. Full-text articles were assessed against inclusion criteria. Selection was agreed upon by consensus among 3 authors, with a fourth consulted for disputes. The risk of bias was assessed using the Cochrane Risk of Bias Tool 2.0 for randomized trials. A meta-analysis was also performed. RESULTS: Out of 3397 studies, 4 met the inclusion criteria, all being randomized controlled trials with some concerns in at least one domain but no high risk of bias. Two studies found digital insertion significantly less painful than speculum-based insertion (P<.001), while one reported no difference (P=.72). Maternal satisfaction was comparable, with one study favoring digital insertion (P=.011). Meta-analysis findings for other outcome measures suggest no difference between speculum or digital insertion. However, due to substantial heterogeneity, findings for procedural time, time from induction to delivery, and epidural rate should be cautiously interpreted. CONCLUSIONS: Digital insertion for cervical preparation appears associated with reduced pain and higher patient acceptability compared to speculum-based insertion. Additionally, efficacy and safety were comparable, indicating it is a preferable option for clinical use. There was no difference in other procedural, obstetric, or neonatal outcomes, however, more rigorous research employing standardized outcome measures is needed to facilitate a clinically meaningful interpretation.