Episiotomy in Vacuum-Assisted Vaginal Deliveries: Balancing Risk and Benefit

A Canadian cohort study found that episiotomy's effect on obstetric anal sphincter injury (OASI) risk in vacuum-assisted vaginal deliveries varies by clinical context — supporting selective use rather than blanket policy. The retrospective cohort analysis did not show a higher overall OASI risk with episiotomy across the study population, a finding that challenges one-size-fits-all episiotomy policies for operative vaginal births.

Episiotomy has long been used inconsistently to try to prevent severe perineal trauma during operative vaginal births. A controlled incision can redirect tensile forces and limit direct extension into the anal sphincter, though prior scarring or more resilient tissue may blunt any protective effect.

Across the cohort, episiotomy during vacuum-assisted delivery was not significantly associated with OASI. The analysis showed lower OASI risk with episiotomy in nulliparous patients and when the total second stage was prolonged, while parous individuals experienced a higher associated OASI risk. As an observational study, the findings remain susceptible to confounding by indication and residual bias despite adjusted analyses.

The subgroup signals have operational implications: anticipate episiotomy decisions based on parity and second-stage duration when planning vacuum-assisted births. Teams should ensure clear documentation of indications, include shared decision points when feasible, and provide targeted training on incision technique. Local protocol alignment and prospective monitoring of OASI rates will help assess any practice change.

Key Takeaways:

• What’s new: The Canadian cohort study shows episiotomy was not linked to higher overall OASI risk in vacuum-assisted deliveries, but effects differ by subgroup.
• Who’s affected: Nulliparous patients and those with a prolonged second stage appear most likely to derive protective benefit from episiotomy in this setting.
• What changes next: Expect more selective episiotomy decision-making, focused training on technique, and prospective monitoring of OASI after operative vaginal births.