Mediolateral episiotomy may reduce sphincter injury

Mediolateral episiotomy was linked to fewer anal sphincter tears in first vaginal operative births.
*Secondary cohort analysis; Level 2b (OCEBM).

Citation

Doyle AA, Allshouse AA, Metz TD, Speranza RJ. Episiotomy and Anal Sphincter Injury During Operative Vaginal Delivery in a U.S. Cohort. Obstetrics & Gynecology. 2026;00:1-9. doi:10.1097/AOG.0000000000006426

Background

Operative vaginal delivery and first vaginal birth increase the risk of severe perineal tears involving the anal sphincter. Episiotomy may help or harm depending on incision type.

Patients

5,277 term, head-first, singleton operative vaginal deliveries from 25 U.S. hospitals. Excluded preterm birth, breech, multiple gestation, no labor, no operative vaginal delivery, or missing exposure/outcome data.

Intervention

Midline or mediolateral episiotomy during vacuum- or forceps-assisted vaginal delivery.

Control

No episiotomy.

Outcome

Third- or fourth-degree perineal tear involving the anal sphincter.

Follow-up Period

Delivery hospitalization only.

Results

Overall sphincter injury incidence was 20.1%. Episiotomy overall was associated with higher adjusted odds: adjusted odds ratio 1.45 (95% CI 1.25 to 1.67).

Subgroup and episiotomy type Tear rate Adjusted odds ratio NNT or NNH
No prior vaginal birth, forceps, mediolateral 22.7% vs 36.1% 0.54 (95% CI 0.35 to 0.83) NNT 8
No prior vaginal birth, vacuum, mediolateral 11.2% vs 15.7% 0.60 (95% CI 0.38 to 0.96) NNT 23
No prior vaginal birth, vacuum, midline 29.2% vs 15.7% 2.24 (95% CI 1.81 to 2.77) NNH 8
Prior vaginal birth, vacuum, midline 17.5% vs 3.8% 4.06 (95% CI 2.54 to 6.50) NNH 8

NNT: number needed to treat. NNH: number needed to harm.

Analysis used complete cases; 4% were excluded. No episiotomy reflects current usual U.S. practice more closely than routine episiotomy.

Limitations

Observational design cannot prove causation. Episiotomy angle, length, clinician skill, hospital site, perineal support, and long-term pain or sexual outcomes were unavailable. Data were from 2008-2011.

Funding

No direct funding reported; federal network data; industry conflicts disclosed.

Clinical Application

Avoid midline episiotomy with vacuum delivery; consider mediolateral episiotomy selectively for first vaginal operative births after informed consent.