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Episiotomy in vacuum extraction, do we cut the levator ani muscle? A prospective cohort study


Introduction and hypothesis

Vaginal delivery may lead to levator ani muscle (LAM) injury or avulsion. Episiotomy may reduce obstetric anal sphincter injury in operative vaginal delivery, but may increase the risk of LAM injury. Our aim was to assess whether lateral episiotomy in vacuum extraction (VE) in primiparous women causes LAM injury.


A prospective cohort study of 58 primiparous women with episiotomy nested within an ongoing multicenter randomized controlled trial of lateral episiotomy versus no episiotomy in VE (EVA trial) was carried out in Sweden. LAM injury was evaluated using 3D endovaginal ultrasound 6–12 months after delivery and Levator Ani Deficiency (LAD) score. Episiotomy scar properties were measured. Characteristics were described and compared using Chi-squared tests. We stipulated that if a lateral episiotomy cuts the LAM, ≥50% would have a LAM injury. Among those, ≥50% would be side specific. We compared the observed prevalence with a test of one proportion.


Twelve (20.7%, 95% CI 10.9–32.9) of 58 women had a LAD (p < 0.001, compared with the stipulated 50%). Six (50.0%, 95% CI 21.1% to 78.9%) of 12 women had a LAD on the episiotomy side, including those with bilateral LAD (p = 1.00). Two (16.7%, 95% CI 2.1% to 48.4%) of 12 women had a LAD exclusively on the episiotomy side (p = 0.02).


There was no excessive risk of cutting the LAM while performing a lateral episiotomy. LAD was not seen in women with episiotomies shorter than 18 mm.

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We are deeply grateful to the women participating in the EVA trial and the obstetric staff who have contributed to the recruitment of study participants. We especially thank our research midwives Helen Fagraeus and Annelie Wikström, Danderyd Hospital, Stockholm, and Irina Sylve, Akademiska Hospital, Uppsala, Sweden.


This study was partly funded by the Swedish Research Council (grant number 2016-00526) and the Uppsala-Örebro Research Council (grant number RFR-939428).

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Authors and Affiliations



V. Ankarcrona: project development, data collection and analyses, result analyses, manuscript writing and editing; S. Karlström: project development, data collection and analyses, manuscript writing; S. Sylvan: result analyses, language editing, manuscript editing; M. Starck: data analyses, result analyses, manuscript editing; M. Jonsson: data collection, result analyses, manuscript editing; S. Brismar Wendel: project development, data collection and analyses, manuscript writing and editing. All authors approved the final version of the manuscript.

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Correspondence to Victoria Ankarcrona.

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Ankarcrona, V., Karlström, S., Sylvan, S. et al. Episiotomy in vacuum extraction, do we cut the levator ani muscle? A prospective cohort study. Int Urogynecol J (2022).

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  • Episiotomy
  • Lateral episiotomy
  • Levator ani deficiency score
  • Levator ani muscle injury
  • 3D endovaginal ultrasound
  • Vacuum extraction