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Objectives: The angle at which a mediolateral episiotomy is incised is critical to the risk of obstetric anal sphincter injuries (OASIS). When a mediolateral episiotomy is incised at least 60 degrees from the midline it is protective to the anal sphincter. The objective of our study was to investigate how accoucheurs described and depicted a mediolateral episiotomy.

Study design: One hundred doctors and midwives were invited to complete an interview-administered questionnaire in a district general hospital in the United Kingdom over a 10-month period commencing in August 2012. Accoucheurs were asked to describe the angle at which they would cut a mediolateral episiotomy, and to depict this on a pictorial representation of the perineum. The angle drawn was calculated by an investigator blinded to the participant’s initial description of a mediolateral episiotomy.

Results: Sixty-one midwives and 39 doctors participated. Doctors and midwives stated they would perform a mediolateral episiotomy at an angle of 45 degrees from the midline, but midwives depicted episiotomies 8 degrees closer to the midline (37.3 degrees vs. 44.9 degrees, p = 0.013) than they described. Seventy-six percent of accoucheurs had undergone formal training in how to perform a mediolateral episiotomy, but this had no impact on their clinical practice. Accoucheurs who had been supervised for ten episiotomies before independent practice performed them in keeping with the angle they described.

Conclusions: Doctors and midwives are unaware of the appropriate angle (60 degrees) at which a mediolateral episiotomy should be incised at to minimise obstetric anal sphincter injury. The correct angle should be emphasised to accoucheurs to minimise the risk of anal sphincter damage. In addition midwives depict episiotomies that are significantly more acute than they describe. Accoucheurs should also perform at least 10 episiotomies under supervision prior to independent practice. Training programmes should be devised and validated to improve visual measurement of the episiotomy incision angle at crowning. Consideration should also be given to the development of novel surgical devices that help the accoucheur to perform a mediolateral episiotomy accurately. Crown Copyright (C) 2013 Published by Elsevier Ireland Ltd. All rights reserved.