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- Episiotomy

The evidence for the protective effect of episiotomy on OASIS is conflicting. Restrictive
episiotomy use is recommended over routine episiotomy. Mediolateral episiotomy should be

considered in instrumental deliveries. In addition, the mediolateral technique, which ensures that

the angle is 60 degrees away from the midline when the perineum is distended, is recommended.

- Perineal protection
The benefit of perineal protection is unclear even with the Ritgen manoeuvre (delivering

the fetal head, using one hand to pull the fetal chin from between the maternal anus and the

coccyx and the other on the fetal occiput to control speed of delivery). Nevertheless, the perineal

protection or “hand on” is preferred to “hands off” or “poised” in terms of reducing the incidence
of OASIS.

- Warm compression

The application of warm compresses on the perineum during the second stage of labour

effectively decreases the OASIS rate. Therefore, obstetrician-gynecologists and other obstetric
care providers can apply warm compresses to the perineum during pushing to reduce the

incidence of third-degree and fourth-degree lacerations.

- Perineal massage during antenatal period and in the second stage of labour

The data regarding the protective effect of perineal massage during the last month of
pregnancy are promising. The explanation is due to the more easily expandable perineal tissue

during vaginal birth. On the other hand, the protective effect of perineal massage in the second

stage of labour on OASIS is questionable.

Obstetric Anal Sphincter InjurieS (OASIS): Impact and prevention 72