From 2000 to 2012, the rate of obstetric anal sphincter injuries (OASIS) in England tripled from 1.8% to 5.9%, in primiparous women (1). The Royal College of Obstetricians and Gynaecologists guidelines state that mediolateral episiotomy in instrumental deliveries (where indicated); manual perineal protection at crowning and warm compression in the second stage can prevent OASIS. Additionally, all women delivering vaginally should have a digital rectal examination (DRE- female) to identify isolated, rectal buttonhole tears (2). 

In response to rates rising nationally, a prospective, observational audit of 41 deliveries was completed at our Trust in 2016 to identify areas where practice could be improved. This audit highlighted low rates of manual perineal protection and DRE- female post-delivery by midwives. In 2017, the Trust commenced 'PRactical Obstetric Multi-Professional Training' to increase OASIS preventative measures, amongst other Obstetrics emergencies and outcomes. To establish if this training had improved practice, a re-audit was completed in 2019. 

The aim of this audit was to assess changes in practice and areas where OASIS preventative measures can be implemented.

A prospective audit was completed from September to December 2019; all cases were observed in the Consultant lead unit. All deliveries included were observed from during the second stage, until the end of the third stage of labour. The clinician leading the delivery (midwife or doctor) was unaware of the data the observer was collecting. The pro forma collected information on parity, ethnicity, gestation, birthweight, previous OASIS, delivery position, mode of delivery, type of episiotomy, use of manual perineal protection, use of warm compression and DRE- female post-delivery.

Of the fourteen deliveries, eleven were led by a midwife throughout and three involved a doctor near the end, for instrumentation. They consisted of six primiparous and eight multiparous women. Their gestation ranged from 30+3 to 42+0 weeks and the birthweight ranged from 1400 to 4100 grams. In the 14 cases (100%), good manual perineal protection was used compared to only 24 out of 41 cases (58.5%) in the 2016 audit. The use of warm compression was used in two cases in this audit and no cases in 2016. In both audits, episiotomy was medio-lateral in all cases where it was required (fifteen cases in 2016 and three in 2019). There was 100% completion of a DRE- female by the doctor after intervening for instrumentation, in both the 2016 and 2019 audits. Of the remaining deliveries (completed entirely by a midwife) there was a DRE- female post-delivery in 16 of the 26 cases (61.5%) in 2016 and in 6 of the 11 cases (54.5%) in 2019.

Both the 2016 and 2019 audits are limited by their small number of deliveries observed. Rather than analysing retrospective data (written records of the delivery entered by a doctor/midwife); all cases were observed to eliminate recording bias. Although the clinician was unaware that the observer was collecting data on their practice, the presence of an observer may alter practice. 

Despite rates of OASIS at the Trust being less than the national average (1.2% in 2009); the 2016 audit was completed to optimise patient care. It highlighted that manual perineal protection and DRE- female post-delivery could be improved. Whilst 'PRactical Obstetric Multi-Professional Training' significantly improved the rates of good manual perineal protection; rates of DRE- female post-delivery remained suboptimal. Free texts notes made at the time of observation highlighted that midwives often deemed it “unnecessary” to complete a DRE- female, if examination of the vaginal wall revealed apparent minimal injury.

This re-audit highlights that the 2017 training programme was successful in improving manual perineal protection but requires updating to put a greater emphasis on the importance of a DRE- female. These findings have been disseminated using our local monthly quality improving meetings and monthly newsletters. Furthermore, a midwifery e-learning package could be launched on post-OASIS morbidity and preventative measures. A re-audit to assess effectiveness of these interventions should be completed in three years (2022).

Royal College of Obstetricians and Gynaecologists (2015) Third and Fourth Degree Perineal Tears, Management (green top guideline 29) London: RCOG Available at: https://www.rcog.org.uk/en/guidelines-research-services/guidelines/gtg29/
OASI Care Bundle Project Team. Implementation guide for maternity sites in the roll-out. Available at: https://www.rcog.org.uk/globalassets/documents/guidelines/research--audit/oasi-care-bundle/oasi-care-bundle-guide-final-_-050118.pdf