Introduction and hypothesis: Perineal trauma affects approximately 350,000 women per annum in the United Kingdom (UK) and is associated with considerable morbidity. Symptoms are most severe following obstetric anal sphincter injuries (OASIS) compared with other grades of perineal trauma. The Royal College of Obstetricians and Gynaecologists (RCOG) guidelines indicate that the rate of OASIS is 1 % of vaginal deliveries. In 2011, the RCOG implemented the "Maternity Dashboard" so that units could benchmark their performance against national standards of which OASIS is a component. Our primary objective was to establish the national rate of OASIS and audit variations in incidence and management of obstetric perineal trauma.
Methods: We carried out a questionnaire-based survey auditing national practice. Every UK maternity unit was contacted regarding perineal outcomes after all deliveries between January 2009 and January 2010.
Results: 215 of the 265 units in the UK responded (81 %). 692,259 of the 790,197 deliveries in the UK for the same period were sampled (88 %). 75 % delivered vaginally. The median national OASIS rate was 2.85 % (0-8 %). 20.2 % of women delivering vaginally had episiotomies; none were midline. 12.4 % of second-degree tears were not repaired in low-risk units compared with 5.9 % in high-risk units. 57.1 % of units used the perineal trauma classification of the RCOG.
Conclusions: This study provides comprehensive data regarding the incidence and management of perineal trauma across the UK. Clinicians and policy-makers, both local and at the RCOG, can devise up-to-date realistic guidelines on the anticipated rate of OASIS and help to assess the compliancy of units with guidelines on the appropriate management of perineal trauma.