Diagnosis of Obstetric Anal Sphincter Injuries (OASIs)

Vaginal birth is now recognised as a major cause of anal incontinence in women and OASIs are a major aetiological factor. With the advent of anal ultrasound it had become apparent that doctors and midwives are not recognising all OASIs The Sultan classification ensures that injuries to the anal mucosa, internal and external sphincter are documented in order that appropriate repair is conducted. Failure to recognise an OASI is associated with adverse long-term outcomes. The first repair has the best chance of a good outcome and therefore obstetricians and midwives need to be adept at recognising these injuries. This chapter provides tips and tricks on how to recognise OASIs and avoid over and under-diagnosis.