Risk factors for and management of obstetric anal sphincter injury

Obstetric anal sphincter injury is the leading cause of faecal incontinence in women. Concerns have been expressed that some sphincter injuries are missed at the time of vaginal childbirth. There has also been a steady increase in the number of medico-legal cases associated with obstetric sphincter injury. Accurate diagnosis of third and fourth degree tears at the time of childbirth followed by primary repair by experienced personnel, in the correct setting, and using the correct technique has been shown to improve outcome and reduce faecal incontinence rates. This article provides a comprehensive review of the risk factors for obstetric anal sphincter injury, together with the diagnosis, management and follow up of these women, based on the best available evidence.