Anal sphincter and pelvic floor damage

Damage to one or both anal sphincters (internal and/or external) is the most common cause of faecal incontinence in younger people, particularly women after childbirth.

Sultan et al (1993)[1], using endoanal ultrasound, found evidence of new anal sphincter damage in 35% of women after a first delivery. Childbirth trauma may not present as a problem until later in life, particularly around the menopause.

Risk factors for anal sphincter damage following childbirth (known as OASIS – Obstetric Anal Sphincter InjurieS) :

  • Vaginal delivery using instruments eg forceps
  • Episiotomy – especially midline
  • 3rd or 4th degree tear
  • Long labour with prolonged pushing
  • First delivery
  • Birth weigh over 4kg
  • Maternal age over 30


Sultan AH, Kamm MA, Hudson CN, Thomas J, Bartrum CI. Anal sphincter disruption during vaginal delivery. New England Journal of Medicine. 1993;329;1905-1911. [Cited 31 July 2018] Accessed from:

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