Anatomy of anal canal
- Internal sphincter = smooth muscle
- External sphincter = striated muscle
- Mucosa of upper third of anal canal – no somatic sensation
- Mucosa of lower tow thirds of anal canal- somatic innervation from inferior rectal nerves
- Anal gland occur in intersphinteric plane & open at level of dentate line
Perianal & ischiorectal abscess
- Probably arise from intersphinteric sepsis (Cryptoglandular Hypothesis)
- Abscesses classified as:
- Initial surgery should simply be incision and drainage
- Avoid looking for fistula at initial surgery
- Rectal EUA at approximately five days
- Especially if gut related organisms on culture
- 80% recurrent abscesses associated with a fistula
- Goodsall's Rule = An external opening situated behind the transverse anal line will open into the anal
canal in the midline posteriorly. An anterior opening is usually associated with a radial tract
- Fistulae may be classified as:
- Intersphinteric (70%)
- Transphinteric (25%)
- Suprasphinteric (5%)
- Extrasphinteric (<1%)
- Extrasphinteric fistulae are usually not associated with intersphinteric sepsis
- Consider inflammatory bowel disease or neoplasia
- Clinical assessment
Picture provided by Richard Brouwer, St Vincent's Hospital, Melbourne, Australia
- Puborectalis is the key to future continence
- Low fistulas - Lay open with either fistulotomy or fistulectomy
- High fistulas - Require two stage surgery
- Setons - loose or tight
- Anorectal advancement flap may be considered
Picture provided by Kahlid Hameed, Aga Khan University Hospital, Karachi, Pakistan
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