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:
- Perianal
- Ischiorectal
- Intersphinteric
- Supralevator
- 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
Picture provided by Daniel Rosenthal, BA Medical
Centre, San Antonio, Texas, USA
Fistula-in-Ano
- 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
Investigation
- Clinical assessment
- MRI
- Ultrasound
Picture provided by Richard Brouwer, St Vincent's
Hospital, Melbourne, Australia
Treatment
- 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
Pruritus ani
Causes
- Idiopathic (50%)
- Anorectal (25%)
- Fissures
- Fistulae
- Papilloma
- Skin tags
- Haemorrhoids
- Dermatological (25%)
- Psoriasis
- Lichen Planus
- Candidiasis
- Threadworms
Treatment
- Keep perianal skin clean and dry
- Avoid rubbing and scratching
- Avoid perfumed medications, ointments and creams
- Keep bowel regular
Bibliography
Billingham R P, Isler J T, Kimmins M H
et al. The diagnosis and management of common anorectal
disorders. Curr Probl Surg 2004; 41: 586-645.
Hughes F, Mehta S. Anorectal sepsis.
Hosp Med 2002; 63: 166-169
McCourtney J S,
Finlay I G. Setons in
the surgical management of fistula-in-ano.
Br J Surg 1995; 82: 448 -
452.
Seow-Choen F,
Nicholls R J. Anal
Fistula.
Br J Surg 1992; 79: 197 - 205.
Thomas P.
Decision making in surgery; acute anorectal sepsis.
Br J Hosp Med 1993; 50: 204
- 205.
Zucatti G, Lotti T, Mastrolorenzo A
et al. Pruritus Ani. Dermatol Ther 2005; 18:
355-362. |