anal stenosis

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(anal stricture)

The narrowing of the anal canal, located just before the anal sphincter.
It can be a disabling condition, affecting quality of life in many ways.
Patients sometimes resort to excessive use of laxatives to find temporary relief.

The anal sphincter maintains a seal that can be opened to discharge body waste.
It is strong enough to restrict the passage of any fecal material but sensitive enough to differentiate between solid, liquid, and gas.

(Types of anal sphincter)
• internal anal sphincter: A thin, white involuntary smooth muscle around the anal canal.
• external anal sphincter: A thick, red voluntary skeletal muscle around the internal anal sphincter. It responds to volitional commands to contract and maintain continence when feces are propelled through a relaxed internal anal sphincter into the rectum.

(Symptoms)
• constipation
• painful bowel movements
• stools narrow and broken apart like pellets: Due to being difficult to be expelled.
• hematochezia: Passage of fresh blood through the anus, usually in or with stools.

(Causes)
It can be caused by a intrinsic or extrinsic pathologic process of the anorectum (scarring of the anoderm, the epithelial lining of the anal canal located inferiorly to the dentate line and extends for about 1.5 cm. Long-term inflammation in the rectum sometimes causes scarring.
• complication of anorectal surgery: Most commonly, after hemorrhoidectomy.
• trauma
• radiation therapy
• chronic laxative abuse: Can cause constipation, laxative dependency, fluid and electrolyte imbalance (esp. hypokalemia), spastic colitis, etc.
• perianal Crohn disease: An inflammatory bowel disease at or near the anus, including tags, fissures, fistulae, abscesses, or stenosis.
• ischemic proctitis
• venereal disease
• tubercolosis
• amebiasis: A violent inflammatory secondary bacterial infection caused by the amoeba entamoeba histolytica, that may cause ameboma (proliferative fibrotic thickening, response of the colonic tissue produced by the invading amoebae and the synergistic bacteria) formation, colonic narrowing and being confused with carcinoma.

(Treatment)
• high fiber diet
• bulk laxatives
• gentle digital dilatation
• lateral internal sphincterotomy
• operative procedures: E.g. Y-V anoplasty, S-anoplasty, island flap anoplasty, C-plasty.