Anal Fissure

It is an ulcer in the longitudinal axis of the lower anal canal.

Location

• Midline posteriorly- most common (more common in males)
• Midline anteriorly- next most common (more common in females)

Causes

• Due to the curvature of the sacrum and rectum, hard fecal matter while passing down causes a tear in the anal valve leading to posterior anal fissure.
• Anterior anal fissure is common in females due to lack of support to the pelvic floor.
• Haemorrhoidectomy
• IBD- esp. chron’s disease
• STD

Pathology

• It can be acute and chronic. Fissure ends above at the dentate line.
• Acute anal fissure
• It is a deep tear in the lower anal skin with  spasm of anal sphincter with little inflammatory induration or edemaof its edges.
• Chronic anal fissure
• It has got inflamed, indurated margin with scar tissue.
• Ulcer at its inferior margin is having a skin tag, which is edematous, acts like a guard-’ Sentinel Pile’
• It can cause repeated infection-fibrosis-abscess foramtion-fistula formation.

Clinical features

• Common in middle aged women, not in elderly.
• Pain is severe in nature in acute type, whereas less severe in chronic.
• Constipation, bleeding and discharge.
• O/E
• In standing cases there may be sentinel skin tag. Sentinel skin tag + typical Hx + tightly closed, puckered anus= pathognomonic. 
• In chronic fissure, ulcer is felt with button like depression, induration and often sentinel pile.
• The lower end of the fissure can be seen by gently parting the margins of anus.
• Digital examination and proctoscopy is not possible in acute fissure in ano. 

Anal fissure

Sentinel pile

Differential Dx

• Carcinoma of anus
• Inflammatory bowel disease
• Venereal diseases
• Anal chancre
• Tuberculous ulcer
• Proctalgia fugax

Treatment

Conservative t/t

• NO- neurotransmitter that induces relaxation of the internal spchicter.
• Glyceryl trinitrate- being nitric acid donor, when applied as an ointment causes relaxation of the sphincter and also improves blood flow- both aids healing. 
• Use of laxatives and xylocaine surface anaesthetic.

Surgical

Gentle dilatation of the sphincter under GA:

• Can be used in young men with high pressure sphincter.
• CI in pts. with weak sphincter.
• If this method is ineffective or if the fissure is chronic with fibrosis, a skin tag or a mucus polyp, then surgery is done under GA(best) or LA.

Lateral anal sphincterotomy:

• Here internal sphincter is divided away from the fissure either in right or left lateral positions.
• Can be done in OPD basis under L/A.
• Healing completes in 3 wks.
• Good result for acute than chronic cases.
• Small risk of incontinence.

Closed and open

Anal advancement flap:

• Here excision of the edges of the fissure and mobilization of a square, full-thickness anal skin flap which is slided forward over the fissure and sutured in place.
• Only little risk of damage to the underlying internal sphincter and incontinence is unlikely.