A 30-year-old man presents with severe anal pain occurring during and for 20-30 minutes after defecation, with minor bright-red bleeding on the toilet paper. He is constipated. On gently parting the buttocks, a split is seen in the posterior midline of the lower anal canal. What is the diagnosis?

Answer: B. Anal fissure

Anal fissure

An anal fissure is a split in the skin of the lower anal canal. It causes severe pain during and after defecation (often 20-30 minutes), with minor, bright-red anal-canal-type bleeding, and is strongly associated with constipation.

Key features

• Pain causes spasm of the internal sphincter, which impedes healing (a vicious cycle).
• Most fissures are in the posterior midline (6 o'clock); anterior fissures are more common in postpartum women.
• A sentinel tag/pile and visible internal sphincter fibres in the base suggest chronicity (> 6 weeks arbitrary).
• Multiple fissures should prompt thoughts of Crohn's disease.

Diagnosis

• By inspection (gently parting the buttocks); proctoscopy/DRE is too painful and should be avoided in a conscious patient with an acute fissure.

Management

• Conservative first (warm sitz baths, bulk formers, stool softeners, fluids, local anaesthetic gel); then GTN/diltiazem/nifedipine (relax the sphincter); lateral internal sphincterotomy for chronic/intractable cases.