Anal fissure

Essentials

  • Conservative treatment should be preferred in newly emerged and mild cases.
  • A chronic fissure requires surgery.
  • Remember inflammatory bowel diseases and cancer in the differential diagnosis.

Aetiology

  • The aetiology of an anal fissure is not exactly known but it most obviously originates from a small injury to the mucosa of the rectal channel, which results in spastic contractions of the internal anal sphincter. Since the blood vessels to the mucosa run through the sphincter muscle, the mucosal circulation is impaired by the spasm. The most common location of the fissure is in the posterior midline, where the circulation of the rectal mucosa is the weakest even in the normal state.
  • Hard stools in association with constipation or frequent bowel movements in association with a diarrhoeal disease may act as predisposing factors.

Location

  • A fissure is usually located dorsally in the midline of the anal canal (> 80%). The second most common site is the anterior midline (> 10%).
  • Suspect Crohn's disease if a fissure is not located in the midline.

Symptoms

  • The main symptom is anal pain that intensifies during defecation.
  • Small amounts of bright blood may be seen in the toilet paper.

Treatment

  • Spontaneous recovery occurs in 60–80%.
  • If the symptoms have not been present for longer than a month, spontaneous recovery should be expected. Local anaesthetic gel or ointment before and after defecation may alleviate pain. Toilet hygiene should be good. Warm sitz baths (40°C) twice daily for 15–20 min may relax sphincter spasm and alleviate pain.
  • An extemporaneous preparation containing a calcium channel blocker: diltiazem 0.8 g mixed with emollient (oil in water emulsion) 40 g, or nifedipine 60 mg mixed with emollient 30 g; applied topically three times daily for a period of 8 weeks.
    • Unlike nitrate ointment, these preparations do not cause headache.
  • Nitrate ointment put daily into the anal passage has been shown to be significantly better than placebo and may help to avoid surgery in a number of patients [Evidence Level: B]. A ready-made preparation is available (Rectogesic®).
  • Obstipation is managed with bulk laxatives.

Chronic fissure

  • If a fissure persists for more than 2 months the condition should be classified chronic. The fibres of the internal sphincter muscle are visible at the bottom of the fissure. A "sentinel fold" is often seen in the anus, and there is a hypertrophic anal papilla at the dentate line in the anal canal.
  • Conservative treatment with nitrate ointment or calcium channel blocker cream should be tried as 50% heal with this therapy. Botulin toxin injections have also been successful.
  • In surgical therapy, internal sphincterectomy is performed under local or general anaesthesia. Manual anal sphincter dilatation is no longer recommended [Evidence Level: A]. Internal sphincterectomy in local anaesthesia can be performed in ambulatory care. The fissure itself does not need to be treated.
  • If the fissure recurs after sphincterotomy, a skin flap can be transplanted from outside the anus on the ulcer (anoplasty).
  • A disturbingly large sentinel fold and hypertrophic anal papilla can be excised.

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