Anal Fissure
What is anal fissure?
Anal fissure is a tear in the thin tissue that lines the anus or the anal canal (the opening through which stool passes out of the body).
Causes of anal fissure
Anal fissure is commonly caused by trauma to the anal canal, which can be secondary to:
Chronic constipation
Straining during defecation (large or hard stool may worsen the situation)
Prolonged diarrhoea
Foreign body insertion
Other non-traumatic causes include:
High anal pressure / anal spasms
Underlying inflammatory bowel disease
Anal cancer (SCC, lymphoma)
Sexually transmitted infections
Symptoms of anal fissure
Main symptom of an anal fissure is pain during and after defecation. It may be associated with small amount of bleeding or foul smelling discharge.
How is anal fissure treated?
A consultation with your GP and subsequent referral to a colorectal surgeon will ensure that your symptoms are appropriately assessed and treated. If the diagnosis is unclear on history and bedside examination, patient should undergo an examination under anaesthetic in theatre to confirm the diagnosis.
The surgeon would exclude secondary causes of anal fissure if its located in an atypical location or if the fissure fails to respond appropriately to treatment. For patient with persistent bleeding, a colonoscopy should be performed to exclude a more proximal cause.
Conservative measures should be initiated and likely need to be continued to ensure good bowel movement. Most anal fissures are managed with non-operative therapy, with surgery reserved for those refractory to therapy.
Diet, and ensure good bowel habit
Increase fibre + fluid intake
Aim for stool consistency to reach “toothpaste consistency”
Avoid straining during defecation
Maintain good perianal hygiene and have warm SITZ baths (up to 3x per day)
Medications
Bulking agents e.g. Metamucil (1-3x / day), Psyllium husk
Stool softeners e.g. Movicol or Lactulose
Simple oral (e.g. Paracetamol) or topical analgesia (e.g. 2% lignocaine gel)
Topical vasodilators, trial twice a day for 1 month
Calcium channel blockers (e.g. 0.2% Nifedipine or 2% Diltiazem) or
Nitroglycerin (GTN cream)
Surgical management options:
Botox injection - Botox (50-100 units) is injected in 2-3 sites in the anal canal to reduce the spasm of the anal sphincter. This aims to improve blood flow to the fissure and promote healing.
Fissurectomy - Involves excision of the chronic fibrotic tissue of the fissure base and edges. It is usually performed in conjunction with another procedure, providing reasonable healing with low recurrence rate.
Lateral internal sphincterotomy - Internal sphincter is divided up to the apex (top part) of the anal fissure. This is done under general anaesthetic, as a day procedure. The risk of incontinence in the general population is 2%.
Anal advancement flap - Is used for treatment of chronic anal fissure. A flap of anal margin distal to the fissure, with preservation of the internal sphincter, is raised to facilitate closure of the internal sphincter. The risk of incontinence is very low.