Anal Fissure

When I sat in on Colorectal Clinic, a woman came in complaining of severe burning pain on defecation, some bright PR bleeding and previous constipation 2 months prior. She was on Macrogol (laxative). She screamed when the proctoscope was introduced.


Anal Fissure

Definition: painful tear (elongated ulcer in the long axis) in the squamous lining of the lower anal canal

Aetiology/ risk factors:

-most are due to hard faeces and constipation; straining and hard stools tears the posterior anal lining

-90% are posterior, anterior fissures follow parturition when a damaged pelvic floor leaves the anterior anal tissues with less support

-spasm of the underlying sphincter muscle may pull on the tear and also constrict the inferior rectal artery, causing ischaemia, making healing difficult

Rare causes: syphilis, herpes, trauma, Crohn’s, anal cancer, psoriasis (= multiple +/- lateral fissures)

Epidemiology:

-most common under the age of 40

-incidence ∼1:350

-more common in males

Symptoms:

-severe burning pain on defecation

-pain may persist for hours

-PR bleeding- usually bright red, small in volume, on paper

-may be pruritus ani (itching)

Signs:

-if chronic, there is often a ‘sentinel pile’ or mucosal tag at the external aspect

-in chronic fissures, it may be possible to feel a firm indurated ridge

Image result for anal fissure

-gentle traction on the anal skin can reveal the distal part of the fissure

-DRE (digital rectal examination) may not be possible due to pain

-lymphadenopathy in the groin- suggests a complicating factor (e.g. immunosuppression/ HIV)

Investigations:

Diagnosis is made on history and examination.

Investigations are to exclude other conditions such as inflammatory bowel disease and rectal cancer e.g. sigmoidoscopy/ endoscopy

If there is no response to treatment, examination under anaesthesia may be necessary to exclude other pathology.

Management:

5% LIDOCAINE ointment + GTN ointment (0.2-0.4%)

or

topical DILTIAZEM (2%) = these reduce spasm of sphincter and increase local blood flow to encourage wound healing

or 2nd line – botulinum toxin injection = paralyse part of internal sphincter

-increase dietary fibre and fluids

-consider stool softener

-hygiene advice

-surgery is an option if conservative measures fail e.g. lateral partial internal sphincterotomy (the internal anal sphincter is cut, which lowers its resting pressure, which improves blood supply to the fissure and allows faster healing.) Anal advancement flaps may be used for chronic fissures (taking healthy tissue from another part of your body and using it to repair the fissure).

Complications:

-chronic fissure, chronic pain

-surgery = faecal incontinence, bleeding recurrence

Prognosis:

Recurrence is common, up to 50% of patients treated with topical nitrates and in less than 10% with lateral sphincterectomy.

References: Cheese & Onion, Rapid Surgery
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