Anal Fissure

Question 1

Definition of anal fissure

Answer 1

• a split in the skin of the distal canal characterised by pain on defecation and rectal bleeding
• common in 15-40 years
• 1 in 350 people
• 2nd most common GI complication of pregnancy after haemorrhoids
• severe pain like glass

Question 2

Risk factors for anal fissures

Answer 2

• hard stools
• pregnancy (3rd trimester or after delivery)
• opiate analgesia

Question 3

Aetiology of anal fissures

Answer 3

• passage of hard stools
• often occurs spontaneously
• opiate analgesia associated with constipation and subsequently increases risk
• hard stool tears anal skin from the pectin (at the dentate line) but alternatively there could be ischaemia in the anterior posterior midline of the anal skin and a deficiency in intrinsic nitric oxide synthase pathway

Question 4

Pathophysiology of anal fissures

Answer 4

• may be ischaemic ulcer
• poor blood circulation in the posterior midline of the anal canal, where more than 90% of the fissures occur- this blood supply further reduced by spasms of the internal anal sphincter
• when hard stool tears the skin, not enough blood supply to heal

Question 5

Classification of anal fissures

Answer 5

timeframe

Acute:
-spontaneously heal after 1 or 2 weeks before medicatin

Chronic:

• > 6 weeks
• other morphological features such as indurate edges, skin tag, visible internal anal sphincter fibres at its base

Question 6

Symptoms of anal fissure

Answer 6

• severe sharp glass like pain
• some blood- bright
• pain after defecation lasts up to an hour or longer

Question 7

Physical examination for anal fissures

Answer 7

• gently part the buttocks, marked spasm of the anus seen
• may be skin tag if symptoms for long time
• parting buttocks more, lower end of the fissure can often be seen as a linear split in the skin/tear-shaped ulcer
• acute = resembles paper cut
• chronic = wider, indurated edges, visible fibres
• lateral fibres seen = alternative diagnosis; Chron’s, TB, sarcoidosis, syphilis, HIV, anal cancer, ulceration secondary to treatment with nicorandil

-further examinations under anaesthesia

• Anal manometry considered in women who has obstetric injury (third-degree tear), as low resting pressure can contraindicate the need for sphincterotomy
• US useful adjunct to manometry to identify anatomical cause for low anal sphinctal pressure= defects in internal/external anal sphincter

Question 8

Diagnosis of anal fissures

Answer 8

• risk factors
• pain on defecation
• tearing sensation
• fresh blood on stool or paper
• anal spasm
• 60% intermittent symptoms
• 20% sentile pile (skin tag)
• 40% fissure visible on buttock retraction

Question 9

Differentials other than anal fissure

Answer 9

• Crohn’s disease - abnormal peri-anal skin, lateral fistulae, abdominal pain, diarrhoea, systemic symptoms
• Sarcoidosis- lateral fissure, cough, dyspnea, facial palsy…
• TB- lateral fissure, TB of abdomen also present- enlarged lymph nodes, swelling, systemic symptoms
• HIV infection- unprotected anal, needle sharing
• Lymphoma- lymphadenopathy elsewhere, night sweats, systemic symptoms
• Syphilis- unhealing fissure, sexual contact with infected person, serum tests +
• Anal carcinoma- Hx of human papillomavirus infection, atypical site and fissure shape, biopsy= squamous cell carcinoma

Question 10

Management of anal fissures

Answer 10

Conservative treatment

• high fibre diet, more fluid, sitz baths, stool softeners, analgesics
• later, topical nitrates or Ca channel blockers
• diltiazem
• Topical glyceryl trinitrate
• Topical diltiazem

Resistant fissures:

• botulinum toxin
• surgical sphincterotomy
• anal manometry
• anal advancement flap- higher failure rate than sphincterotomy but lower risk of incontinence, surgical alternative in selected high-risk cases

-endocanal US

Question 11

Emerging treatments for anal fissures

Answer 11

• Phoshodiesterase-5 inhibitors- relax the internal sphincter, sildenafil
• Potassium channel openers- minoxidil to relax the internal sphincter
• Transcutaneous electrical posterior tibial nerve stimulation

Question 12

Complications of anal fissures

Answer 12

• Chronic anal fissure-
• Incontinence after surgery- 30%
• Recurrence

Question 13

Prognosis of anal fissures

Answer 13

• 60% heal fissure in 6-8weeks
• further 20% heal after topical diltizaem
• relapses- 30% require surgical option