Anal fissure

Question 1

Define anal fissure.

Answer 1

Anal fissure is a split in the skin of the distal anal canal characterised by pain on defecation and rectal bleeding

Question 2

How common are anal fissures?

Answer 2

• It is a common condition in young to middle-aged adults and may occur in 1 in 350 people in the EU
• It is the second commonest gastro-intestinal complication of pregnancy after haemorrhoids.
• It is equally common in men and women, and often affects young adults aged 15 to 40

Question 3

What is the aetiology of anal fissure?

Answer 3

Passing of hard stools - hard stool tears the anal canal from the pectin (at the dentate line). Blood supply is reduced by the spasm of internal anal sphincter and so there is not enough blood supply to heal the split skin causing pain.*

Other theories: ischaemia in the anterior and posterior midline of the anal skin and a deficiency in the intrinsic NO synthase pathway(causing spasm).

*All treatments aim to reduce internal anal sphincter spasm to restore blood flow.

Question 4

Where do most anal fissures occur?

Answer 4

More than 90% occur in the posterior midline of the anal canal

Question 5

What problems do the sphincter spasms cause? (2)

Answer 5

Cause pain.
Impair wound healing.

Question 6

What is associated with an anal fissure?

Answer 6

Hypertonicity of the internal sphincter.

Question 7

What are the risk factors for anal fissure?

Answer 7

• Hard stool
• pregnancy
• opiate analgesia

Question 8

What are the symptoms of anal fissure?

Answer 8

• Pain on defecation - like passing shards of glass
• Tearing sensation on passing stool
• Fresh blood on stool or on paper
• Anal spasm - reported by 70%
• Wax and wane symptoms
• Mucus discharge
• Pruritus

Question 9

What are the signs of anal fissure?

Answer 9

• Fissure on retraction of the buttocks - liner split/tear shaped ulcer
• Sentinel pile/skin tag
• Spasm of the anus on parting buttocks

NB: DRE should not be done as this is too painful

Question 10

What investigations should be done for anal fissure?

Answer 10

Clinical diagnosis only - usually just from history. Alternatively parting buttocks and looking around anus but NOT DRE as this is too painful and there are sphincter spasms.

Other:

• Anal manometry - low resting pressure in some
• Anal ultrasound - may show defects in internal or external anal sphincter

Question 11

How do you manage anal fissure?

Answer 11

1. Conservative treatment - high fibre diet, adequate fluid intake, sitz baths, topical analgesia. Stool softeners can make defecation less painful.
2. Topical glyceryl trinitrate +/- analgesia - intra anal applied BD for 6 weeks. Avoid in pregnant/lactating women.
3. GTN may cause headache due to vasodilation… so alternatively use topical diltiazem 2%

Resistant fissures:

• botulinum toxin injection - seful in female patients about whom there is concern over the integrity of the anal sphincters following childbirth.
• surgical sphincterotomy - risk of faecal leakage and incontinence
• anal advancement flap

Question 12

What are the complications of anal fissure?

Answer 12

• Chronic anal fissure
• Incontinence after surgery and recurrence

If the fissure occurs off the midline, or there is a suspicious history, there many be an underlying pathology for the fissure.
These include:

• AIDS.
• Crohn’s.
• Carcinoma.

Question 13

What is the prognosis with anal fissure?

Answer 13

• 60% will achieve healing of fissure at 6-8 weeks
• 20% will heal after a course of topical diltiazem
• 30% will relapse and require a surgical option