Section: Colorectal Sub-section: Proctology Curriculum: Curriculum, page 18
Definition
Linear ulcer in the squamous epithelium of the anal canal distal to the dentate line.
Epidemiology
Male same as female Any age
Pathophysiology
Precipitated by local trauma
- Cycle of repetitive trauma, sphincter spasm and relative ischaemia
- Local trauma → anodermal tear below dentate line → pain
- Spasm of internal anal sphincter and there is reduced NO production
- Reduced local blood flow at watershed sites (anterior and posterior as blood supply comes in laterally)
- Inverse relationship between perfusion of anal canal and sphincter pressure
- Can lead to a chronic ulcer
Aetiology
- Common (posterior and anterior) straining , obstetric injury, trauma
- Constipation
- Diarrhoea
- Penetrative anal intercourse
- Vaginal delivery
- Atypical lateral fissures (painless, multiple)
- Inflammatory - Crohn’s disease, UC
- Granulomatous - TB, sarcoid
- Malignant - anal SCC, leukaemia
- Communicable - HIV, herpes, syphilis, chlamydia
Classification
- Acute vs chronic >6/52
- Superficial vs deep.
- Superficial anal fissures will show as a linear tear while deeper fissures may show the white transverse fibres of the internal anal sphincter. Deep fissures may also have fibrotic edges and are commonly associated with an External anal skin tag, often called a ‘sentinel pile’ and with a hypertrophic Anal papillae
- Location - posterior (80-90%), anterior (2-10%), other
Clinical
- Pain typically during defecation
- Bleeding
- Pruritus ani
- Correlating causative factors to enquire about on hx as above
- Sentinal tag and dilated anal papilla
Investigations
- Perianal examination
- Intolerance of proctoscopy
- Work up for rare causes
Treatment
Goals of Treatment
- Reduce sphincter spasm
- Control pain
- Treat underlying cause
Lifestyle
- Laxatives/bulking agents/loperamide
- Analgesia
Medical
- GTN paste - rectogesic
- Ointment applied TDS for 6/52 with gloves
- Nitrate - via NO mediated cGMP cascade SM relaxation
- SE - headaches, local irritation
- DIltiazem paste - 2%
- Paste applied TDS 6/52 with gloves
- Calcium channel blocker causing SM relaxation
- Local irritation
Surgical
- Botox injection
- 70% effective
- ACh blocker - inhibits NMJ signalling → sphincter relaxation
- Effect lasts for 3 months - should allow fissure to heal
- 50 units each side - IS groove/IAS
- Or 33 units to start and repeat at higher dose
- Side effects - faecal seepage, temporary
- Internal lateral sphincterotomy
- 90% effective
- Side effects - incontinence
- Fissurectomy and MAF
- Variable effectiveness
- Anocutaneous flap
- Fissurectomy
- Two parallel longitudinal incisions of the skin and preparing a rectangular skin flap which was raised and separated from the subcutaneous tissue
- Sutured with continuous monocryl
- Side effects - flap failure, recurrence, pain
- Useful for low pressure fissures https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8803790/#:~:text=Anocutaneous%20advancement%20flap%20is%20a%20very%20safe%20sphincter%2Dsparing%20surgical,fissures%20if%20medical%20treatment%20failed.