Anal fissures Flashcards
What are anal fissures?
Longitudinal or elliptical tears of the squamous lining of the distal anal canal.
When are anal fissures defined as acute and when are they defined as chronic?
- If present <6 weeks then acute
- > 6 weeks then chronic
What is the difference between primary and secondary anal fissures?
Primary: Due to local trauma with no underlying systemic disease (e.g., low fibre intake, chronic constipation, diarrhoea, anal sex).
Secondary: Due to underlying disease or pathology (e.g., previous anal surgery, IBD, infections, malignancy).
What are the risk factors for anal fissures?
- Hard stool - can tear skin in the distal anal canal
- Constipation - can tear skin in the distal anal canal
- Pregnancy (3rd trimester or after delivery)
- Opiate analgesia
- Inflammatory bowel disease
- STI (e.g., HIV, herpes, syphilis).
What are clinical features of anal fissures?
- Pain on defecation
- Tearing sensation on passing stool
- Painful, bright red, rectal bleeding
- Anal spasm
- 90% of anal fissures occur on posterior midline (visible on parting of the buttocks)
What should be considered if fissures are found in other locations?
Underlying causes e.g. Crohn’s disease.
What is the first line investigation for anal fissures?
Clinical diagnosis - no tests necessary at initial presentation.
What bedside investigations can be done if we suspect anal fissures?
- Abdominal exam
- DRE (Digital Rectal Examination) to look for fissure.
What stool test can be done if we suspect anal fissures?
- FIT test (detects blood)
- Faecal calprotectin (to check for IBD).
What imaging could be done for suspected anal fissures?
- Proctoscopy - proctoscope to see the rectum - for more superficial lesions e.g fissure
- May do Anal Manometry (muscle tone) or Anal Ultrasound (visualise the anal canal - can see deeper structural defects)
How do we manage acute anal fissures less than a week?
- Soften stool
- Bulk-forming laxatives are first line → if not tolerated than lactulose (laxative) should be tried
- Dietary advice → high fibre diet and high fluid intake
- Lubricants e.g. petroleum jelly may be tried before defecation
- Sitz bath - warm water bath that is used to immerse the anal area and promote healing and reduce pain
- topical anaesthetics
- analgesia
How do we manage chronic anal fissures?
- Techniques in previous toggle
- Topical glyceryl trinitrate (GTN) or diltiazem first-line for chronic anal fissure
What should be done if topical GTN is not effective after 8 weeks in a chronic anal fissure?
Secondary care referral for surgery (sphincterotomy - sphincter cut to relive tension and promote healing) or botulinum toxin.
What are some complications of anal fissures?
Complications → chronic anal fissure, incontinence after surgery (cannot control release), recurrence
Describe the prognosis at various stages of an anal fissure.
- 60% heal at 6-8 weeks
- Further 20% heal with topical diltiazem
- 30% may require surgical option.
