High-yield map
Key points before the detail
- 01
Typical fissure pain continues after defecation because of sphincter spasm.
- 02
Posterior midline is typical; lateral or multiple fissures require investigation.
- 03
Soft stool is treatment, not generic lifestyle advice.
- 04
Topical GTN or diltiazem provides reversible chemical sphincter relaxation.
- 05
Sphincterotomy is effective but must be balanced against permanent continence risk.
1. Mechanism
Passage of hard stool or trauma can initiate a fissure. Reflex internal sphincter spasm raises resting pressure and reduces anodermal perfusion, perpetuating pain and poor healing. Not every patient is hypertonic, so sphincter division must be individualised.
2. Acute, chronic and atypical fissures
| Type | Features | Implication |
|---|---|---|
| Acute/early | Fresh linear tear without chronic secondary changes. | Stool regulation and analgesia heal many. |
| Chronic | Exposed internal sphincter, indurated edges, sentinel tag and/or hypertrophied papilla. | Add chemical relaxation; consider specialist procedure if refractory. |
| Atypical | Lateral, multiple, irregular, painless, mass-associated or non-healing. | Investigate Crohn disease, infection, trauma, dermatological disease or anal cancer. |
3. Presentation and examination
- Severe sharp pain during defecation followed by burning/spasm lasting minutes to hours.
- Small-volume bright-red bleeding.
- Gentle buttock separation often reveals the fissure.
- Do not force DRE or proctoscopy through severe pain when a typical fissure is clearly visible.
- Assess childbirth/obstetric injury, previous anal surgery and baseline continence.
4. First-line care
- Make stool consistently soft with fibre, adequate fluid and laxative support as required.
- Use non-opioid analgesia; opioids worsen constipation.
- Short-term local anaesthetic may help defecation but is not the healing treatment.
- Warm bathing may reduce spasm and improve comfort.
5. Chemical sphincter relaxation
| Treatment | Role | Caution |
|---|---|---|
| Topical GTN, commonly 0.4% | Nitric-oxide mediated internal-sphincter relaxation. | Headache, dizziness, hypotension and PDE-5 inhibitor interaction. |
| Topical diltiazem, commonly 2% | Calcium-channel blockade; often fewer headaches. | Usually off-label in the UK; local formulation varies. |
| Botulinum toxin | Temporary chemical denervation after failed topical therapy or when permanent division is undesirable. | Effect is temporary; repeat treatment may be needed. |
6. Surgery and continence risk
| Option | Role |
|---|---|
| Lateral internal sphincterotomy | Most effective durable treatment for selected chronic hypertonic fissure after failed conservative/medical care. |
| Advancement flap | Sphincter-preserving option for low-pressure fissure or high continence-risk patient. |
| Fissurectomy ± Botox/flap | Selected recurrent or fibrotic disease. |
Active recall
Close the notes and answer these
Try each question from memory before revealing the answer. These public prompts are a small preview of the integrated retrieval system inside SurgAtlas.
01Where is a typical anal fissure located?
Posterior midline; anterior midline can also occur, especially after childbirth.
02What location is a red flag?
Lateral or multiple fissures.
03What is the key first-line physiological treatment?
Make stool consistently soft and reduce trauma/straining.
04Name two topical chemical sphincter relaxants.
Glyceryl trinitrate and diltiazem.
05What is the main long-term risk of lateral internal sphincterotomy?
Permanent continence impairment.
Sources & editorial basis
References & editorial basis
- SurgAtlas production source. General Surgery — Anal Fissure. Public lesson curated from the corresponding production chapter.
- ACPGBI guideline. Management of anal fissure, Colorectal Disease 2023, as recorded in the SurgAtlas source register.
This lesson is derived from the corresponding SurgAtlas production teaching material. Where the source makes current management or guideline claims, the public lesson uses the cited contemporary guidance. It is written for education and examination preparation, not as patient-specific clinical advice.
Editorial details
Medical Doctor (MD) · MRCS Part A · Physician · Surgical Educator
SurgAtlas is an educational resource. For patient care, verify current national guidance, local antimicrobial and transfusion policies, specialty pathways and individual patient factors.
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