ANOSOFT · Clinician Resource
GP Action Plan:
Anal Fissure
Diagnosis & first-line management in primary care — no specialist referral
A structured pathway for GPs: history, red flags, examination, differentials, investigations, and stepwise management.
This is a general clinical reference, not a substitute for individual clinical judgement or current NICE/CKS guidance. Confirm doses and contraindications against the BNF before prescribing.
Step 1
History
Cardinal symptom
Sharp, tearing pain during and for minutes–hours after defecation (distinguishes from painless haemorrhoids).
Bleeding
Bright red, on toilet paper or coating stool surface — not mixed in.
Bowel pattern
Constipation, hard stools, straining; obstetric/postpartum; chronic diarrhoea (IBD suspicion).
Duration
Acute (< 6–8 weeks) vs chronic (> 6–8 weeks); previous episodes; treatments already tried.
Risk context
IBD/Crohn's, HIV/immunosuppression, anal intercourse, STI exposure, family history of bowel cancer.
Step 2
Red Flags — Do NOT manage as simple fissure; refer
01
Atypical / lateral position (classic is posterior or anterior midline)
02
Multiple fissures or recurrent fissures
03
Non-healing after 6–8 weeks of optimal first-line therapy
04
Underlying IBD/Crohn's, HIV/immunosuppression, or STI risk
05
Suspicion of malignancy (indurated ulcer, mass, inguinal lymphadenopathy)
06
Severe pain preventing examination → examination under anaesthesia
07
Systemic features: weight loss, fever, night sweats; rectal bleeding with change in bowel habit (NICE 2-week-wait)
Step 3
Examination (primary care, no anaesthesia)
Inspection (gently part buttocks)
Most fissures visible as a linear ulcer/split in posterior or anterior midline. Look for the chronic fissure triad: fissure + sentinel skin tag + hypertrophied anal papilla.
Digital rectal examination (DRE)
Attempt only if tolerable; often too painful acutely — do NOT force it. If possible, assess sphincter tone, masses, tenderness, prostate.
Proctoscopy / anoscopy
Only if tolerated; frequently deferred acutely.
Abdominal exam & inguinal nodes
Masses, tenderness; inguinal nodes if STI/malignancy suspected.
Step 4
Differential Diagnosis to actively exclude
Haemorrhoids
Anal abscess / fistula
Crohn's disease
STI ulcers (syphilis, HSV, gonorrhoea, LGV)
HIV-related ulcer
Perianal TB
Step 5
Investigations (only if atypical, chronic, or red flags)
None (clinical diagnosis)
Classic acute fissure needs no tests.
FBC
Anaemia screen if bleeding/atypical.
CRP / ESR
Inflammation / IBD workup.
Faecal calprotectin
IBD screen in non-healing/atypical cases.
STI swabs + HIV test
If STI risk or atypical ulcer.
FIT test
If any bowel-cancer red flag present.
Step 6
First-Line Management (no referral needed)
Step 7
Review & Safety-Net
Review at 6–8 weeks
If healed → continue maintenance (fibre, fluids). If not healed or recurrent → refer to colorectal/surgical for specialist assessment (botulinum toxin, lateral internal sphincterotomy).
Safety-net advice
Return sooner if bleeding worsens, new mass appears, systemic symptoms develop, or pain becomes severe/uncontrolled.
Step 8
When to Refer (summary)
Atypical location
Multiple or recurrent fissures
Non-healing at 6–8 weeks
IBD / HIV / STI context
Malignancy suspicion
Pain preventing examination
Red-flag bowel symptoms
For Healthcare Professionals Only
This section of the Anosoft website is intended exclusively for UK healthcare professionals and authorised prescribers.
The information provided is for professional reference and is not intended for patients or the general public. It should be considered alongside the relevant prescribing information and does not replace independent clinical judgement.
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