Anorectal Pain

Differential Diagnosis

Common Diagnoses

Occasional Diagnoses

Rare Diagnoses

  • Anal Tuberculosis
  • Cauda Equina Syndrome
  • Endometriosis
  • Trauma
  • Presacral Tumours

Ready Reckoner

Key distinguishing features of the most common diagnoses

Anal FissureHaematomaAbscessPFMalignancy
Began While DefecatingYes No NoPossible No
Visible Anal Swelling NoYesPossible NoPossible
Pain IntermittentPossible No NoYes No
Rectal BleedingYesPossiblePossible NoYes
PR Exam ExcruciatingYesYesYesPossiblePossible

Possible Investigations


Possible:FBC, ESR/CRP, proctoscopy, faecal calprotectin

Small Print:Urinalysis, ultrasound, hospital-based lower GI investigations

  • FBC/ESR/CRP: WCC may be raised in abscess and Crohn’s disease. ESR/CRP raised in these and carcinoma.
  • Proctoscopy valuable if pain allows (specialist might also take biopsy).
  • Faecal calprotectin: May help in diagnosing Crohn’s disease.
  • Urinalysis: Pus cells and blood may be present in prostatitis or invasive bladder tumour
  • Ultrasound of pelvis if pelvic examination reveals a mass. In obscure cases, hospital-based lower GI investigations may be needed.

Top Tips

  • If the patient uses dramatic language (e.g. red-hot poker) to describe fleeting pain, is otherwise well and there are no obvious abnormalities on examination, the diagnosis is likely to be proctalgia fugax.
  • Examine the patient – the cause is usually a thrombosed pile/perianal haematoma, anal fissure or an abscess, and these can usually be diagnosed by simple inspection
  • Provide symptomatic relief but remember to deal with any underlying causes – especially constipation.
  • Don’t forget to ask about thirst and urinary frequency – recurrent abscesses may be the first presentation of diabetes.

Red Flags

  • Preceding weight loss and/or change in bowel habit should prompt a full urgent assessment with carcinoma and inflammatory bowel disease in mind.
  • Some perianal abscesses do not result in external swelling. If PR exam is prohibitively painful, consider this possibility – especially if the patient is febrile
  • In florid or recurrent perianal problems, think of Crohn’s disease as a possible cause.
  • Remember rarer causes in intractable, constant pain in a patient with no obvious signs on PR.

Published: 1st August 2022 Updated: 10th April 2024

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