Anal Swelling

Differential Diagnosis

Common Diagnoses

  • Prolapsed Pile
  • Perianal Haematoma
  • Skin Tags
  • Perianal Abscess
  • Rectal Prolapse

Occasional Diagnoses

Rare Diagnoses

  • Hidradenitis
  • Anal Fistula
  • Carcinoma

Ready Reckoner

Key distinguishing features of the most common diagnoses

Prolapsed PilePerianal HaematomaSkin TagsPerianal AbscessRectal Prolapse
Painful PossibleYes NoYes No
Intermittent Possible No No No Possible
Constipated Possible Possible No Possible Possible
Long History Possible NoYes No Possible
Rectal Bleeding Possible Possible No Possible No

Possible Investigations

  • In most cases, investigation will be unnecessary. The only exceptions are warts (in which case referral to the local GUM clinic may be required to screen for sexually transmitted disease) and possible carcinoma (in which case biopsy will be performed in secondary care). Also, any suspicion of Crohn’s disease causing perianal disease would be investigated in hospital in the usual way.

Top Tips

  • This is one of those situations in which a brief history can be taken while the patient is undressing, or during the examination. Atypically for primary care, it’s the examination, rather than the history, which usually provides the definitive diagnosis.
  • If a discharge, as well as a lump, is mentioned by the patient, then abscesses, warts, prolapses and fistulae top the list of differentials.
  • The patient with an anal swelling who has obvious difficulty walking into the consulting room has either an abscess, a large perianal haematoma or strangulated prolapsed piles.

Red Flags

  • Recurrent or multiple fistulae suggest Crohn’s disease.
  • If a prolapsed pile is very swollen and painful, it is probably strangulated, and so requires urgent surgical attention.
  • A persistent, ulcerating anal swelling, especially in the middle-aged or elderly, requires urgent biopsy to exclude carcinoma.
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