Anal fistula or abscess? Different problems and next steps

A collection versus a tract

An abscess is a collection of pus that can cause pain and swelling. A fistula is an abnormal connection, usually between the anal canal and skin. A fistula may remain after an abscess, but anal pain alone establishes neither diagnosis.

Does no drainage exclude a fistula?

Drainage can be intermittent, so its absence alone does not exclude a fistula. Equally, pain during bowel movements should not automatically be labelled a fistula without supporting findings. Examination and the history determine what needs further assessment.

When does urgency change?

Severe or increasing pain, especially with fever or swelling, needs urgent assessment for an abscess. A deep collection may lack obvious external swelling. Recurrent drainage calls for assessment of the tract and continence before choosing definitive treatment.

Questions for your appointment

• Is there a collection that needs drainage now?
• What supports the diagnosis of a fistula?
• Would imaging clarify recurrent or deeper disease?

Further reading

• ASCRS — Abscess and fistula guideline (2022)

Related guides

• Anal abscess
• Anal fistula
• Anal fissure