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Endoanal ultrasound versus Magnetic resonance Imaging for perianal sepsis

Three Part Question

[For Recurrent Perianal sepsis] [is magentic resonance imaging better than endoanal ultrasound] for [evaluating fistulous tracks]

Clinical Scenario

A 20 year old female presents to casualty with complaints of recurrent pain and swelling in the perianal region. She has had similiar symptoms in the past and a perianal abscess was drained in the past but never really healed. On examination she has a small abscess with a fistulous track palpable. A diagnosis of recurrent perianal abscess is with an underlying fistula in ano. What is the evidence for the best available investigation to map the fistulous tracks.

Search Strategy

Medline 1966-12/01 using the OVID interface
({perianal AND magnestic resonance} OR {perianal AND endosonography}).

Search Outcome

8 articles. Only One non randomized prospective study comparing MRI and Endoanal sonography for evaluating perianal sepsis. Several reports about the role of MRI in evaluating perianal sepsis. A couple of reports quoting early experiences with perianal sepsis.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Maier et al,
Patients presenting with perianal fistulae and sepsis investigated either with anal endosongraphy or magnetic resonance imaging. Findings compared at surgeryProspective, non randomizedDiagnostic yeild of MRI and Anal Endosonography in the assessment of perianal abscesses and fistualaeMRI appears to be more specific and sensitive in the assessment of fistulous tracks in perianal sepsis1.Non randomized 2.Level of expertise of person performing anal endosongraphy not mentioned, this could have biased the results in favour of MRI


There are no randomized trials comparing MRI and anal endosonography.

Clinical Bottom Line

The current evidence supports MRI as the most accurate investigation for evaluating fistulous tracks in perianal sepsis.


  1. Maier AG, Funovics MA and Kreuzer SH et al Evaluation of perianal sepsis: comparison of anal endosonography and magnetic resonance imaging Journal of Magnetic Resonance Imaging 2001 Sep;14(3):254-260.