Article Text


Inflammatory bowel disease II
PTU-118 A diagnostic accuracy meta-analysis of endoanal ultrasound and MRI for perianal fistula assessment
  1. M R S Siddiqui1,
  2. H Ashrafian2,
  3. P Tozer1,
  4. N Daulatzai1,
  5. D Burling3,
  6. A Hart3,
  7. T Athanasiou2,
  8. R K Phillips1
  1. 1Colorectal Surgery, St Marks Hospital, London, UK
  2. 2Imperial College, London, UK
  3. 3St Marks Hospital, London, UK


Introduction Imaging modalities such as endoanal ultrasound or MRI can be useful preoperative adjuncts prior to the appropriate surgical intervention for perianal fistulas. We present a systematic review of published literature comparing endoanal ultrasound with MRI for the assessment of idiopathic and Crohn's perianal fistulas.

Methods A meta-analysis was performed to obtain pooled values for specificity and sensitivity. Electronic databases were searched from January 1970 to October 2010 for published studies.

Results Four studies were used in our analysis. There were 241 fistulas in the ultrasound group and 240 in the magnetic resonance group. The combined sensitivity and specificity of magnetic resonance for fistula detection were 0.87 (95% CI 0.63 to 0.96) and 0.69 (95% CI 0.51 to 0.82). There was a high degree of heterogeneity between studies reporting on MRI sensitivity (df=3, I2=93%). This compares to a sensitivity and specificity for endoanal ultrasound of 0.87 (95% CI 0.70 to 0.95) and 0.43 (95% CI 0.21 to 0.69) respectively. There was a high degree of heterogeneity between studies reporting on EAUS sensitivity (df=3, I2=92%).

Conclusion From the available literature, the summarised performance characteristics for MRI and EAUS demonstrate comparable sensitivities at detecting perianal fistulas, although the specificity for MRI was higher than that for EAUS. Both specificity values are however considered to be diagnostically poor. The high degree of data heterogeneity and the shortage of applicable studies precludes any firm conclusions being made for clinical practice. Future trials with improved study design (including prospective data collection and consideration of verification bias) may help to further clarify the role of MRI in the assessment and treatment response monitoring of perianal fistulas (particularly in patients with Crohn's disease).

Competing interests None declared.

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