Accuracy and patient preference in evaluating perianal fistulas using hydrogen peroxide-enhanced three-dimensional endoanal ultrasonography and endoanal magnetic resonance imaging

Objectives: Surgery for perianal fistula is often complicated and therefore accurate preoperative assessment of perianal fistulas is necessary. The aim of this study was to determine agreement between hydrogen peroxide-enhanced three-dimensional endoanal ultrasonography (3D HPUS) and endoanal magnetic resonance imaging (MRI) in preoperative assessment of perianal fistulas and to assess patient preference with regard to these techniques.

Methods: Forty patients (aged 25–70 years) with symptoms of a perianal fistula and a visible external opening underwent preoperative 3D HPUS and endoanal MRI. The results were assessed separately by experienced observers. Fistulas were described according to the following characteristics: classification of the primary fistula tract according to Parks (intersphincteric, transsphincteric, extrasphincteric, suprasphincteric[RJF1]) or unclassified, location of the internal opening, presence of secondary tracts and fluid collections. Patients were asked to score the amount of discomfort experienced during both procedures and express their preference for either method.

Results: The median time interval between 3D HPUS and endoanal MRI was 14 days (range: 0–91). The methods agreed in 88% (35/40, kappa=0.45) for the primary fistula tract, in 90% (36/40, kappa=0.83) for the location of the internal opening, in 78% (31/40, kappa=0.62) for secondary tracts, and in 88% (35/40, kappa=0.63) for fluid collections. There was no significant difference between the amount of discomfort experienced during 3D HPUS and endoanal MRI or in patient preference for one procedure over the other.

Conclusions: 3D HPUS and endoanal MRI are equally effective for the evaluation of perianal fistulas. The methods do not differ with respect to patient discomfort and patients have no preference for either procedure.