Comparison of Endoanal Ultrasound with Clinical Diagnosis in Anal Fistula Assessment.

BACKGROUND

Anal fistula anatomy and its relationship with anal sphincters are important factors influencing the results of surgical management. Pre-operative definitions of fistulous track(s) and the internal opening play a primary role in minimizing damage to the sphincters and recurrence of the fistula.

OBJECTIVE

To evaluate the relative accuracy of digital examination and endoanal ultrasound for pre-operative assessment of anal fistula by comparing operative findings.

MATERIAL AND METHOD: A retrospective review was conducted of all patients with anal fistula admitted to the surgical unit between May 2008 and May 2012. Physical examination and hydrogen peroxide-enhanced endoanal ultrasound (utilising a 10 MHz endoprobe, HITACHI: EUB-7500), were performed in 142 consecutive patients. Results were matched with surgical features to establish their accuracy in preoperative anal fistula assessment.

RESULTS

A total of 142 patients (107 men, 35 women), 28 of whom had had previous surgery, were included in the study. Their mean age was 40 (range 18-71) years and their mean BMI was 26.37 (range 17.30-36.11) kg/m². The majority of the fistulas were transphincteric (90.4%) and the rest were intersphincteric (9.6%). The accuracy rates of clinical examination and endoanal ultrasound were 55.63 and 95.07 percent (p < 0.01), respectively.

CONCLUSION

Endoanal ultrasound is superior to digital examination for pre-operative classification of anal fistula