January-March 2018

MRI in the Diagnosis and Pre-operative Classification of Perianal and Anal Fistulas

Bodagala Vijaya lakshmi devi1, Chegireddy Supraja2*, Yootla Mutheeswaraiah3, AY Lakshmi4, Settipalli Sarala5, Kadiyala Silpa6

1,2DMRD, DNB. Department of Radio Diagnosis, 3M.S Department of General Surgery, 4,6M.D, 5M.D, DNB, Department of Radio Diagnosis, SVIMS, Tirupathi, Andhra Pradesh.


BACKGROUND: This study was conducted to assess the value of MRI in diagnosis and pre-operative staging of perianal and anal fistulas. MATERIALS AND METHODS: Patients with perianal local pain and discharge were evaluated by pelvic MRI without any bowel preparation. Type of the fistula, location of the internal opening, presence or absence of secondary tracts, abscesses and a horseshoe component and supralevator extension were assessed. Cohen’s Kappa coefficient is used to analyze the agreement between MRI and surgical findings. Diagnostic standard of reference in all cases was the surgical findings. RESULT: Type of fistula was identified by using the St James’s University Hospital classification in 44 subjects with a mean of 38.9 years. The commonest type of ano-rectal fistula encountered in the study was Grade 1 seen in 37.5%. MRI showed sensitivity and specificity of 100% and 50% respectively in detecting internal opening, 100% and 93.33% respectively in detecting abscesses, 100% and 89.47% respectively in depicting secondary tracks, 85.71% and 100% respectively in detection of simple non branching tracks. MRI was 100% sensitive and specific in detecting horseshoe abscess and supralevator extensions. The concordance with surgery was 89.1%. Our results show that MRI findings were in substantial agreement (Cohen’s Kappa coefficient of 0.67) with surgical findings. CONCLUSION: MRI is a valuable tool in pre-operative evaluation of the perianal and anal fistulas. It provides high resolution images of the anatomy of the anorectal region with delicate depiction of the fistulous tracts with their associated secondary ramifications and abscesses.

Keywords: Perianal and anal fistulas, Magnetic Resonance Imaging, St.James University Hospital Classification

[Full Text Article]  
Twitter Links