MAGNETIC-RESONANCE-IMAGING IN THE MANAGEMENT OF FISTULA IN ANO

Fistula-in-ano is a common condition in which accurate diagnosis of th e fistula track is essential as inadequate assessment and surgical tre atment may lead to multiple unnecessary operations and may also render the patient incontinent. Several studies have suggested that Magnetic Resonance Imaging (MRI) can accurately identify the fistula track in relation to the sphincter complex. The aim of this study was to invest igate the value of the routine use of completely non-invasive pre-oper ative MRI in patients with suspected fistula-in-ano. Each scan was rep orted by a consultant radiologist on two occasions to determine whethe r the radiologist's opinion had changed and/or become more accurate wi th further experience. Surgical assessment of the fistula was performe d under general anaesthesia by one surgeon without knowledge of the re sult of the MRI scan. The results of the surgical assessment and the M RI scan were compared and the surgical procedure completed. Thirty thr ee patients with a clinical diagnosis of fistula-in-ano were treated a nd 27 subsequently confirmed to have a fistula. MRI detected 42% of tr acks, identified correctly on initial assessment which increased to 50 % at the end of the study, 63% and 74% of internal openings, 33% and 4 6% of external openings and 50% and 33% of abscesses. These data sugge st that there is a learning curve for radiologists undertaking MRI sca nning for fistula in ano, this is probably because the pathology of fi stula in ano and anatomy of the anal sphincter complex are relatively new to radiologists. Routine MRI scanning of patients with fistula-in- ano is not necessary but there may be a role for MRI in assessing comp lex or difficult fistulae.