Magnetic resonance imaging versus clinical examination in the diagnosis of fistula-in-ano: A comparison at a high-volume fistula center

Abstract

Background: Proper treatment of fistula-in-ano is based on the accurate diagnosis. Digital rectal examination helps delineating the changes associated with the fistula, as well as helps in knowing the course of the same. Magnetic resonance imaging (MRI) is a well-tolerated, painless, and accurate diagnostic modality that helps in predicting the tract-course. Although MRI may be an accurate radiological assessment tool, it may not be accessible to the surgeon and the patients, especially in the interior parts of the country. Hence, we sought to compare the evaluation efficacy of MRI versus clinical examination in the diagnosis of fistula-in-ano at a high-volume fistula center. Aim and Objectives: 1. To analyze the sensitivity of clinical findings viz-a-viz, the operative findings in a prospective study in cases of complex fistula-in-ano 2. To analyze the sensitivity of MRI findings viz-a-viz the operative findings in a prospective study in cases of complex fistula-in-ano 3. To compare the sensitivity of clinical findings and MRI findings in cases of complex fistula-in-ano. Study Design: A prospective, observational study with clearance from the Institutional Ethics Committee was undertaken over the period of 2 years in a tertiary care hospital with a sample size of 50. Results: 1. Fifty patients with a mean age of 40.98 years were included in the study 2. Male predominance was seen in the study as 84% were males to 16% females 3. The most common type of fistula-in-ano detected by all the methods of assessment was anterior trans-sphincteric (19 out of 50 by clinical assessment, 16 out of 50 by intra-operative assessment, 14 out of 50 by MRI assessment) 4. Clinical examination was more sensitive (88%) than the MRI examination (72%) in accurately detecting the type of fistula-in-ano 5. The associated abscesses were more sensitively detected by MRI (75%) as compared to clinical examination (31.25%) 6. The most common location of internal openings of fistula-in-ano was 6 o'clock position (27 out of 50 on clinical examination, 27 out of 50 by intra-operative examination, and 21 out of 50 by MRI examination) 7. The locations of internal openings were detected by clinical examination with 100% accuracy. Conclusion: Clinical examination is a sensitive modality for the diagnosis and classification of fistula-in-ano. In places where MRI is unavailable, good technical skills on the part of the surgeon can help in accurately predicting the type and openings of fistula on clinical examination.