Correlation between transcutaneous perianal ultrasonography findings and preoperative findings of fistula in ano

Background: Fistula in ano is a common and challenging condition in colorectal surgery. Accurate diagnosis is crucial for effective treatment. This study evaluates the efficacy of transcutaneous perianal ultrasonography (TPUS) in diagnosing fistula in ano, comparing its findings with per-operative observations. Methods: This cross-sectional observational study was conducted at Shaheed Suhrawardy Medical College, Dhaka, over six months. Fifty patients diagnosed with fistula in ano were included. TPUS was used to detect fistula tracts and internal openings, with findings compared to per-operative observations. Data were analyzed for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TPUS. Results: TPUS demonstrated high sensitivity in detecting fistula tracts (97.80%) and internal openings (95.45%). However, specificity was lower for both fistula tracts (20.00%) and internal openings (33.33%). The PPV and NPV for TPUS in detecting fistula tracts were 91.67% and 50.00%, respectively, and 91.30% and 50.00% for internal openings. The overall accuracy of TPUS was 90.00% for fistula tracts and 88.00% for internal openings. Conclusions: TPUS is a highly sensitive diagnostic tool for detecting fistula tracts and internal openings in patients with fistula in ano. Despite its lower specificity, TPUS can be an effective component of a multimodal diagnostic approach. Combining TPUS with other diagnostic methods can enhance the accuracy of diagnoses and improve patient outcomes.