Simple Anal Fistula: Clinical Criteria for Diagnosis and Local Anesthesia with Conscious Sedation for Surgery - An Observational Study

To evaluate (i) acceptability of surgery for simple anal fistula under local anesthesia with conscious sedation by the patients and (ii) accuracy of a set of clinical criteria for diagnosing the condition. Methods: Simple anal fistula was diagnosed using a set of clinical criteria. The patients underwent surgery under local anesthesia with conscious sedation. Intravenous paracetamol, diclofenac sodium, and midazolam were administered as adjuvants. Fistulotomy with/without marsupialization was performed in most patients. Clinical diagnosis was matched with operative findings. Results: Among 193 patients presenting with anal fistula, 61 were diagnosed as simple anal fistula and were scheduled for surgery under local anesthesia. One patient was found to have a complex anal fistula during intraoperative assessment and surgery was deferred. The operation was completed under local anesthesia with conscious sedation for 58/60 (96.7%) patients. Acceptability of the procedure was assessed with the patients’ satisfaction score on a visual analog scale (VAS) and their willingness to undergo fistula surgery under local anesthesia again if required. The median (interquartile range) VAS score for patients’ satisfaction was 10 (9- 10). All patients expressed willingness to undergo fistula surgery under local anesthesia again if required. The clinical criteria were successful in diagnosing simple anal fistula in 58/61 (95.1%) patients. The remaining three patients had a high intersphincteric fistula (1) or a blind sinus (2). Conclusions: Acceptability of surgery for simple anal fistula under local anesthesia with conscious sedation was excellent. The proposed clinical criteria were highly accurate in diagnosing simple anal fistula.