Fistula-in-ano is a common yet complex anorectal disorder characterized by an abnormal epithelialized tract connecting the anal canal or rectum to the perianal skin. The condition most commonly arises as a sequela of anorectal abscess secondary to cryptoglandular infection, accounting for over 90% of cases (1). Despite being described since the time of Hippocrates, fistula-in-ano continues to challenge surgeons due to its recurrent nature and the risk of postoperative incontinence. The cryptoglandular hypothesis postulates that obstruction of anal glands located at the dentate line leads to abscess formation, which subsequently drains externally, resulting in fistula formation (2). The disease predominantly affects young and middle-aged adults, with a clear male preponderance. The reported global incidence ranges from 1.2 to 8.6 per 100,000 population annually (3). Management of fistula-in-ano aims to eradicate sepsis, eliminate the fistulous tract, prevent recurrence, and preserve sphincter function. However, these objectives are often conflicting, particularly in complex fistulas involving significant portions of the sphincter complex. Recurrence rates ranging from 5% to 30% and postoperative incontinence rates up to 20% have been reported in literature (4,5). Accurate preoperative assessment of fistula anatomy is crucial for optimal surgical planning. Traditional clinical examination, probing, and fistulography have limitations in delineating secondary tracts and sphincter involvement. In recent years, MRI has emerged as the gold standard imaging modality, providing excellent soft-tissue contrast and multiplanar capability (6). Several studies have demonstrated that MRI-guided surgery significantly reduces recurrence rates (7). A wide array of surgical techniques are available, broadly classified into sphincter-cutting and sphincter-saving procedures. While fistulotomy and fistulectomy remain effective for low and simple fistulas, complex fistulas often necessitate sphincter-preserving approaches such as LIFT, advancement flap, or seton placement (8). Despite extensive literature, there remains variability in outcomes due to heterogeneity in fistula anatomy, patient factors, imaging use, and surgical expertise. This study was undertaken to comprehensively evaluate the clinicopathological profile, imaging findings, surgical management, and factors influencing postoperative outcomes in patients with fistula-in-ano. AIMS AND OBJECTIVES 1. To study the demographic and clinicopathological profile of patients with fistula-in-ano. 2. To evaluate the role of imaging modalities, particularly MRI, in preoperative assessment. 3. To correlate MRI findings with intraoperative observations. 4. To analyze outcomes of various surgical treatment modalities. 5. To determine factors influencing postoperative recurrence and anal incontinence.

Study Design A combined prospective and retrospective observational study. Study Setting Department of General Surgery, tertiary care teaching hospital. Study Population Patients diagnosed with fistula-in-ano presenting during the study period. Sample Size 100 patients. Inclusion Criteria • Age ≥18 years • Clinically diagnosed fistula-in-ano • Patients consenting for surgical intervention and follow-up Exclusion Criteria • Malignancy-related fistula • Rectovaginal fistula • Patients lost to follow-up Clinical Evaluation All patients underwent detailed history taking, per-rectal examination, and proctoscopy. Data regarding symptoms, duration, prior abscess, comorbidities, and previous surgeries were recorded. Imaging MRI pelvis with fistulography protocol was performed in all patients. Findings included fistula type, internal and external openings, secondary tracts, abscesses, and relation to sphincter complex. Surgical Management Procedures were individualized: • Fistulotomy • Fistulectomy • Seton placement • LIFT procedure • Advancement flap repair Follow-Up Patients were followed up at regular intervals up to 6 months. Continence was assessed using CCIS. Recurrence was defined as reappearance of symptoms or fistula after complete healing. Statistical Analysis Data were analyzed using descriptive statistics. Chi-square test was used to assess associations. A p-value <0.05 was considered statistically significant.

A total of 100 patients with fistula-in-ano fulfilling the inclusion criteria were evaluated and managed during the study period. The observations are presented under demographic profile, clinical characteristics, imaging findings, operative details, and postoperative outcomes. 1. Demographic Profile Age Distribution The age of patients ranged from 19 to 75 years, with a mean age of 39.95 ± 13.25 years. The majority of patients belonged to the productive age group (21–40 years). Table 1: Age Distribution of Patients Age Group (years) Number of Patients Percentage (%) <20 1 1.0 21–30 32 32.0 31–40 23 23.0 41–50 20 20.0 >50 24 24.0 Total 100 100 Age distribution, demonstrating a peak incidence in the 21–30 and 31–40 year age groups. Gender Distribution Out of 100 patients, 84 were male and 16 were female, giving a male-to-female ratio of 5.25:1, highlighting a marked male predominance. Table 2: Gender Distribution Gender Number Percentage (%) Male 84 84.0 Female 16 16.0 sex-wise distribution indicating higher prevalence among males. Geographical Distribution A slightly higher proportion of patients belonged to urban areas. Table 3: Place of Residence Residence Number Percentage (%) Urban 57 57.0 Rural 43 43.0 2. Clinical Presentation The most common presenting symptom was persistent perianal discharge, followed by pain and bleeding. Table 4: Clinical Symptoms Symptom Number of Patients Percentage (%) Discharge 96 96.0 Pain 41 41.0 Bleeding 6 6.0 Mean duration of discharge was 14.29 ± 13.84 months, indicating chronic disease at presentation. 3. History of Perianal Abscess A prior history of perianal abscess was present in 94% of patients, supporting the cryptoglandular theory. 4. Associated Comorbidities Comorbid conditions were present in 12% of patients. Table 5: Distribution of Comorbidities Comorbidity Number Percentage (%) Diabetes Mellitus 8 8.0 Hypertension 3 3.0 Tuberculosis 1 1.0 None 88 88.0 5. Per-Rectal Examination Findings • Anal tone was normal in 90% of patients. • Single external opening was noted in 83% of cases. • Discharge was elicited on PR examination in 69% of patients. Table 6: Per-Rectal Examination Findings Parameter Finding Percentage (%) Anal tone Normal 90 Increased 10 External openings Single 83 Multiple 17 Discharge on PR Present 69 Absent 31 6. Imaging Findings (MRI) MRI pelvis was performed in all patients and provided excellent delineation of fistula anatomy. Table 7: MRI Classification of Fistula (St. James’s Classification) Grade Type of Fistula Number (%) Grade I Simple intersphincteric 32 Grade II Intersphincteric with abscess/branch 14 Grade III Transsphincteric 28 Grade IV Transsphincteric with abscess 18 Grade V Supralevator/extrasphincteric 8 MRI findings correlated with intraoperative findings in: • External opening: 92% • Internal opening: 89% 7. Surgical Procedures Performed Table 8: Surgical Modalities Used Procedure Number Percentage (%) Fistulotomy 42 42.0 Fistulectomy 26 26.0 Seton placement 18 18.0 LIFT 9 9.0 Advancement flap 5 5.0 8. Postoperative Outcomes Recurrence Overall recurrence rate was 12%. Table 9: Recurrence According to Type of Fistula Fistula Type Recurrence (%) Intersphincteric 4 Transsphincteric 12 Suprasphincteric 30 Extrasphincteric 33 Incontinence Postoperative incontinence occurred in 9 patients (9%), mostly mild (flatus or liquid stool). Table 10: Incontinence by Surgical Procedure Procedure Incontinence (%) Fistulotomy 14 Fistulectomy 8 Seton 6 LIFT 0 Advancement flap 0

Fistula-in-ano remains a challenging anorectal condition due to its varied anatomy, high recurrence rates, and the constant need to balance disease eradication with sphincter preservation. The present study provides a comprehensive analysis of clinicopathological characteristics, imaging correlation, and surgical outcomes in 100 patients. The mean age of 39.95 years and strong male predominance observed in this study are consistent with global epidemiological trends, as reported by Hämäläinen et al. and Parks et al. (1,2). The predominance in young and middle-aged males may be attributed to higher anal gland density, occupational strain, and lifestyle factors. The high incidence (94%) of previous perianal abscess strongly supports the cryptoglandular hypothesis, reaffirming the importance of early and adequate drainage of anorectal abscesses to prevent fistula formation (3). MRI pelvis demonstrated excellent accuracy in identifying fistula anatomy, internal openings, and secondary extensions. The strong correlation between MRI and intraoperative findings in this study aligns with Buchanan et al., who showed that MRI-guided surgery significantly reduces recurrence rates (4). MRI was particularly valuable in complex fistulas, suprasphincteric extensions, and recurrent disease. Surgical management was individualized based on fistula type. Fistulotomy remained the most commonly performed procedure due to its simplicity and high success rate in low fistulas. However, it also accounted for the highest incontinence rates, particularly when used in high fistulas. These finding echoes previous reports by Garcia-Aguilar et al. (5). Sphincter-saving procedures such as LIFT and advancement flap showed zero incontinence but a slightly higher recurrence rate, emphasizing the trade-off between continence preservation and complete eradication of disease. Diabetes mellitus emerged as a significant risk factor for recurrence, likely due to impaired wound healing and persistent infection. Overall, recurrence was significantly higher in complex, high-grade fistulas and patients with comorbidities. These findings reinforce the necessity of meticulous preoperative assessment, proper case selection, and long-term follow-up. The present study highlights important aspects of fistula-in-ano management in a tertiary care setting. The demographic profile observed aligns with previous studies reporting male predominance and peak incidence in the fourth decade of life (9). MRI proved to be an invaluable tool, with high concordance with operative findings, corroborating results from Buchanan et al., who demonstrated reduced recurrence with MRI-guided surgery (7). The ability of MRI to detect secondary tracts and abscesses is critical in preventing incomplete surgery. Recurrence rates in this study were comparable to reported literature (10–20%) (10). Complex fistulas and comorbidities such as diabetes were significant predictors of recurrence. Sphincter-saving procedures, while reducing incontinence, showed a slightly higher recurrence rate, emphasizing the trade-off between disease eradication and functional preservation. Incontinence remains a feared complication. The 9% incontinence rate observed aligns with previous reports (11). Careful patient selection and judicious choice of surgical technique are paramount.

Fistula-in-ano requires meticulous evaluation and individualized surgical planning. MRI plays a pivotal role in accurate delineation of fistula anatomy and should be considered essential in complex and recurrent cases. Surgical outcomes are influenced by fistula complexity, patient comorbidities, and procedure type. Balancing recurrence prevention with continence preservation remains the cornerstone of successful management.

1. Parks AG, Gordon PH, Hardcastle JD. A classification of fistula-in-ano. Br J Surg. 1976;63:1-12. 2. Ramanujan PS, et al. Anorectal abscess and fistula. Dis Colon Rectum. 1984. 3. Hämäläinen KP, et al. Incidence of anal fistula. Int J Colorectal Dis. 1998. 4. Sangwan YP, et al. Factors influencing recurrence. Dis Colon Rectum. 1994. 5. Buchanan GN, et al. MRI of fistula-in-ano. Lancet. 2003. 6. Halligan S, et al. Imaging of fistula-in-ano. Radiology. 2006. 7. Buchanan GN, et al. Effect of MRI on outcome. Dis Colon Rectum. 2002. 8. Bleier JIS, Moloo H. Current management. Clin Colon Rectal Surg. 2011. 9. Read DR, et al. Epidemiology of anal fistula. Am J Surg. 1979. 10. Williams JG, et al. Management guidelines. Gut. 2007. 11. Garcia-Aguilar J, et al. Incontinence after fistula surgery. Dis Colon Rectum. 1996.