Ultrasound-Guided Caudal Epidural Block Versus Saddle Block for Anorectal Surgeries: A Prospective Randomized Comparative Study

Background Anorectal surgeries are commonly performed as ambulatory procedures requiring effective perineal anesthesia, hemodynamic stability, adequate postoperative pain control, and early mobilization to facilitate same-day discharge. Saddle block provides dense sacral anesthesia but is often associated with sympathetic blockade, hypotension, motor impairment, and urinary retention. Ultrasound-guided caudal epidural block (USG-CEB) has emerged as a reliable alternative that allows selective sacral nerve root blockade with potentially improved recovery characteristics. However, direct comparative evidence between USG-CEB and saddle block in adult anorectal surgeries remains limited. Aim and objectives To compare USG-CEB with saddle block in adult patients undergoing elective anorectal surgery. The primary objectives were to evaluate time to mobilization and time to first rescue analgesia. Secondary objectives included assessment of onset of sensory blockade, intraoperative hemodynamic changes, time to voiding, requirement for supplemental local infiltration, and patient satisfaction. Materials and methods This prospective randomized controlled study included 59 adult patients scheduled for elective anorectal surgery. The trial was registered in the Clinical Trials Registry of India (CTRI/2020/01/022896) and also obtained approval from the Institutional Ethics Committee (approval number: VMMC/ANESTH/2019/01). Patients were randomized into two groups: Group C (USG-CEB) and Group S (saddle block). Ultrasound-guided blocks were performed using a high-frequency linear probe (L13-3Ns, 3-13 MHz). Rescue analgesia was administered when the visual analogue scale (VAS) score was ≥four, using intravenous tramadol 50 mg, repeatable every eight hours as required. Postoperative assessments were conducted by a blinded observer. Data were analyzed using appropriate statistical methods. Continuous variables were expressed as mean ± standard deviation and compared using the independent t-test. Categorical variables were analyzed using the chi-square test. Effect sizes (Cohen’s d) and 95% confidence intervals were calculated for primary and key secondary outcomes. A p-value <0.05 was considered statistically significant. Results Patients in the USG-CEB group demonstrated significantly earlier mobilization (5.82 ± 0.71 h vs. 6.95 ± 0.60 h, p<0.001) and earlier time to voiding (4.95 ± 0.73 h vs. 6.82 ± 0.71 h, p<0.001) compared to the saddle block group. Time to first rescue analgesia was longer in the USG-CEB group (5.00 ± 0.95 h vs. 4.45 ± 0.74 h, p=0.021). However, sensory onset was faster in the saddle block group (9.83 ± 1.42 min vs. 12.86 ± 1.84 min, p<0.001). Hemodynamic parameters were more stable in the USG-CEB group. Conclusion USG-CEB is an effective alternative to saddle block for anorectal surgery, offering a favorable recovery profile characterized by earlier mobilization, earlier voiding, and stable hemodynamics. However, these advantages should be weighed against a slower onset of anesthesia and the need for supplemental analgesia in some patients. The clinical significance of these findings may vary across practice settings, and anesthetic technique should be individualized.