Role of Local Infiltration of Bupivacaine Versus Bupivacaine Plus Ketamine In Reducing Postoperative Pain Score After Anal Fistula Surgery

Syed Ali Haider, Muhammad Abid Owais, Khalid Ahmed

  • Muhammad Abid Owais Department of Surgical Sciences Baqai Medical University Karachi



To compare the postoperative pain scores in patients with local infiltration of bupivacaine versus bupivacaine plus ketamine after anal fistula surgery.

Study design

Comparative study.

Place & Duration of study

Department of Surgical Sciences, Baqai Medical University Karachi, from July 2015 to December 2020. 


The study included 126 patients who had fistulotomy or fistulectomy under spinal anesthesia. Patients were divided into two groups. In Group A, postoperatively, patients received 2ml of 0.5% bupivacaine plus 1ml of normal saline while those in Group B had infiltration of 2ml of 0.5% bupivacaine plus 1ml of ketamine at dentate line. Postoperative pain was assessed using visual analogue scale (VAS) at 6, 12, and 24 hours following the end of procedure. Mean pain scores among groups were compared using student t test.


The pain scores on VAS at 6 hours and 12 hours postoperatively were less in Group B that was statistically significant (p=0.000 and 0.006 respectively), whereas the score at 24 hours, despite being low in same group but not significant (p=0.071). Overall the mean pain score was less in Group B than Group A.


Local infiltration of bupivacaine plus ketamine is better at ameliorating postoperative pain after anal fistula surgery compared to bupivacaine alone.

Key words

Fistula-in-ano, Fistulotomy, Fistulectomy, Postoperative pain, Anal surgery.