Infiltration of bupivacaine local anesthetic to trocar insertion sites after laparoscopy: a randomized, double-blind, stratified, and controlled trial.

STUDY OBJECTIVE

To determine if injection of local anesthetic into trocar insertion sites after laparoscopy improves postoperative pain.

DESIGN

A prospective, 2-arm, randomized, double-blind, stratified, and controlled trial (Canadian Task Force classification I).

SETTING

A university-based teaching hospital.

PATIENTS

This study was performed on women who had a laparoscopic gynecologic procedure for benign indications from March 2013 to June 2013. One hundred thirty-five subjects were stratified by chronic pelvic pain or no chronic pelvic pain. Chronic pelvic pain was defined as pelvic pain occurring for 6 months or more in duration. Randomization was performed for this trial, with 68 receiving a bupivacaine block and 67 receiving no bupivacaine block. Of the 71 patients with chronic pelvic pain, 35 patients were in group 1 (i.e., bupivacaine block) and 36 patients were in group 2 (i.e., no bupivacaine block).

INTERVENTIONS

After the laparoscopic surgery was completed, the trocar incision sites were closed. For subjects randomized to receive a local anesthesia block, bupivacaine (0.25%) was injected. Incisions 8 mm or greater were injected with 10 mL 0.25% bupivacaine. Incisions 5 mm or less were infiltrated with 5 mL. Injecting the local anesthetic through all preperitoneal layers provided a full-thickness local injection. Group 2 did not receive a local injection.

MEASUREMENTS AND MAIN RESULTS

At the preoperative suite, the nurses gauged the patient's pain using the Numeric Rating Scale. This score was used as the baseline pain level with which the postoperative pain scores were compared. The primary objective was to measure changes in pain scores, from preoperative to postoperative time frames of 2 to 4 hours, 6 to 8 hours, 18 to 24 hours, and 3 to 7 days postoperatively. These score changes were measured as the main objective. Secondary objectives include estimated blood loss, operating time, length of hospital stay, and histopathologic diagnosis. The hospital personnel caring for the patient during the preoperative and postoperative course were given standard pain evaluation protocols. All study pain evaluators and patients were blinded to treatment assignments throughout the pain assessment process. There were no statistically significant differences in patient characteristics between the 2 treatment groups. No significant difference was found in secondary outcomes including estimated blood loss, length of hospital stay, and histopathologic diagnosis. In general, Numeric Rating Scale pain scores were lower (i.e., less pain) in the "bupivacaine block" group compared with the "no bupivacaine" block group at the following postsurgery time assessments: 2 to 4 hours, 6 to 8 hours, 18 to 24 hours, and 3 to 7 days after surgery. However, the effect was not large enough (<1 point) to show a statistical difference between the treatment groups at any of these postsurgery assessments.

CONCLUSION

The postoperative injection of bupivacaine in trocar port sites did not significantly improve pain scores after laparoscopic gynecologic surgery.