A South Korean prospective study has concluded that an injection of port-site bupivacaine hydrochloride following gynecologic laparoendoscopic single-site surgery (LSSS) does not provide any additive effect in alleviating postoperative umbilical pain.
The study in Obstetrics & Gynecology Science comprised 200 consecutive patients who underwent LSSS between October 2018 and February 2019 at the National Health Insurance Service Ilsan Hospital in Goyang, South Korea.
Patients were alternatively assigned to either the study group, which was 0.25% 10-mL bupivacaine hydrochloride injection at the 1.5-cm umbilical incision site after removal of the wound retractor, or the control group of no injection. In addition, all patients were afforded routine intravenous patient- controlled analgesia (IV-PCA).
The primary outcome was postoperative umbilical pain scores using the visual analog scale (VAS). A trained nurse practitioner blinded to bupivacaine usage collected all the VAS scores.
After adjusting for various confounding variables, differences in postop umbilical pain scores measured at postop 2 to 3 hours, 6 to 10 hours, 1 day and 3 days were non-significant between the two groups.
However, there were significant differences in clinical characteristics between the bupivacaine injection group and the non-injection group: mean age (49.2 and 44.3, respectively), body mass index (BMI) (25.1 and 23.7 kg/m2, respectively) and menopausal status (31 menopausal patients vs. 19 non-menopausal patients, respectively).
The most frequently performed surgery was hysterectomy, representing 126 cases, of which 102 were performed with LSSS and 24 with robot-assisted LSSS.
Mean operative time was 99.4 minutes in the bupivacaine injection group and 109.2 minutes in the non-injection group. But there were no differences in blood loss during surgery, perioperative complications, hospital stay after surgery or time of flatus between the two groups.
In subanalysis, postoperative pain scores were compared between LSSS (n = 157) and robot-assisted LSSS (n = 43) procedures.
After adjusting for the confounding variables of patient age, BMI, parity, menopausal status, American Society of Anesthesiologist (ASA) score, comorbidities, type of surgery performed, need for additional trocar usage, and bupivacaine injection, the pain score at the time of return to the ward was significantly higher in the robot-assisted LSSS cases than in the LSSS cases: 4.6 vs. 4.0 (P = 0.013).
This difference in pain scores persisted at the evening round on the surgery day: 3.9 for robot-assisted LESS compared to 3.3. for LESS (P = 0.021).
“Previous reports on the effectiveness of trocar-site local anesthetic injection in LSSS included only adnexal procedures lasting less than 1 hour, and the role of port-site bupivacaine injection in more complex surgeries with longer operation times accompanied by comparatively higher postoperative VAS scores remains uncertain,” wrote the authors.
As noted, for the current study, the most commonly performed procedure was hysterectomy, not adnexal surgery, and operative time was longer for cases in the current study than in previous studies of adnexal surgeries.
Although bupivacaine hydrochloride is a relatively safe local anesthetic, cardiotoxic and neurotoxic symptoms may occur.
Further studies of various postoperative pain modulators, including liposomal bupivacaine, might help more effectively manage postoperative pain in LSSS. Meanwhile, the authors caution against routine use of postoperative trocar-site bupivacaine injection as a way to reduce postoperative incisional pain.