Intrathecal Morphine Versus Transversus Abdominis Plane Block in Robotic Colorectal Surgery

Intrathecal morphine (ITM) and transversus abdominis plane (TAP) block are both used for analgesia after minimally invasive colorectal surgery, but direct comparisons in robotic surgery are limited. We compared them for postoperative opioid consumption and pain after robotic colorectal resection.

We conducted a two-hospital retrospective cohort study of patients undergoing robotic colorectal resection between January 2022 and December 2023 who received either ITM or TAP block. Propensity score matching (1:1) balanced age, sex, body mass index, American Society of Anesthesiologists physical status, and procedure category. The two prespecified co-primary outcomes were postoperative opioid consumption (oral morphine equivalents) on postoperative day (POD) 0 and mean POD 0 Numeric Rating Scale pain score. Within-pair comparisons used paired t-tests, each co-primary tested at a two-sided alpha of 0.025.

Of 198 patients (136 ITM, 62 TAP), 120 were matched (60 pairs). POD 0 opioid consumption did not differ (mean paired difference -9.6 mg, 95% confidence interval [CI] -25.3 to 6.1; P = 0.22) and remained nonsignificant through 48 h (P = 0.98). POD 0 pain was lower with ITM (-1.32, 95% CI -2.14 to -0.49; P = 0.002), consistent across all sensitivity analyses. Intraoperative opioid consumption was lower with ITM (-5.2 mg, 95% CI -10.0 to -0.4; P = 0.03). Recovery milestones did not differ.

Postoperative opioid consumption was similar between ITM and TAP block, whereas POD 0 pain was lower with ITM. ITM was also associated with lower intraoperative opioid use. The early analgesic benefit did not extend to cumulative postoperative opioid use within a multimodal pathway.