Transversus abdominis plane block in robotic gynecologic oncology: A randomized, placebo-controlled trial

•Preoperative TAP blocks do not decrease narcotic use after robotic surgery in gynecologic cancer.•TAP blocks are safe to use in an analgesic plan for gynecologic cancer patients regardless of BMI.•Narcotic dosing should be adjusted based on age and BMI using a nomogram created by this data set.

ObjectiveAlthough robotic surgery decreases pain compared to laparotomy, postoperative pain can be a concern near the site of a larger assistant trocar site. The aim of this study was to determine the efficacy of transversus abdominis plane (TAP) block on 24-hour postoperative opiate use after robotic surgery for gynecologic cancer.MethodsSixty-four subjects with gynecologic malignancies who were scheduled to undergo robotic surgery were enrolled into the study. They were randomized to receive a unilateral TAP block to the side of the assistant port via ultrasound guidance. The block was comprised of 30 cc of 0.25% bupivacaine with 3 mcg/mL epinephrine or saline. Opiate use was measured and converted into IV morphine equivalents. Patient-reported pain was measured using the Brief Pain Inventory (BPI) and Visual Analog Scale (VAS).ResultsThe treatment group used a mean of 64.9 mg morphine in the first 24 h compared to 69.3 mg for controls (primary outcome, p = 0.52). After age-adjustment, the treatment group used a mean of 11.1 mg morphine less than controls (p = 0.09). Postoperative pain scores assessed by the BPI (6.44 vs. 6.97, p = 0.37) and the VAS (3.12 vs. 3.61, p = 0.30) were equivalent. Block placement was uncomplicated in 98.4% of participants with mean BMI of 35.3 kg/m2. Linear regression revealed an approximate 8.1 mg decrease in morphine equivalents used per additional decade of life (p = 0.0008). There was a positive correlation between the amount of opiates and BMI with an additional 8.8 mg of morphine per 10 kg/m2 increase in BMI (p = 0.0012).ConclusionsTAP block is safe and feasible in this patient population with a large proportion of morbid obesity. Preoperative TAP block does not significantly decrease opiate use. However; based on these data, a clinically useful nomogram has been created to aid clinicians in postoperative opiate-dosing for patients based on age and BMI.