The preemptive visceral analgesic effect of regional nerve block has not been adequately investigated to date. We evaluated the preemptive visceral analgesic effect of thoracic paravertebral block (TPVB) in patients undergoing laparoscopic cholecystectomy (LC) in whom pre-incisional rectus sheath block (RSB) was used to minimize somatic surgical pain. In this prospective, randomized, assessor-blind study, 70 patients scheduled for elective LC were randomly assigned to the pre-TPVB (n=35) or the

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... post-TPVB (n=35) group. Both groups received pre-incisional RSB, and patients in the pre-TPVB group received TPVB before skin incision while those in the post-TPVB group received TPVB after skin closure. The primary outcome was the total rescue analgesic consumption (morphine equianalgesic dose) during the 24 hours post-surgery. The secondary outcomes were the cumulative analgesic consumption and pain intensity for 24 hours after surgery, and adverse events. Pre-TPVB significantly reduced total rescue analgesic consumption (estimated mean [95% confidence interval (CI)]) during the 24 hours after surgery than post-TPVB (16.9 [14.5, 19.3] vs. 25.3 [22.8, 27.7] mg, estimated difference: -8.3 [-11.8, -4.9], P<0.001). The cumulative rescue analgesic consumption was significantly lower in the pre-TPVB group from 2 to 24 hours after surgery (P<0.001). The postoperative pain intensity was significantly lower in the pre-TPVB group as well at 0.5, 1, 2, and 6 hours after surgery. There were no adverse events associated with analgesics, RSB, or TPVB. Pre-incisional TPVB conferred a significant preemptive visceral analgesic effect in patients undergoing LC, and significantly reduced the amount of postoperative opioid consumption.