Background: Breast surgery is associated with postoperative pain, nausea, and chronic pain.  Thoracic paravertebral block (TPVB) and diclofenac are analgesic adjuvant to manage postoperative pain.

Objectives: To compare the efficacy of TPVB and intravenous diclofenac to reduce postoperative morphine consumption after breast surgery.

Methods: Forty-four patients undergoing unilateral mastectomy under general anesthesia were randomly allocated into two groups: group PG (n=22) received TPVB using 0.25% levobupivacaine or group NG (n=22) received diclofenac 150 mg intravenously. The primary outcome was consumption of morphine during the first 24 h postoperatively. Secondary outcomes were consumption of morphine within 48 h postoperatively, numerical rating scale at 24 h and 48 h postoperatively at rest and movement, and complications during the first 24 h postoperatively

Results: Postoperative morphine consumption at 24 h was significantly lower in group NG than group PG (mean difference, MD: -3.30 mg; 95% CI: -6.56 to -0.04; P=0.047) and 48 h (MD: -4.10 mg; 95% CI: -7.64 to -0.56; P=0.024). The numeric rating scale (NRS) at rest was significantly lower in group NG than in group PG at 48 h postoperatively (MD: -0.30; 95% CI: -0.56 to -0.04; P=0.024). The NRS at movement was significantly lower in group NG than group PG at 24 h postoperatively (MD: -1.10 mg; 95% CI: -2.10 to -0.10; P=0.033). There was no complication during the first 24 h postoperatively.

Conclusion: Intraoperative intravenous diclofenac significantly decreased postoperative morphine consumption compared with thoracic paravertebral block in patients undergoing unilateral mastectomy under general anesthesia without postoperative complications.