Background: Persistent post-mastectomy pain has serious physical and psychological effects on the lives of patients. The PECS block combines motor and sensory nerve blocks and is distinct from sympathetic block. This study aimed to compare intraoperative with preemptive ultrasound guided (US guided) PECS block effect on controlling acute postmastectomy pain.

Methodology: Sixty cases arranged for elective simple mastectomy were involved in this randomized, single-blind, controlled trial. Cases were randomized equally into three groups. Group C (the control group): received no block, Group D (direct PECS group): received direct pecs block by surgeon after closure of pectoralis muscle under direct vision and before skin closure and Group U (US guided PECS group): received US guided PECS block done after induction and before skin incision.

Results: Morphine consumption in 1st 24h postoperative was significantly lower in
U group compared to C and D groups (P value