To evaluate whether a serratus anterior plane block (SAPB) is more effective than a local infiltration anesthesia (LIA) with an equal dose and same anesthetic performed by the surgeon, as an adjuvant to treat postoperative pain after unilateral mastectomy.~Primary endpoint: the use of opioid's in the postoperative period. Secondary endpoint: Numerical Pain Rating Scale (NPRS) score recorded at the 2nd, 8th, 16th, 24th hour after surgery. 0 means no pain and 10 is the worst pain imaginable. In addition at the same time, we will look to the degree of arm mobilization where there will be 3 possible groups: 1. restricted, 2. fair mobilization and 3. free mobilization.~There are 2 treatment arms: 1st arm is the standard therapy, namely the local infiltration anesthesia. 2nd arm is the experimental arm, namely the SAPB. Patients are randomised into each arm after screening.
To evaluate whether a serratus anterior plane block (SAPB) is more effective than a local infiltration anesthesia (LIA) with an equal dose and same anesthetic performed by the surgeon, as an adjuvant to treat postoperative pain after unilateral mastectomy.