BACKGROUND: Interpectoral and pectoserratus plane blocks are fascial plane blocks that are used during anterolateral superficial chest wall surgery. However, the true analgesic efficacy of these blocks in oncological breast surgery is unclear because of the diversity of breast-surgery procedures. The primary hypothesis of this study was that these blocks reduce the incidence of acute pain. METHODS: This double-blinded, multicenter, randomized controlled study included 185 patients. Patients were randomized equally into two groups at a 1:1 ratio according to the type of interfascial injection received (ropivacaine vs. saline). The incidence of analgesic rescue during the first 3 postoperative hours was the primary outcome measure. RESULTS: The authors enrolled 182 women. The analgesic rescue incidence was lower in the ropivacaine group. Interpectoral and pectoserratus plane blocks with ropivacaine had an incidence of analgesic rescue of 43 % (n = 37) versus 61 % (n = 50) in patients given the placebo (relative risk = 0.70
95 % CI = 0.52 to 0.94
p = 0.02). Interpectoral and pectoserratus plane blocks with ropivacaine are associated with a 30 % reduction in the use of rescue analgesics. CONCLUSIONS: Interpectoral and pectoserratus plane blocks reduced the incidence of analgesic rescue and reduced the postoperative pain score to the mild range after oncological breast-conserving surgery and sentinel lymph-node biopsy.