BACKGROUND CONTEXT Multiple-level lumbar fusion surgery is associated with prolonged duration of surgery and significant blood loss, which are deemed significant risk factors for postoperative SSI. Controlling the blood loss and improving local resistance to pathogens is extremely valuable to reduce perioperative complications, including SSI, and speed up recovery after surgery. Concerns regarding the safety profile of TXA, whether it increases the incidence of thromboembolic events, such as deep vein thrombosis (DVT), pulmonary embolism (PE), and myocardial infarctions (MI), have been raised frequently, especially for the patients who have accompanying cardiovascular and cerebrovascular diseases, which are relatively common in patients with degenerative spinal disease. Additionally, it is strongly debated whether the usage of vancomycin powder can induce culture-negative seroma formation and affect bone healing. Hydrogen peroxide (H2O2) is an inexpensive and readily available option whose hemostatic and antiseptic properties have been separately confirmed in several previous studies. However, whether H2O2 can integrate the advantages of vancomycin and TXA in controlling blood loss and postoperative SSI simultaneously after lumbar spine surgery has not been explored, neither have its complications. PURPOSE This study aimed to explore the safety and efficacy of H2O2 in controlling blood loss and SSI after multi-segmental lumbar spine surgery. STUDY DESIGN/SETTING Retrospective case-control study. PATIENT SAMPLE A total of 2,626 patients who underwent multi-segmental lumbar spinal surgery between January 2015 and January 2018 were included in this study. According to whether H2O2 irrigation was applied, they were divided into control group (1,345 patients) and experimental group (1,281 patients).The inclusion criteria were: (1) patients were diagnosed with thoracic and/or lumbar degenerative diseases, such as spinal canal stenosis, disc herniation, spondylolisthesis, and/or degenerative scoliosis; (2) patients treated with multilevel (operated level > 2) posterior lumbar interbody fusion (PLIF) with or without posterolateral fusion. The exclusion criteria were: patients diagnosed with spinal fracture-dislocation, infection, tuberculosis, tumor, congenital spinal deformity or received revision surgery; patients with a coagulation or hemoglobin dysfunction before surgery; dura tear accompanied by cerebrospinal fluid leakage detected intraoperatively; the perioperative use of hemostatic agents such as TXA or treatment with antifibrinolytic drugs. OUTCOME MEASURES The primary outcome evaluated was the incidence of SSI. The definition of SSI including superficial and deep infection after lumbar spinal surgery was derived from the guidelines published by the U.S. Centers for Disease Control and Prevention. Superficial infection is defined as occurring within 30 days after surgery, involving only the incision skin and subcutaneous tissue. Deep infection is defined as occurring within 1 year after operation, characterized by superficial infection, the involving fascia and myometrium. Besides the demographic parameters, the laboratory examination results and surgery related information such as operative time, numbers of operated levels, intraoperative blood loss, postoperative drainage, postoperative SSI and extubation time were recorded. The perioperative complications including pneumocephalus, symptomatic DVT, PE and MI were included in the evaluation. METHODS A standard posterior midline incision and exposure was applied; and irrigation with 1 L of saline was performed before skin closure in all patients. For the experimental group, the incision was soaked with 50 mL of 3% H2O2 solution for 30 s before the saline irrigation. RESULTS No significant differences were seen regarding demographic parameters, laboratory examination results, comorbidities and surgical related information. The extubation time and postoperative drain collection were lower in the experimental group (3.6±0.5 days vs 4.1±0.6, p=0.402; 251.8±67.5 vs 291.8±71.3, p=0.013). In the control group, the rate of SSI was 2.4% (32/1345), including 17 superficial wound infections and 15 deep wound infections. In the experimental group, the SSI rate was 1.4% (18/1281), including 15 patients with superficial wound infection and three with deep wound infection. Staphylococcus aureus was the most common organism, especially in the experimental group (66.7% vs 50%). There was no significant difference between both groups in the perioperative complications such as hematencephalon, DVT, PE and MI (p>0.05, respectively). Pneumocephalus was not observed in either group. CONCLUSIONS The application of H2O2 in PLIF does not increase the perioperative complications such as hematencephalon, DVT, PE, MI, and especially pneumocephalus; it also reducing the blood loss and SSI after surgery, which is quite promising for patients with a high risk of thromboembolic events and beneficial for controlling the increasing number of vancomycin-resistant bacteria. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.