Postoperative Sterile Seroma After Lumbar Spine Surgery: Risk Factors, Clinical Outcomes, and a Proposed Severity Classification

OBJECTIVE: To evaluate the incidence, risk factors, management strategies, and outcomes of postoperative sterile seroma after lumbar spine surgery and to propose a pragmatic severity grading system, the Lumbar Postoperative Sterile Seroma Severity (LPSS) classification. METHODS: We retrospectively reviewed 2,722 consecutive adult patients who underwent lumbar spine surgery between January 2016 and December 2025. Sterile seroma was defined as postoperative wound fluid collection without persistent clinical evidence of infection and with negative bacterial culture when aspiration was performed. Demographic, perioperative, postoperative, and follow-up data were analyzed. Independent predictors were identified using multivariable logistic regression. Seroma cases were categorized according to the LPSS classification: Grade I (mild, observation), Grade II (symptomatic, aspiration), and Grade III (complicated or recurrent, reoperation). RESULTS: , diabetes mellitus, hypoalbuminemia, multilevel surgery, fusion procedures, open approach, operative time >180 minutes, and prolonged drain duration. According to LPSS, 86 patients (58%) were Grade I, 47 (32%) Grade II, and 15 (10%) Grade III. Increasing LPSS grade was associated with progressively longer hospital stay, higher readmission rates, and less favorable follow-up Oswestry Disability Index and visual analog scale scores. CONCLUSIONS: Postoperative sterile seroma after lumbar spine surgery is an underrecognized but clinically relevant complication. Most cases were successfully managed without reoperation. The proposed LPSS classification may help guide treatment stratification and clinical decision-making, but requires prospective external validation.