BACKGROUND: Metabolic and bariatric surgery is an effective intervention for severe obesity, known for improving comorbidities such as type 2 diabetes, hypertension, and hyperlipidemia. However, its association with kidney stone formation remains uncertain. This study investigates the relationship between bariatric surgery and kidney stone prevalence using data from NHANES 2015-2018. METHODS: We conducted a cross-sectional analysis of 8,087 participants from NHANES (2015-2018). Bariatric surgery and kidney stone history were self-reported. Logistic regression models adjusted for demographic, clinical, and lifestyle factors were used to evaluate associations. Stratified analyses explored effect modification by subgroups. RESULTS: Kidney stones were more prevalent among participants with bariatric surgery (26.57%) compared to those without (10.92%, P <
0.001). Bariatric surgery was associated with increased odds of kidney stones in the crude model (OR: 2.95, 95% CI: 1.57-5.55) and adjusted models (OR: 2.69, 95% CI: 1.27-5.70). Subgroup analyses highlighted stronger associations among females and participants with moderate physical activity. CONCLUSION: Metabolic and bariatric surgery is linked to an elevated risk of kidney stones, influenced by demographic and clinical factors. Personalized counseling on hydration and dietary modifications is essential for mitigating this risk.