BACKGROUND: Optimizing intravascular volume (IV) before surgery is crucial for patients undergoing resection of functioning pheochromocytomas and paragangliomas (PPGLs). While point-of-care ultrasound (POCU) is a noninvasive technique to assess IV, the use of POCU to evaluate preoperative IV and its relationship to perioperative adverse outcomes (PAOs) remains largely unexplored. METHODS: We conducted a prospective cohort study including patients who underwent PPGL resection following preoperative α-blockade. Preoperative IV was assessed using inferior vena cava (IVC) ultrasound and clinical parameters. We used logistic regression models to examine the associations between preoperative IV and intraoperative hemodynamic instability (IHI), perioperative organ dysfunction (POD), and PAO. We also compared the predicting abilities of IVC ultrasound measurements and clinical parameters for PAOs. RESULTS: A total of 80 patients were recruited and analyzed. The study population carried a heavy comorbidity burden (median age-adjusted Charlson Comorbidity Index 4), thus the median duration of preoperative α-blockade was 60 (30, 98) days. Based on IVC ultrasound, 27 patients were classified as having appropriate volume status and 53 as inappropriate volume status. We found no significant association between IVC ultrasound assessed IV status and IHI, POD, and PAO. Furthermore, neither IVC ultrasound assessments nor clinical parameters could discriminate PAOs, and the predictive performance of the two methods did not differ significantly. However, this finding should be interpreted with caution, as the study was likely to be underpowered (enrolled 80 of 364 planned patients, 22%). CONCLUSION: In this study with a sample size of 80 patients, no independent association was found between preoperative IVC ultrasound measurements and PAOs in patients undergoing PPGL resection with an extended duration of preoperative α-blockade preparation [60 (30, 98) days]. The utility of point-of-care IVC ultrasound in guiding preoperative volume optimization for these patients merits further exploration.