Beyond body mass index: how vascular morphology influences the risk of thrombosis associated with peripherally inserted central catheters in patients with cancer

Background: Peripherally inserted central catheters (PICCs) are widely used in cancer patients but carry a significant thrombosis risk. While body mass index (BMI) is recognized as a thrombogenic factor, the role of vascular morphology remains unclear. Materials and Methods: A total of 338 adults with cancer requiring PICC insertion at our hospital were prospectively enrolled between January 11 and 30 December 2023. All study participants underwent ultrasound-guided PICC placement using a 4-Fr single-lumen catheter. Patients were monitored for thrombosis by serial ultrasonography. Demographic, clinical, and vascular characteristics were compared between patients who developed thrombosis and those who did not. Results: PICC-related thrombosis developed in 35.5% of patients and was asymptomatic in 75.8% of cases. Bivariate analysis showed that BMI, vessel depth, arm circumference, vessel diameter, and blood flow velocity on the first post-insertion day were associated with the risk of thrombosis (P<0.05). Multivariate regression analysis identified shallower vessel depth (<1.0 cm, odds ratio [OR] 0.324, 95% confidence interval [CI] 0.120–0.874, P = 0.026) and smaller post-insertion vessel diameter (reduction <0.6 cm, OR 0.025, 95% CI 0.001–0.550, P = 0.019) as independent risk factors for thrombosis. Blood flow on the first post-insertion day was significantly slower in the thrombosis group (13.4 cm/s vs. 14.9 cm/s, P = 0.007). Blood flow velocity increased with increasing BMI, peaking at a BMI of 28.3 kg/m 2 before declining beyond this threshold. Conclusion: Low BMI and poor vascular morphology increase the risk of PICC-related thrombosis. The influence of BMI is likely mediated by vascular remodeling, with blood flow velocity peaking at 28.3 kg/m 2 before declining, reflecting a compensatory hemodynamic balance.