Arterial versus Venous Watershed Localization for Nonpalpable Pulmonary Nodules: A Retrospective Study

Accurate localization of nonpalpable pulmonary nodules is critical for successful surgical resection. This study aimed to evaluate the feasibility and safety of the watershed localization method (WALM), a technique that uses three-dimensional reconstruction and temporary occlusion of watershed arteries or veins combined with indocyanine green (ICG) fluorescence staining for real-time intraoperative navigation. Clinical data were collected from patients who underwent video-assisted thoracoscopic pulmonary wedge resection with arterial-WALM (A-WALM), venous-WALM (V-WALM), or CT-guided localization (CT-GL) from October 2023 to October 2025. Patients were divided into three groups according to the localization method. Perioperative data were compared to evaluate localization efficacy. Both A-WALM and V-WALM were associated with shorter localization procedure time, lower incidence of localization-related complications, and reduced total hospitalization costs as compared with CT-GL. However, they were associated with greater postoperative drainage volume and longer chest tube indwelling time, with no significant differences in other indicators. When the pulmonary fissure is completely developed, the A-WALM approach may be better suited for nodules located in the posterior segment of the right upper lobe, right middle lobe, apicoposterior segment of the left upper lobe, or dorsal and anteromedial basal segments of either lower lobe; V-WALM may be preferable for nodules located in the anterior and lingular segments of the left lung and the posterolateral basal segment of both lungs, while either A-WALM or V-WALM is suitable for nodules in the apical and anterior segments of the right upper lobe. When the pulmonary fissure is incompletely developed, V-WALM may be preferred for localizing nodules in the right middle lobe and apicoposterior segment of the left upper lobe. In conclusion, both A-WALM and V-WALM appear to be feasible intraoperative localization alternatives to CT-GL in selected patients with nonpalpable pulmonary nodules, although they are associated with increased postoperative drainage and longer chest tube duration.