Right Upper Lobe Venous Drainage Posterior to the Bronchus Intermedius: Preoperative Identification by Computed Tomography

Background Anatomical variations of the pulmonary vessels relevant to pulmonary surgery are of concern to thoracic surgeons. Among such variations, the right upper lobe vein posterior to the bronchus intermedius (UVPBI) has received little attention thus far. Methods Chest computed tomographic images and medical records of 725 patients were retrospectively reviewed. The frequency, drainage pattern, diameter, and associated anatomical characteristics of the UVPBI were assessed, and our right thoracotomy cases with the UVPBI were examined. Results The UVPBI was found in 41 (5.7%) of 725 computed tomography cases, and in 9 (3.9%) of 230 right thoracotomy cases. Three UVPBI drainage sites were observed: (1) the superior pulmonary vein group, 55%; (2) the inferior pulmonary vein group, 41%; and (3) the superior segmental vein group, 4%. The diameter of the UVPBI at the level of the bronchus intermedius ranged from 1 to 7 mm (4.1 ± 1.6 mm). The diameter of the UVPBI in the superior pulmonary vein group was significantly greater than that in the inferior pulmonary vein group (p< 0.01). The prevalence of a central vein was 43.9% for all UVPBI cases and 15.8% for large UVPBI cases (≥ 5 mm in diameter). Of the 9 right thoracotomy patients, 1 suffered UVPBI injury; this patient’s UVPBI was not identified either preoperatively or intraoperatively. Conclusions The UVPBI is not as rare as was previously believed. It can be a main drainage route of the right upper lobe. Preoperative identification of this venous variation by computed tomography is useful for safe and accurate surgical procedures.