Left-Sided Partial Anomalous Pulmonary Venous Return Uncovered During Central Venous Catheterization in a Patient Undergoing Thoracic Surgery.

Left-sided partial anomalous pulmonary venous return (PAPVR) may remain clinically silent and undiagnosed until incidentally identified, potentially introducing complexity in perioperative assessment and management, particularly in patients with significant comorbidities. We report the case of a 77-year-old male with metastatic colorectal adenocarcinoma and a history of multiple right-sided pulmonary metastasectomies. He underwent a right completion upper bilobectomy. Postoperatively, placement of a central venous line in the left internal jugular vein (selected due to intraoperative accessibility, although the right side is generally preferred for central access) revealed unexpectedly high oxygen saturation levels, prompting an urgent computed tomography angiogram. Imaging confirmed a previously undiagnosed left-sided PAPVR, with drainage of the left upper pulmonary vein into the left jugular vein. The central line was removed and replaced on the contralateral side. No surgical correction was required due to the asymptomatic nature and contralateral location of the anomaly. The patient recovered uneventfully, aside from a brief episode of atrial fibrillation managed conservatively. This case highlights the importance of maintaining clinical awareness of vascular anomalies such as PAPVR in thoracic surgical patients. Incidental findings may have significant implications for central venous access, anesthetic management, and postoperative care. Thorough imaging review and effective interdisciplinary communication are essential to ensure optimal outcomes.