Unexpected Position of a Hemodialysis Catheter

Central venous catheterization is frequently employed to obtain urgent hemodialysis access, and catheter malposition due to unrecognized venous anomalies is an underappreciated complication.We describe the case of a 77-year-old man with end-stage renal disease and an extensive vascular access history who required a temporary hemodialysis catheter after thrombosis of his arteriovenous graft.The catheter was placed uneventfully in the left internal jugular vein under ultrasound guidance, but control radiography showed its tip lying in the left hemithorax, and blood gas analysis from the catheter was compatible with arterial blood.Contrast-enhanced computed tomography revealed the catheter tip within the left superior pulmonary vein, which drained into the left brachiocephalic vein, consistent with partial anomalous pulmonary venous return, a rare congenital anomaly usually discovered incidentally.The catheter was removed without complications, and the patient was managed without hemodialysis until his arteriovenous graft was successfully salvaged two days later.This case highlights that an atypical catheter trajectory combined with an arterialized blood gas does not imply arterial puncture and that anomalous venous anatomy should be in the differential diagnosis.