Address correspondence to Jacob M. Nieb, MD, MA, Department of Anesthesiology, Northwestern University Feinberg School of Medicine, 251 East Huron St F5-704, Chicago, IL 60611. Address e-mail to [email protected]; [email protected].

Thoracic epidural analgesia is commonly used for postoperative analgesia for abdominal and thoracic surgeries. One complication of thoracic epidural catheter placement is a malpositioned catheter, such as in the subarachnoid, subdural, or intrapleural space. We present a case of unintentional posterior mediastinal catheter placement. The catheter produced a sensory level and analgesic benefit and was only identified incidentally on computed tomography (CT) imaging. This case highlights another possible anatomic location for unintentional catheter placement, which may be more common than reported, as it functioned as an epidural catheter by all clinical metrics and would not have been identified without imaging.