Anatomy and Surgical Implications of the Lumbar Epidural Venous Plexus: A Risk Zone Framework.

The lumbar epidural venous plexus (LEVP) is a predominantly valveless venous network within the epidural space and an important source of intraoperative bleeding during lumbar spine surgery. Although its anatomy is well described, its practical relationship to surgical exposure and bleeding behavior remains underemphasized. This narrative review synthesizes the anatomical organization, communications, spatial relationships, and variability of the LEVP and translates these findings into a procedure-oriented framework of venous bleeding risk zones. Based on the relationship of the plexus to the posterior longitudinal ligament (PLL), dura mater, nerve roots, lateral recess, and intervertebral foramen, four clinically relevant zones are proposed: the ventral epidural, lateral recess/axillary, foraminal, and posterior epidural zones. Each zone is associated with distinct surgical exposures, characteristic bleeding patterns, technical pitfalls, and hemostatic considerations. This framework emphasizes that epidural venous bleeding is not random but follows reproducible, anatomy-driven patterns. Recognizing the LEVP as an organized and surgically relevant system may improve anatomical anticipation, intraoperative decision-making, and procedural safety during lumbar spine surgery.