Bevel direction of epidural needles reliably predicts direction of catheter placement and contrast spread in human cadavers: Results of a pilot study

Study Objective: To confirm the relationship between bevel orientation, catheter direction, and radiopaque contrast spread in the lumbar region. Design: Pilot cadaver study. Setting: Anatomy laboratory of a university hospital. Measurements: Cadavers were randomized to two groups of 4 cadavers each. In Group 1, needle bevel direction at epidural entry was cephalad; in Group 2, it was caudad. After placement of each epidural catheter in L₄-L₅ interspace, 2 mL of radiopaque contrast was injected and a lumbar posterior-anterior radiograph was obtained. Catheter direction and direction of radiopaque contrast spread were collected. Main Results: Due to the inability to access the epidural space secondary to surgical changes in the lumbar spine, one cadaver in the cephalad group was excluded. In 7 of 7 (100%) cadavers, the catheter tip direction according to the radiograph corresponded directly with bevel direction. Conclusions: A strong relationship exists between bevel orientation and catheter direction; however, catheter position does not reliably predict the direction in which the injected fluid spreads in all cadavers.