Ultrasound-guided regional anesthesia requires the anesthesia provider to interpret new information. This article reports on the case of a 38-year-old man scheduled for a fifth metacarpal fracture repair. Ultrasound nerve examination revealed abnormal pathology of the axillary brachial plexus consisting of an increased volume of the terminal nerves of the brachial plexus. Ultrasound scanning initiated the subsequent diagnosis of multifocal motor neuropathy. Regional anesthesia was abandoned in favor of general anesthesia. Ultrasonography training needs to be expanded in the coming years to include awareness of the abnormal pathology, as it might impact the choice of anesthetic procedure and patient outcome.