The Contrast None is identified by letter "Z" and occupies the 5th position in the ICD10-PCS procedure code structure.
Below a selection of ICD 10 PCS codes related to B31CZ
Fluoroscopy Bi Ext Carotid w L Osm Contrast, Laser Intraop
Fluoroscopy Bi Ext Carotid w Oth Contrast, Laser Intraop
Fluoroscopy of Bilateral External Carotid Arteries
Fluoroscopy of Bi Ext Carotid using H Osm Contrast
Fluoroscopy of Bi Ext Carotid using L Osm Contrast
Fluoroscopy Bi Ext Carotid w H Osm Contrast, Laser Intraop
Fluoroscopy of Bi Ext Carotid using Oth Contrast