Ask Dr. Z

If catheter placement in the thoracic aorta is documented with angiography, what vessel findings need to be documented in order to code for 36221? Do we need findings of the left common carotid and vertebral if unilateral left is done? If both vessels aren't documented on, do we add a -52 modifier to 36221? Also would you add a -52 modifier to 36221 when aortic arch angiography is performed with further selective catheter placement into the subclavian (36215) and upper extremity angio (75710) (due to the catheter placement in the aorta being bundled into 36221)?