You can't code to get paid, which means you shouldn't go to the LDC to find a payable code.
Why is the screening being done? He has to be looking for something, what is he screening for? Is he screening for malignant tumors, is he screening for an infectious disease or is he screening for a condition that wasn't found, etc?
You need to be more specific. If that is the only reason for the service documented then this is a non-billable exam due to lack of documentation/medical necessity.
Medicare covers a screening Ultrasound of the aorta as part of the Welcome to Medicare benefit. The patient must be at risk, the test must be ordered during the Welcome to Medicare exam, use G0389 as the CPT®. Diagnosis would be V81.2