A general surgeon asked me to assist in a colectomy where he had inadvertently nicked a mesenteric artery. I entered the case and did a direct repair of the artery. Should I bill as his assistant or co-surgeon and what modifier should I use?
In this case, you would not bill as an assistant or a co-surgeon. You would bill for the work you did, direct repair of an abdominal vessel (35221), without a modifier. A colectomy code is not valued to include repair of an artery, so billing as assistant or co-surgeon would not be appropriate. You will bill only for the specific work that you did: repairing the artery.