Seeing the potential areas for reimbursement loss from FESS may start you searching for additional revenue leaks. But in your hunt for the top dollar, don't fall into fraudulent reporting and bill diagnostic sinus endoscopies or polypectomies with sinus procedures. Functional endoscopic sinus surgery (FESS) (31254-31294) includes diagnostic endoscopy (31231-31235) and polypectomy (31237). An otolaryngologist may perform any of the four diagnostic procedures, and based on what he sees, perform a sinus surgery on the same day. In that case, you should report the surgical endoscopy only. Billing both the diagnostic and surgical procedure is unbundling and inappropriate coding.