Question: We received a "tracheal aspirate for cytologic evaluation" consisting of 3 cc of fluid and performed an Oil Red O stain. How should we code this? New York Subscriber Answer: You don't mention that you perform a concentration technique before examining the slides, so you should report the cytologic evaluation from the tracheal aspirate as 88104 (Cytopathology, fluids, washings or brushings, except cervical or vaginal; smears with interpretation). If you concentrate the aspirate, you should choose an appropriate cytopathology code, such as 88108 (Cytopathology, concentration technique, smears and interpretation [e.g., Saccomanno technique]). Don't report 88104 in addition to one of the concentration codes 88106-88112, even if you examine direct and concentrated smears -- only report the appropriate concentration code. Because you are evaluating the aspirate for cell changes, not microorganisms, you should report the Oil Red O stain as 88313 (Special stains [list separately in addition to code for primary service]; Group II, all other [e.g., iron, trichrome], except immunocytochemistry and immunoperoxidase stains, each). For instance, Oil Red O may help the pathologist distinguish macrophages indicative of a pulmonary fat embolism.