Question: I have a medical report that lists the procedure as a body box test. I’m new to pulmonology coding, and I’m unfamiliar with the term. How would I report the procedure? Michigan Subscriber Answer: Pulmonologists perform plethysmography to evaluate and diagnose several respiratory diseases, such as chronic obstructive pulmonary disease (COPD), asthma, and pulmonary fibrosis. Providers also use the test to check the patient’s lung function. Plethysmography, which is also known as body box testing, is a procedure where the patient sits in a specially designed room and they breathe into a mouthpiece. The mouthpiece is attached to a measuring device that captures volume and pressure changes as the patient inhales and exhales. The physician may also ask the patient to pant, so the provider can evaluate the airway resistance. The physician analyzes the test results and provides a written report of findings. You’ll assign 94726 (Plethysmography for determination of lung volumes and, when performed, airway resistance) when the pulmonologist performs body box testing if the test is performed in the physician’s office and the physician owns the equipment. If the test is performed in the PFT lab and the physician only interprets the test, you’ll assign 94726 appended with modifier 26 (Professional component) for the professional component. The PFT lab will report the technical component by appending 94726 with modifier TC (Technical component …).