California Subscriber
Answer: If the patient was in observation for a reason - and not just for the NST - then you can bill both the observation care (99217-99220) and the NST (59025, Fetal non-stress test).
Be sure, however, that the physician performed an NST and did not just connect external electrodes to monitor fetal heart rate or contractions. For you to bill an NST, the patient must record when she feels the baby moving. (For more on coding NSTs, see the January 2004 Ob-Gyn Coding Alert article "Think You Can Use 59025 for Labor Checks? Think Again" on page 1.)