Tendon sheath injections given in a single tendon sheath, or ligament, aponeurosis with a therapeutic drug is coded as what?

The procedure of tendon sheath injections is coded based on the specifics of the injection. When referring to coding for injections administered to a single tendon sheath, ligament, or aponeurosis, the appropriate code is 20550. This code indicates a single injection performed at one site, which fits the description provided in the question.

Using this code correctly represents the service rendered, ensuring that all billing and coding guidelines are adhered to. For multiple injections at different sites, other codes would apply, but since the question specifically notes a single tendon sheath or location, 20550 is the only applicable choice. This helps in accurately documenting the level of service provided and maintaining proper reimbursement from payers.