From Wikpedia:

Physician–patient privilege is a legal concept [...] that protects communications between a patient and their doctor from being used against the patient in court.

What am I missing here? Clearly both cannot be true at the same time.

EDIT: nevermind, I found the answer further down on the page:

In the United States, the Federal Rules of Evidence do not recognize doctor–patient privilege.

At the state level, the extent of the privilege varies depending on the law of the applicable jurisdiction. For example, in Texas there is only a limited physician–patient privilege in criminal proceedings, and the privilege is limited in civil cases as well.