In simple words: This code is used when the anesthesiologist personally performs the anesthesia for your surgery and is present in the operating room for the entire procedure.

This modifier is used to document that the anesthesiologist personally performed the entire anesthesia service for the surgical procedure. It also applies when the anesthesiologist continuously supervises a student anesthetist during the procedure, or when the procedure involves the anesthesiologist with one resident. To bill with modifier AA, the anesthesiologist must continuously monitor a single case and be physically present in the operating room during the entire procedure.

Example 1: A patient undergoes a hernia repair. The anesthesiologist personally administers and monitors the anesthesia throughout the procedure, so modifier AA is appended to the anesthesia code., A student anesthetist administers anesthesia under the continuous, in-room supervision of an anesthesiologist for a knee replacement. The anesthesiologist remains present for the duration of the procedure. Modifier AA is appended., An anesthesiologist is assisted by a single resident during a heart surgery. The anesthesiologist is continuously present and supervises the resident's involvement throughout the entire procedure. Modifier AA is appended.

Documentation should clearly reflect that the anesthesiologist personally performed the anesthesia service for the entire duration of the procedure and remained physically present in the OR. Any involvement of a student or resident must also be documented, as well as the level of supervision provided.