The Mrs. Hufnagel Chronicles, Part 10

St. Eligius just can't get rid of Mrs. Hufnagel, who demands a new doctor upon readmission.

Mrs. Hufnagel (Florence Halop) lays down the law.

As Dr. Elliott Axelrod (Stephen Furst) discharges Mrs. Hufnagel (Florence Halop) at the end of "The Children's Hour", he prescribes phenylbutazone to help with her phlebitis and her aches and pains. In the next episode, "Dr. Wyler, I Presume", Axelrod, a first-year resident, is excited to be paged by name to the E.R. until he learns that the patient demanding to see him is none other than Mrs. Hufnagel, who is now unconscious and has a nearly-empty bottle of phenylbutazone on her. Dr. Philip Chandler (Denzel Washington) rejects Elliott's plea to take the patient off his hands, and orderly Warren Coolidge (Byron Stewart) refuses Elliott's order to relay instructions for the nurse before

She had been taking four times the prescribed dose, but nonetheless demands a new physician who isn't trying to kill her. The duty falls on Dr. Jack Morrison (David Morse), whom Hufnagel recognizes as the one with the red knapsack and the kid who never says much on rounds. She questions Morrison about his medical education (which he obtained in Mexico), and then is horrified to learn that the doctor has ordered a barium enema for her: "N-O. Nobody touches the booty."

According to Wikipedia, phenylbutazone is no longer approved for human use in the United States, but is commonly prescribed to horses. Hufnagel was admitted with gastrointestinal bleeding, which can be a side effect...in horses.

It will turn out that Hufnagel is right to question Morrison's medical education; in the next episode ("Whistle, Wyler Works"), it will be revealed that Jack fast-tracked his medical degree, and is not actually qualified to practice medicine. He will have to redo medical school while doing his residency and raising his infant son by himself; this lasts into season four. Fortunately, his diagnostic skills improve considerably once he actually learns some medical knowledge.