The members of the Archives' Editorial Board are not philologians nor sticklers for grammatical convention. We are dedicated to getting the message across as clearly and as painlessly as possible.
Painlessly! There's the rub. For the average reader while receiving the message has his ear cocked for discordant notes, which while they may not distort the message fall distractingly on the ear.
"Surgery" is the discipline, the specialty, the career, the department, the craft. It is not the act or the area whereby or wherein surgical techniques are performed. "Operation" is that act, "operating room" is that area, and "operate" is an intransitive verb. Those may be the rules, you say, but why should we stick to them when under the pressures of the give-and-take of hospital life we find communication more convenient if the rules are broken?
The admitting officer makes a decision to call (the department of) surgery.