Douglas Harper's Etymology Dictionary
pre-op
1913 as short for pre-operative (preparation).
Wiktionary
pre-op
a. preoperative alt. preoperative n. 1 (context medicine English) A preoperative patient or procedure. 2 (context LGBT English) A preoperative transman or transwoman
Usage examples of "pre-op".
Goodman injected intravenously a 6 cc bolus of Innovar, the same droperidol and fentanyl combination that had been used as the pre-op medication.
Every Saturday night the pre-op transsexual in the apartment below would get maudlin and play torch songs until four in the morning.