operating surgeon; surgeon performing an operation
Refers specifically to the surgeon who actually performs the surgery, as opposed to an assistant or a surgeon in general. Often used in medical contexts or news reports.
See also: 外科医
The operating surgeon explained the procedure to the patient before the surgery.
He serves as the operating surgeon for cardiac surgery at that hospital.
Compound of 執刀 (しっとう, 'holding a scalpel; performing surgery') + 医 (い, 'doctor').