Preoperative care refers to health care provided before a surgical operation. Preoperative care aims to do whatever is right to increase the success of the surgery.
At some point before the operation, the healthcare provider will assess the fitness of the person to have surgery. This assessment should include whatever tests are indicated, but not include screening for conditions without an indication.
Immediately before surgery the person's body is prepared, perhaps by washing with an antiseptic, and if needed, their anxiety is addressed to make them comfortable.