What is the test for a medical malpractice judgment based on incomplete information?

In Chattu v. Pankratz, [1990] B.C.J. No.704 (B.C.S.C.), the court stated at p.8: Judgment implies the weighing, assessing or evaluating of such information as may be available. Here the defendant exercised his judgment on incomplete information, because he failed to carry out a full and careful examination…I conclude that the defendant was in breach of the duty he owed to the plaintiff to make a full and careful examination, and that if he had made a full and careful examination he would almost certainly have diagnosed vascular impairment, or arterial insufficiency…as a probable cause of the plaintiff’s symptoms.