What is the ruling on a male doctor treating a Muslim woman?

If a female specialist doctor is available, she should examine the patient. If not, then a trustworthy non-Muslim female doctor. If not, then a Muslim male doctor. If not, then a non-Muslim male doctor. The doctor should only examine what is necessary, avert his gaze, and the treatment should be in the presence of a mahram or husband or a trustworthy woman, fearing khalwa (unlawful seclusion).