My doctor will not do a colonoscopy as long as all other tests are negative (no blood in stool, certain enzymes OK). I have heard of a couple of perforated intestines recently (both in the UK) so I go along with this. My doctor will also not do a manual examination of the prostate provided the PSA is normal, no blood/proteines in urine, the patient is not having urinary trouble, and the ultrasonic exam is OK. (He loves his ultrasonic machine, whichg is switched on all day and ready to go. Gets me on it every time I'm there. Hopefully one day his lovely assistant will be allowed to apply the jelly.)
And never forget the most important question a doctor should ask a patient: "What did your parents die of ?"