Enough time had passed since the patient’s previous colonoscopy that she met the criteria to undergo another, said Dr. Steven Itzkowitz, a gastroenterologist at the Icahn School of Medicine at Mount Sinai in New York. She was in “reasonably good health,” and the risks of the procedure — bleeding, reaction to anesthesia, perforation of her colon — were fairly low. But she was 85. And she would need to briefly discontinue the blood thinners she took because of the cardiac stents keeping her arteries open; doing so could increase the risks. Had Itzkowitz and his patient faced this decision five years ago, he might have scheduled the screening “without even thinking about it,” he said. But recent research has shown, again, that the benefits of a repeat colonoscopy are slim after age 75. Now, he said, “I’m saying to myself, ‘What are we accomplishing here?’” He’s not the only doctor — or patient — having second thoughts.…