During a physical exam, doctors pick up a lot from their patients including patients bacteria. To keep infections from spreading, physicians try to always wash their hands between exams. But they don't always scrub their stereoscopes.

To see just how much bacteria these instruments gather, doctors examined seventy one patients, using sterile stereoscopes and gloves. After each exam, researchers collected samples from the stereoscope surface and tube, as well as four parts of the physicians gloved hands: the fingertips, backs, and two locations on the palm.

The fingertips became by far the most bacterially contaminated. But the runner-up was the stereoscope surface, which gathered more microbes than the palms or the backs of the hands. The study is in Mayo Clinic Proceedings. 

Although fingertips picked up more than five times as much bacteria as stereoscopes did, doctors reduce that contamination before seeing the next patient by cleaning their hands. According to the study authors, stereoscopes should get the same treatment. Then the only thing to fear is the stereoscopes icy temperature.