(covers information from several alternate timelines)
Reader tube with removed implant
McCoy uses a reader tube to monitor Sulu's recovery
Alternate reality design
A reader tube was a multipurpose piece of mid-23rd century medical technology, specifically designed for field use, and typically issued with a standard medkit. It was also commonly used in sickbay surgeries as well. (TOS: "Space Seed", "Journey to Babel", "Return to Tomorrow", "The Lights of Zetar")
The reader tube, which was similar in function to a medical scanner, was used while placed near the patient's skin, and would display multicolored lights representing numerous body readings, including the heart rate, pulse rate, body temperature, and blood pressure. It was also capable of detecting the toxin level in a patient's body. (TAS: "The Infinite Vulcan") The reader tube could also be used as a surgical device. (TOS: "For the World is Hollow and I Have Touched the Sky")
In the alternate reality created by Nero's temporal incursion, Doctor Leonard McCoy used a reader tube to examine a Enterprise crew member in the aftermath of the destruction of Vulcan. (Star Trek)
In 2268, Doctor Leonard McCoy used a reader tube during his emergency heart surgery on Ambassador Sarek. (TOS: "Journey to Babel") Later that year, Spock used a reader tube to remove Dr. McCoy's instrument of obedience. McCoy in turn would also use a reader tube to remove Natira's instrument of obedience. (TOS: "For the World is Hollow and I Have Touched the Sky")
In 2269, Dr. McCoy used a reader tube to monitor Hikaru Sulu's progress after recovering from the poison of the retlaw plant on Phylos. (TAS: "The Infinite Vulcan")
