Whether it's to proactively monitor health, diagnose a condition, or assess how well a particular treatment is working, we all undergo a variety of medical tests throughout our lives. While these tests provide valuable information for doctors and patients, they can sometimes carry significant risks, provide ambiguous or incorrect results, or raise more questions than they answer. Contrary to what some may think, medical testing isn't a simple "yes or no" science carried out by computers in a lab—it is a dynamic process that relies heavily on human detective work and interpretation. highlights more than 125 tests performed across a wide range of medical specialties. Each entry in this encyclopedia follows a standardized format that provides readers with information about how, when, and why the test is conducted; the preparation and risks; how results are determined and where errors might occur; and its history. A collection of case studies offers real-world examples of the successes—and shortcomings—of medical testing.