A diagnostic test is any kind of medical test performed to aid in the diagnosis of detection of a suspected disease or condition. This is different from a screening test which is used when not when a disease or condition is suspected, but when people are considered to be at high risk of developing a disease or condition. Diagnostic test are usually performed after a positive screening test to establish a definitive diagnosis. They are also offered to individuals who have some indication, be it a symptom, sign or a history of a particular disease or condition. For example; a physician performing a biopsy on a woman with a lump in one of her breasts is a diagnostic test for suspected breast cancer. A post-menopausal woman undergoing a routine mammogram without any breast cancer symptoms is a screening test for breast cancer.
Screening tests are offered to asymptomatic people who may or may not have early disease or disease precursors and test results are used to guide whether or not a diagnostic test should be offered. Diagnostic tests are offered to people who have a specific indication of possible illness (a history, symptom, sign or positive screening test result) to determine whether or not they have the disease in question. Also, a screening test helps to identify individuals who are not exhibiting any symptoms (asymptotic) and determine if they are at risk of developing a disease or condition.
Characteristics of a Diagnostic Test * The cutoff for a positive result is precisely defined, with stress being laid on diagnostic precision and accuracy * They cost more because of the accuracy that is required. * The test provides for a definitive diagnosis * The test is often invasive, such as a lumbar puncture to test for meningitis * They are used for individuals who are symptomatic
Characteristics of a Screening Test * The cutoff for a positive result is extremely sensitive and