Definition of Screening

Screening refers to physical examination, laboratory tests, or radiology studies performed on asymptomatic patients in the hopes of finding subclinical disease. Early detection refers to discovering a condition before symptoms have appeared. Screening and early detection are important because intervention before a disease develops or early in the course of the disease can reduce the incidence of the disease (example: reduced cases of congenital rubella syndrome following routine immunization of women of childbearing age), and can reduce morbidity and mortality from the disease (example: reduced invasive cervical cancer and cervical cancer mortality following use of Pap screening to detect cervical dysplasia). Both quality and duration of life may be improved, and healthcare costs reduced. Diagnosis refers to the confirmation of a medical disorder in symptomatic patients: by the time symptoms are present, the disease is often more advanced and treatment is less likely to be successful.