screening

Systematic search for evidence of a disease, or of conditions that may precede it, in people who are at risk but not suffering from any symptoms. The aim of screening is to try to limit ill health from preventable diseases that might otherwise go undetected in the early stages. Examples are hypothyroidism and phenylketonuria, for which all newborn babies in Western countries are screened; breast cancer (mammography) and cervical cancer; and stroke, for which high blood pressure is a known risk factor.

The criteria for a successful screening programme are that the disease should be important and treatable, the population at risk identifiable, the screening test acceptable, accurate, and cheap, and that the results of screening should justify the costs involved.