healthscreening

Health screening, or screening, is the systematic use of tests, examinations, or procedures to identify individuals who appear healthy but may have an undiagnosed disease or risk factor. The aim is to detect disease at an early stage, when treatment is more effective, or to identify risk that can guide preventive actions. Screening is not diagnostic; a positive result requires confirmatory testing and appropriate follow-up care.

Screening programs can be organized at the population level (population-based or organized screening) or offered opportunistically during routine care. Common examples include cancer screening (such as mammography for breast cancer, colonoscopy or stool-based tests for colorectal cancer, and cervical cancer screening with cytology or HPV testing), while noncancer screening includes blood pressure, cholesterol, glucose, and infectious disease testing (for example HIV), as well as newborn screening for metabolic and genetic conditions.

Key considerations in screening include the performance characteristics of tests (sensitivity, specificity), potential harms from false positives or overdiagnosis, and the balance of benefits and costs. Ethical and practical requirements include informed consent, equitable access, follow-up diagnostic testing, and treatment availability. Screening programs rely on evidence of net benefit and are guided by national or international recommendations that consider age, sex, risk factors, and the starting and stopping ages and intervals.

Effectiveness varies by condition and program; some, like cervical cancer and colorectal cancer screening, have shown mortality benefits in many settings, while others show limited or uncertain impact. Challenges include ensuring adequate participation, minimizing harm from overdiagnosis, and addressing disparities in access.

Newborn screening uses simple tests soon after birth to identify treatable conditions before symptoms appear. The concept of screening has roots in the Wilson and Jungner criteria from the mid-20th century and remains a reference framework for evaluating programs.