• screening
• phenylketonuria
• hypothyroidism
• cystic fibrosis
• muscular dystrophy
• growth

• ANSG, Antenatal Subgroup
• CHSG, Child Health Subgroup
• DDH, developmental dysplasia of the hip
• IDT, infant distraction test
• MCADD, medium chain acyl CoA dehydrogenase deficiency
• MS/MS, tandem mass spectrometry
• NHS, National Health Service
• NSC, National Screening Committee

Screening is offered to apparently well individuals to identify those at high risk of a specific condition, for whom early treatment, more effective treatment, or information may be offered in order to improve health outcome or to provide opportunities for informed decision making. By definition, screening tests are not diagnostic tests and therefore cannot separate reliably those with a specific condition from those without. Hence, those with a negative screening result will include some affected individuals, usually referred to as “false negatives”, who may be falsely reassured by the screening result. Conversely, those with a positive screening result will include unaffected individuals, usually referred to as “false positives”, who may be worried unnecessarily or be exposed to the risks of subsequent diagnostic tests. Therefore the threshold for a positive test will be determined by balancing the goals of screening and the perceived disbenefits of missing affected individuals or falsely labelling healthy individuals.²

In the past screening tests have often been introduced as a result of the enthusiasm of one or more individuals without evidence of effectiveness or careful consideration of the wider implications of false reassurance or false labelling. In the UK, this has led to the refinement of the historic “Wilson and Jungner” criteria,³ so that all proposed screening programmes are assessed against specified criteria.⁴