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Neonatal screening for sickle cell disorders:

Undoubtedly this is the most contentious ethical and legal area. The first difficulty is that the information generated by screening is rarely 100% reliable. Indeed, Russell has argued that the entire debate is surrounded by ‘pseudo-truths’. She writes9 : The straightforward recommendations about screening tests and the information that usually accompanies them are pseudo-truths. They convey rules of thumb developed by experts and leave out the complexities and trade-offs, the mixture of solid information and educated guesses, that have gone into their development. Russell provides the example of the cervical cancer smear and argues that the health services propagate the illusion that screening can lead to a longer life through early detection and treatment. There is, however, a possibility of a wrong result. The cancer might be missed: abnormal cells might be present in the cervix, but may not be included in the scraping of the cervical tissue; or the abnormality may be missed by the technician responsible for examining the thousands of cells on the slide. To those who believe that these dangers can be mitigated by regular testing, another danger arises, that of borderline or false positive due to a noncancerous inflammation or injury to the cervix. The odds of a such false positive result will increase with the number of tests the woman has over her lifetime. To reduce the proportion of false positives in a screening programme, all positive smears may be either repeated, or confirmed by procedures such as colposcopy, with attendant risks to the woman. Nevertheless, with almost all forms of screening, there is a risk of misdiagnosis. This leads to a second consideration. Legally and ethically, education and information giving are essential components of most screening programmes. Those being screened need to be made aware of the limitations of a screening test and, in addition, need to understand the expressions used to convey risk. For example, if a husband and wife discover they both carry a gene for an autosomal recessive disorder, it would be important for them to realise that they have a one-in-four chance of giving birth to a child with that disorder with each pregnancy. Even following diagnostic amniocentesis, there remains a small chance that a normal pregnancy may be terminated or that parents will proceed with an apparently normal pregnancy, only to deliver an affected child.