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Diagnostic tests

Specimen jar containing three female Japanese Bitterlings, 1930-1980

Specimen jar containing three female Japanese Bitterlings, 1930-1980

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Doctors use tests to communicate with the patient, observe his or her body, and support their diagnosis. Many tests are now available to practitioners. They may indicate the presence of a germ or abnormal cells, or the lack or excess of certain chemicals. Genetic tests now detect disease present in the body. They even detect risk factors which indicate the likelihood of a healthy person developing a disease such as breast cancer later in life.

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For instance, doctors can use three types of tests if a patient suffers from suspected stomach ulcers: stool or blood tests; endoscopes to look at the inside of the stomach; or a Breathalyser to detect Heliobacter pylori, a bacterium suspected of causing stomach ulcers. Tests can also take place outside the laboratory. Simple tests now allow women to detect pregnancy without sending urine samples to a laboratory. Expert patients measure blood sugar levels and cholesterol themselves using home testing kits.

Interpretation

However, tests are not always secure and unambiguous. Problems arise interpreting the results, or considering the risks or consequences for the patient’s treatment. For example, in a cervical biopsy or ’smear test’ doctors look for abnormal cells in the tissue sample taken from the female patient.

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These determine whether she is at risk of cervical cancer. However, the interpretation raises questions such as when does a cell count as abnormal? And how many cells have to look different from the norm to count as significant? What does a test actually test for? Another interpretation problem arises if medical scientists disagree on the value of a test. The famous IQ tests in psychology are designed to uncover a person’s intelligence. However, some scientists doubt their value. They argue the IQ test does not reflect intelligence, only how well people can do IQ tests.

Ethical issues

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Ethical issues such as immediate health risks and later consequences must be considered when using medical tests. The prenatal amniocentesis of fluid to investigate the presence of genetic disorders in the foetus carries a small risk of miscarriage. Parents and practitioner must consider this risk. What are the consequences of knowing the outcomes of a test? When does it benefit the patient to know of the presence of risk factors? Early indication of the presence of risk factors may help patients change their lifestyles. This minimises their chances of developing the condition for which they are at risk. However, knowledge of the presence of risk factors may diminish a person’s quality of life.

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Bibliography

R Rapp, Testing Women, Testing the Fetus: The Social Impact of Amniocentesis in America (New York: Routledge, 1999)

T Pinch, ‘Testing - 1,2,3 testing: toward a sociology of testing’, Science, Technology and Human Values, 18/1 (1993), pp 25-41

J Carson, ‘Army alpha, army brass, and the search for army intelligence’, Isis, 84/2 (1993), pp 278-309

S J Reiser, ‘The science of diagnosis: diagnostic technology’, in W F Bynum and R Porter (eds), Companion Encyclopedia of the History of Medicine, Vol. 2 (London: Routledge, 1993), pp 826-51

H P Bayon, ‘Ancient pregnancy tests in the light of contemporary knowledge’, Proceedings of the Royal Society of Medicine, 32 (1938-39), pp 1527-1538

J Burstein and G D Braunstein, ‘Urine pregnancy tests from antiquity to the present’, Early Pregnancy: Biology and Medicine, 1 (1995), pp 288-296

A B Davis, Medicine and Its Technology: An Introduction to the History of Medical Instrumentation (Westport, CT: Greenwood Press, 1981)

R Gottlieb, ‘The Bitterling test for pregnancy’, Canadian Medical Association Journal, 34/4 (1936), pp 431-32

I Moore, 'Peroral Endoscopy: An Historyical Survey From Its Origins to the Present Day', Journal of Laryngology and Otology, 41 (1926), 277-98

 

Glossary:

Germ

Tiny organisms that cause disease. 'Germ' is now a term that is applied loosely to many micro-organisms, including bacteria, viruses and fungi.

Endoscope

an instrument to look at the internal parts of the body. The modern endoscope is a flexible, fibreglass instrument that can be swallowed by a patient or introduced through a tiny incision in the body.

Bacteria

Micro-organisms which can cause disease but have an important role in global ecology.

Cervix

Neck of the uterus, projecting downwards into the vagina.

Foetus

The name given to the embryo during the later stages of development. In human reproduction it refers to an unborn child from its eighth week of development.

Miscarriage

A miscarriage is where a pregnancy ends before 24 weeks. Miscarriages occur in between ten and twenty per cent of all pregnancies.