Chapter 20: Diagnostic investigations
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Principles of care
Cancer nurses and nursing staff play a key role within the diagnostic testing process because they often identify the need for diagnostic investigations, initiate the collection of specimens and assume responsibility for timely and safe transportation to the laboratory (Higgins [65]). Nurses are vital in the screening and surveillance of disease progression and may undertake ongoing surveillance procedures.
Methods of investigation
Initial examination
The initial assessment of the patient will determine the potential diagnostic tests or samples that are required. The patient's clinical history and/or symptom progression will determine the need for further diagnostic or surveillance tests.
Cytology
Cytology is the study of the cell, its structure, structural transformations, molecular biology and cell physiology. The specimen can be a fine‐needle aspiration, a sample of body fluid or a scrape/brush. The specimen is placed onto a glass slide and examined for the presence of abnormal cells. This includes benign, pre‐cancerous or cancer cells. The test can also be used to diagnose infective processes (Chernecky and Berger [26]).
Histology
Histology is the study of cells and tissues within the body. It also studies how the tissues are arranged to form organs. The histological focus is on the structure of individual cells and how they are arranged to form the individual organs. The types of tissues that are recognized are epithelial, connective, muscular and nervous (Kierszenbaum and Tres [79], Mescher [97]).
The tissues are examined under a light microscope where light passes through the tissue components after they have been stained. As most tissues are colourless, they are stained with dyes to enable visualization. An alternative is the electron microscope in which the cells and tissue can be viewed at magnifications of about 120,000 times (Kierszenbaum and Tres [79], Mescher [97]).
