| faecal occult blood test | <investigation> A chemical test that measures the presence of fresh or decomposed blood. Blood may arise from bleeding anywhere along the gastrointestinal tract, from the mouth to the anus. An easy to perform colourmetric test. Occult means hidden. (08 Mar 2000) |
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| developer | 1. One who, or that which, develops. 2. <photography> A reagent by the action of which the latent image upon a photographic plate, after exposure in the camera, or otherwise, is developed and visible. Source: Websters Dictionary (01 Mar 1998) |
| occult blood | Blood that is in the faeces or vomitus that is not obvious by general inspection. Used as a diagnostic screening test for colon cancer. Tests for occult blood are generally colourimetric. Stool sample will turn blue when a particular chemical reagent is mixed with the specimen on test paper. Kits for measuring occult blood in the stools are now available at most drug stores. (27 Sep 1997) |
| occult | Obscure, concealed from observation, difficult to understand. (18 Nov 1997) |
| occult bleeding | See: occult blood. (05 Mar 2000) |
| occult border of nail | The proximal border of the nail entirely covered by the nail wall. Synonym: margo occultus unguis, occult border of nail. (05 Mar 2000) |
| occult carcinoma | <tumour> A small carcinoma, either asymptomatic or giving rise to metastases without symptoms due to the primary carcinoma. (05 Mar 2000) |
| occult fracture | A condition in which there are clinical signs of fracture but no X-ray evidence; after 3 or 4 weeks X-ray imaging shows new bone formation. (05 Mar 2000) |
| occult hydrocephalus | <neurology> A brain disorder caused by blockage of the flow of cerebrospinal fluid (CSF), with enlargement of the ventricles of the brain (keep the pressure normal) and compression of brain tissue. Brain atrophy is the result. In this condition the CSF is produced normally but not reabsorbed. Symptom onset is gradual. A key feature is dementia. Treatment is surgical (VP shunt). (13 Nov 1997) |
| Almen's test for blood | Glacial acetic acid, gum guaiac solution, and hydrogen peroxide are added to an aqueous suspension of the suspected stain; if occult blood or blood pigment is present, a blue colour develops. Synonym: guaiac test, Schonbein's test, van Deen's test. (05 Mar 2000) |
| ABO blood group | <haematology> The major human blood type system which describes the oligosaccharide glycoprotein antigens found on the surface of human blood cells. According to the type of antigen present, a person may be assigned a blood type of A, B, AB or O. A second type of antigen, the Rh factor, renders a positive or negative blood type. The ABO blood group system is important because it determines who can donate blood to or accept blood from whom. Type A or AB blood will cause an immune reaction in people with type B blood and type B and AB blood will cause a reaction in people with type A blood. Conversely, type O blood has no A or B antigens, so people with type O blood are universal donors. And since AB blood already produces both antigens, people who are type AB can accept any of the other blood types without suffering an immune reaction. (04 Jul 1999) |
| arterial blood | Blood that is oxygenated in the lungs, found in the left chambers of the heart and in the arteries, and relatively bright red. (05 Mar 2000) |
| arterial blood gas | A test which analyses arterial blood for oxygen, carbon dioxide and bicarbonate content in addition to blood pH. Used to test the effectiveness of respiration. Acronym: ABG (17 Oct 1997) |
| blood | <haematology> Considered a circulating tissue composed of a fluid portion (plasma) with suspended formed elements (red blood cells, white blood cells, platelets). Arterial blood is the means by which oxygen and nutrients are transported to tissues, venous blood is the means by which carbon dioxide and metabolic by-products are transported for excretion. (05 Jan 1998) |
| blood agar | <cell culture> An agar-based medium which hasbeen enriched with sterilised, defibinated blood (sheep, rabbit or horse). It is used for primary plating andsubculturing, especially to determine bacterial haemolysis. (09 Oct 1997) |