Blood test

“ The efficiency of the rapid test is therefore not invalidated. It is, nevertheless, in the present state of knowledge, a wise precaution to perform the direct test between patient and donor in addition to the group test when circumstances permit. It is essential when the patient is suffering from any form of blood disease. It is unnecessary when the transfusion is to be performed as a life-saving operation in hæmorrhage or shock. ”

“ I believe that in time we shall be able to refine this test to tell the exact individual, too.
"What is this principle? It is that the hemoglobin or red colouring-matter of the blood forms crystals. That has long been known, but working on this fact Dr. Reichert and Professor Brown of the University of Pennsylvania have made some wonderful discoveries.
"We could distinguish human from animal blood before, it is true. But the discovery of these two scientists takes us much further. ”

“ A serum specific for rabbit’s blood serum was therefore prepared, and the stains dissolved and tested as described above. No sign of precipitate was obtained within thirty minutes after applying the test and evidence was therefore given that the stain certainly did not consist of rabbits’ blood. On the other hand, [Pg 166] a serum made specific for human blood gave an immediate precipitate with the solution of the stain, which, therefore, in all probability consisted of human blood. ”

“ Supposing that a donor actually of the same group as the patient is wanted, then the reverse test must be performed in addition, that is to say, the corpuscles of the patient must be tested against the serum of the donor. If both tests are negative, then donor and patient are proved to be of the same group. The method of direct test cannot be applied in an emergency owing to the loss of time involved; it is better, therefore, that anyone who intends to be ready to perform a blood transfusion should always have serum of Groups II and III immediately available. ”

“ Where stains have been found upon the clothes or on a weapon in possession of an accused person and have been proved to consist of blood, the defence has [Pg 160] frequently been set up that they were caused by the blood from a sheep that had been killed or from handling game.
Ten years ago, prior to the discovery of the serum test, it would not have been possible, except in the cases where the blood corpuscles could be examined, to prove or disprove this except by corroborative evidence. ”

“ The test was positive.
"What is it?" gasped Seabury hoarsely, leaning over close.
"This," exclaimed Kennedy, "is the famous Abderhalden test—serum-diagnosis—discovered by Professor Emile Abderhalden of Halle. It rests on the fact that when a foreign substance comes into the blood, the blood reacts, with the formation of a protective ferment produced as a result of physiologic and pathologic conditions.
"For instance," he went on, "a certain albumin always produces a certain ferment. ”

“ Don’t you see that it gives us an infallible test for blood stains. Come over here now!” He seized me by the coat-sleeve in his eagerness, and drew me over to the table at which he had been working. “Let us have some fresh blood,” he said, digging a long bodkin into his finger, and drawing off the resulting drop of blood in a chemical pipette. “Now, I add this small quantity of blood to a litre of water. You perceive that the resulting mixture has the appearance of pure water. The proportion of blood cannot be more than one in a million. ”

“ Precipitins find their greatest usefulness in legal medicine and in food adulteration work. As was noted above, if animals, rabbits for example, are immunized with the blood of another animal (human beings) precipitins are developed which are specific for the injected blood with proper dilution. This forms an extremely valuable means of determining the kind of blood present in a given spot shown by chemical and spectroscopic tests to be blood and has been adopted as a legal test in countries where such rules of procedure are applied. ”

“ Of all systems, the blood appears to have been the most conservative and to have retained most fully its ancestral characters. It is on this account that blood tests are so valuable in revealing relationships that can scarcely be determined in any other way. ”

“ This test rests upon the principle that in the serum of an animal treated with human blood or albumin there are developed antibodies having a strong specific hæmolytic or precipitating action upon human blood or albumin. ”

“ The opinion of the majority of conservative men seems to be that while vaccine therapy is undoubtedly an important addition to our [p. 202] methods of treatment of bacterial infections, particularly of those which are strictly local, yet the value of the opsonic index in measuring resisting power or as an aid to diagnosis and guide to treatment is still sub judice.
IX. TESTS FOR RECOGNITION OF BLOOD
1. Guaiac Test.—The technic of this test has been given (p. 89) . It may be applied directly to a suspected fluid, or, better, to the ethereal extract. ”

“ The squares represent the calculated specificity and sensitivity of one test within a study; the black line is the 95% confidence interval. Tests with a * in front were excluded from the meta-analysis, because of high risk of bias or complete data was not available.Forest plots of sensitivity and specificity of RDTs with microscopy of placental blood as reference test. The squares represent the calculated specificity and sensitivity of one test within a study; the black line is the 95% confidence interval. ”

“ Similarly, we are satisfied that the test chosen to measure petitioner's blood-alcohol level was a reasonable one. Extraction of blood samples for testing is a highly effective means of determining the degree to which a person is under the influence of alcohol. See Breithaupt v. ”

“ He further advised that it is the customary administrative practice among municipalities to allow blood to be taken only by a doctor. In all cases a competent technician is required to make the laboratory analysis incident to the test. We were assured that in no instance had a municipality or the state police permitted the test to be made without these precautions.↑ National Safety Council, Accident Facts 1956, 43-71.↑ Governors' Conference Committee, Report on Highway Safety (Nov. 1956) ”

“ It is only a white count or a differential count or an examination for malaria that is required.
As a practical point it is very rare that a red count is indicated. There is one point not sufficiently recognized by physicians and that is that a routine blood examination is not apt to be as carefully conducted as one calling for a specific feature. Without disparaging the necessity of routine examination of urine as well as blood it is a fact that the internist who knows what he wants gets better results from the laboratory man. ”

“ It was with mounting admiration that he followed her new project in examining blood samples. As they came up from the clinic, she sorted the specimen tubes at once, putting a tiny snip of yellow Scotch tape under the label of each sample that belonged to a patient with the new undiagnosed disorder.
Then, after the requested hemoglobin, blood sugar and other standard tests had been run, she retrieved the samples from the technicians, grouped them in a special rack and devoted every spare minute to further examination. ”

“ This practice was obviously a dangerous one, since even by the modern methods of examination it is not always a simple matter to be sure of the fact.
Until a comparatively recent date the tests for blood-stains were based upon bringing the colouring matter of the blood into solution and applying chemical tests to establish its identity.
[Pg 158] The necessity for scientific proof of the presence of blood-stains is shown by numerous cases in which stains of similar colour have at first been attributed to blood. ”

“ After death the amount of blood sometimes seems to be increased, and sometimes, as in “pernicious anaemia,” it is certainly diminished. But the high counts of red corpuscles which are occasionally reported as evidence of plethora or increase of the total blood are really only indications of concentration of the fluid except in certain rare cases. It is necessary, therefore, in examining blood diseases, to confine ourselves to the study of the blood-unit, which is always taken as the cubic millimetre, without reference to the number of units in the body. ”

“ The method should have a sufficiently low limit of detection to differentiate exposed from nonexposed workers. A method developed when biological monitoring reference levels were higher may be inadequate for measuring exposures at and below the current guidelines.
4. Limitations of the sample matrix and its affect on the analysis need to be assessed. In general, blood serum and urine specimens require different sample preparations and may require separate methodologies to eliminate matrix effects. ”

“ If it is necessary to make a complete examination, it is rather difficult to draw up the blood in the pipettes, dilute it, and then get material for fresh blood preparations and films without undue squeezing, which is to be avoided. ”

“ When the combined percentage of globulins and serum albumin is subtracted from the total proteid percentage we have the percentage of nucleo-proteid.
Tests for Blood.—Very important in tests of the urine are those for blood. With an unaided eye a smoky colored urine, more or less reddish-brown in color, is suggestive in cases of haematuria, while in haemoglobinuria we usually have a more or less porter-colored, turbid fluid which, however, shows a clear haemoglobin-tinged fluid when centrifuged to throw down the haemoglobin casts and granular débris of the disintegrated red cells. ”

“ Pure blood is regarded as one of the great essentials of health, and much study has been devoted to that important part of the human system. The most perfect apparatus for examining the blood is considered none too good, but how often in the average hospital are tests applied to the materials from which blood is made? Are all butchers and bakers and grocers and dairymen so honorable that occasional analysis of the products supplied is quite unnecessary? ”

“ We merely take a sterilized swab of cotton on the end of a wire, rub it gently over the surface of the throat and tonsils, restore it to its glass tube, smearing it over the surface of some solidified blood-serum placed at the bottom of the tube, close the tube and send it to the nearest laboratory. The culture is put into an incubator at body heat, the germs sown upon the surface of the [Pg 234] blood-serum grow and multiply, and in twelve hours a positive diagnosis can be made by examining this growth with a microscope. ”

“ With dilution of 1:10, count 10 such fields, and add two ciphers. Thus, with 1:10 dilution, if 150 leukocytes were counted in 10 fields, the leukocyte count would be 15,000 per c.mm. To compensate for possible unevenness of distribution, it is best to count a row of fields horizontally and a row vertically across the disc. This method is applicable to any degree of dilution of the blood, and is simple to remember: one always counts a number of fields equal to the number of times the blood has been diluted, and adds two ciphers. ”

“ This simple method holds good for all counts of 1,000,000 or more. Thus, a count of 2,500,000 is 50 per cent. of the normal. If, then, the hemoglobin has been estimated at 40 per cent., divide 40 (the percentage of hemoglobin) by 50 (the percentage of corpuscles) . This gives 4/5, or 0.8, as the color index.
IV. ENUMERATION OF LEUKOCYTES
The normal number of leukocytes varies from 5000 to 10,000 per cubic millimeter of blood. The number is larger in robust individuals than in poorly nourished ones, and if disease be excluded, may be taken as an index of the individual's nutrition. ”

“ Examine with a low power to see that the cells are evenly distributed. Count with the two-thirds objective and a high eye-piece, or with the long-focus one-sixth and a low eye-piece. [p. 164] A one-fourth objective will be found very satisfactory for this purpose.
With the ordinary ruling of the disc, count all the leukocytes in the large square, multiply by 10 to find the number in 1 c.mm. of diluted blood, and by the dilution to find the number per c.mm. of undiluted blood. In every case at least 100 leukocytes must be counted as a basis for calculation, and it is much better to count 500. ”

“ It is a rare condition, and must be distinguished from hematuria, or blood in the urine, which is common. In both conditions chemic tests will show hemoglobin, but in the latter the microscope will reveal the presence of red corpuscles. Urines which contain notable amounts of hemoglobin have a reddish or brown color, and may deposit a sediment of brown, granular pigment.
Hemoglobinuria occurs when there is such extensive destruction of red blood-cells within the body that the liver cannot transform all the hemoglobin set free into bile-pigment. ”

“ However, when we come to the blood of persons suffering from disease, there are changes in the diameter and even the form of the corpuscles which much complicate the matter; while, in blood-stains of any age, the blood-corpuscles, even with the most artfully-contrived solvent, are so distorted in shape that he would be a bold man who should venture on any definite conclusion as to whether the blood was certainly human, more especially if he had to give evidence in a criminal case. ”

“ The blood is collected in a glass or plastic graduated container and stored under refrigeration. The study of blood donors has, incidentally, given insights into the physiology of bloodletting since the volume customarily removed from a donor is about the same in volume as that taken by a bleeder (one pint or 500 cc) . [86]
The annual physical examination today includes taking a small amount of blood from the finger or a vein in the elbow. This blood is then analyzed for the presence of biochemical components of such diseases as diabetes, anemia, arteriosclerosis, etc. ”