2. Cases in which the clinical history and physical signs make the diagnosis certain (presence of tubercle bacilli in the sputum render, of course, any other test unnecessary).
3. Cases of recent haemoptysis.
4. Grave conditions, as severe heart disease, nephritis, marked arteriosclerosis, etc.
5. Convalescence from acute infectious diseases, typhoid fever, pneumonia, etc.
13. Interpretation of the Positive Subcutaneous Tuberculin Reaction:
Occurrence of reaction, following the subcutaneous tuberculin test, signifies the existence of infection; it does not signify that the individual is clinically tuberculous. To quote E. R. Baldwin, of Saranac Lake: "The tuberculin test is of very limited value in determining tuberculous disease; it is of extreme value in detecting tuberculous infection."
The test results in positive reaction in cases with latent as well as active processes.
The decision as to the patient being clinically tuberculous (ill with tuberculosis) must rest on the consideration of the clinical history and the results of the physical examination.
It is maintained by some that the subcutaneous tuberculin reaction is more rapid in onset and more marked in degree in cases of recent infection. On the other hand, the test is negative in a certain proportion of far advanced cases.