Case-finding□How to diagnosis smear□negative cases in remote areas
Hidenori MASUYAMA,M.D., Dai-ich Dispensary, JATA
1. Sputum negative pulmonary tuberculosis diagnosis made on clinical and/or X-ray: if possible □this diagnosis should only be made by a doctor.
2. Microscopy of the sputum is for the most reliable method which you can use in most places. Try to have three specimens examined.
If only one is positive and the others negative, it is best to confirm with a further positive (because errors or other can occur).
3. In good programmes, only 5-10 percent of patients usually turn out to have a positive sputum. You must tell all patients with chronic cough, especially those with weight loss and/or productive sputum and/or blood-spitting and/or fever and seating which might be due to tuberculosis. Do this wherever you work: in primary care, clinic, hospital or remote areas. Not to do this is bad medicine.
4. Tuberculosis is difficult to diagnose with certainty on X-ray alone. Never treat such a patient without having examined the sputum. X-ray is expensive and unreliable. Patients are often treated for tuberculosis when they do not have it. The X-ray shadows which strongly suggest tuberculosis are:
a) upper zone patchy or nodular shadows (or one or both sides)
b) cavitation (particularly if more than one cavity)
c) calcified shadows may cause difficulties in diagnosis.
Remember this may not be completely diagnostic.
The correct reading of chest X-ray needs a lot of experience. If you suspect tuberculosis from the X-ray and the sputum is negative, give a non-tuberculosis antibiotic for several days and repeat the X-ray. Shadows of an acute pneumonia will show improvement. It is a major error to diagnose tuberculosis on X-ray and fail to examine the sputum.
5. Tuberculosis skin test is often a less reliable method for diagnosis in developing countries.
6. Culture for TB may later be made available as services develop.
Only use it for patients with X-ray shadows suspicious of tuberculosis. Culture makes a definite diagnosis possible.
7. Guidelines or those whom you suspected have tuberculosis but are sputum negative on smear examination are as follows:
If the patient has chest symptoms typical of tuberculosis, but is sputum-negative×3:
If he or she is severely ill and especially if there are abnormal chest sings, get a chest X-ray if possible and start anti-tuberculosis treatment (Fig. 1).
If he or she is not severely ill, arrange a chest X-ray if possible (Fig 3).
