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FALLACIES OF ROUTINE BLOOD COUNT:AUTOMATED CELL ANALYSERVERSUS MANUAL METHOD
OP KAPOOR
Ex. Hon. Physician, Jaslok Hospital and Bombay Hospital, Mumbai, Ex. Hon. Prof. of Medicine, Grant Medical College and JJ Hospital, Mumbai 400 008.
Many laboratories have started doing routine blood count by automated cell analyser and call it a ‘histogram’ (the graphs drawn by the computer) and present it to the doctors. Such reports not only cost more money, but also are not really required by an average patient. The following are the spurious results, which are often obtained from the reports of such automated analysers:-
1.Quite often low or high Hb reports are given
2.Often ‘high’ WBC count is reported wrongly
3.Often, the report of diminished platelets is wrong. If done by manual method, it is normal.
However, these minor mistakes can occur even in ordinary laboratories, which are not using automated machines. What is more important, which I have observed in my practice, is that patients of leukaemia can be easily missed. In the last three years, I have picked up three patients of leukaemia, who were missed by histogram. Similarly, the abnormal monocyte cells of infectious mononucleosis, which are really speaking more helpful in the diagnosis than Paul Bunnel test or recent ‘spot’ test, are often missed by this method.
Really speaking, these machines have been brought in the five star hospitals and big laboratories, to reduce the load on software and manpower. Good lab technicians are difficult to find, and thus the pathologists are dependent on the sophisticated machines, which if not calibrated every morning, can give wrong results. Lucky are the doctors like me, who have a morphologist as a technician and who, from a finger prick smear, can help in diagnosing :
1.Low RBC count (anaemia)
2.Shape of RBC (e.g. microcytosis) - Type of anaemia.
3.Iron content of RBCs (hypochromia)
4.Platelet count and WBC count
5.Also differential count
6.Can spot abnormal monocytes
7.Can spot malarial parasites (and more important, the type of malaria - whether falciparum or vivax, as the treatment differs in each case)
8.Can spot abnormal cells of leukaemia, which is a silent disease to start with.
The last patient I saw, was from Aurangabad and was seen at more than three centres at Aurangabad and Bombay, and had three histogram reports. This patient was a diagnostic problem for so-called kidney or a cardiac oedema. On examination, I found signs of frank hypothyroidism, but my enthusiasm to treat this patient waned when my technician showed some abnormal cells which he could not identify.
In my laboratory, my dictum is that any cell which looks to me abnormal, is likely to be a leukaemic cell and this patient, who had absolutely no signs of acute leukaemia and had total WBC count of 15-16,000 in different laboratories, was confirmed by a senior haematologist to be suffering from leukaemia and was sent abroad immediately for latest therapeutic modalities available in the form of marrow or stem cell transplant.
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