I seem to be seeing an epidemic of tuberculosis ( TB ) these days ! Practically all Indian patients who come to me have been treated with anti TB drugs ! Most gynecologists now routinely test the
endometrium ( uterine lining) for TB using a new generation of fancy ( and very expensive !) tests such as PCR ( polymerase chain reaction) . In the past, the only test available for making a diagnosis of TB was by growing the TB bacillus in the laboratory; or by finding tubercles on histological examination. However, both these methods are quite insensitive.
This is why PCR was introduced with great hope. This test amplifies a specific segment of DNA and labs believed that finding DNA sequences unique to the tubercle bacillus in the endometrial tissue would help to make a unequivocal diagnosis of TB infection. Unfortunately, this test has proven to be unreliable because it is too sensitive and can pick up even minute quantities of DNA, leading to many false positives. Because it is very expensive, it has not been validated in the fertile population, and in some labs, over 50% of the samples sent to them test positive for PCR for TB ! This obviously means the test is unreliable, but doctors continue doing it, without understanding its limitations and pitfalls – and patients are unnecessarily subjected to the trauma of 9 months of useless treatment !
Here's one simple reason why I feel the test is unreliable. When the tubercle bacillus reaches the genital tract ( from the lungs) , it first attacks the fallopian tubes and then later damages the endometrium . This means that whenever the endometrium is TB PCR positive, tissue from the fallopian tube should also be PCR positive. However, for many patients whose endometrium is positive, the fallopian tube is negative !
The other group of tests which is very popularly misused to make the diagnosis of TB are the blood tests which test for the presence of antiTB antibodies – both IgG and IgM. Firstly, remember that these tests are not picking up the presence of the TB bacillus – they are only testing for the presence of antibodies ( produced by the immune system to protect the body !) against the TB bacillus. As most Indians have been exposed to the TB bacillus, it is hardly surprising that many have the presence of antiTB antibodies, and often test positive. Doctors often believe that this is proof of TB infection, and promptly start treatment ! Similarly, the Mantoux skin test also tests merely for the presence of immunity against TB – and can be similarly misinterpreted.
In summary, the diagnosis of TB of the genital tract remains notoriously difficult to make. Most patients are misdiagnosed as having TB when in fact they don’t, and many are treated for no good rhyme or reason !If your gynecologist diagnoses you as having genital TB based on these unreliable tests, then please do NOT start anti-TB medicines. Please insist on getting a second opinion from a physician, preferably once who is a TB specialist !
The truth is that no one really knows how to interpret these results - but no doctor will admit to this fact. What does a positive test mean ? Nothing ! I am sure if a controlled study is done , a lot of fertile women will also turn out to have positive tests for TB ! ( Actually, this would be an easy study to do ! Fertile women who are scheduled for a laparoscopic tubal ligation could have their endometrial biopsy done at the same time and this could be sent for testing for TB. It is my prediction that over 50% of these samples will turn out to be positive ! I'd love to be proven wrong !)
What's the result of all this testing ? A lot of unnecessary expense; and even worse , this leads to 9 months of unnecessary treatment with toxic drugs with unpleasant side effects. As a result of this waste of time, patients get fed up and frustrated. Sadly, most gynecologists are pretty clueless about what these results means - and it's much easier to "do something" ( prescribe antiTB medicines) rather than explain to the patients that nothing needs to be done !