Dear Editor:

The recent publication by Garg entitled “Comparison of histopathology and real-time polymerase chain reaction (RT-PCR) for detection of Mycobacterium tuberculosis in fistula-in-ano (Int J Colorectal Dis. 2017 Feb 16. doi: 10.1007/s00384-017-2783-y. [Epub ahead of print])” is very interesting [1]. Garg noted that “Polymerase chain reaction was significantly more sensitive than histopathology in detecting tuberculosis in fistula-in-ano. Histopathology might be missing out tuberculosis in many patients leading to recurrence of the fistula.” Indeed, it is no doubt that the PCR will have a better diagnostic sensitivity. Nevertheless, there are also many other facts to be considered. First, the PCR technique is more expensive and might not be available in some settings. Second, the diagnostic property of any diagnostic test also depends on the quality control of the test. The error in specimen collection, which is the pre-analytical error, is extremely common in any laboratories whether it is accredited and certified or not [2].