Genital tuberculosis: Comparative study of the diagnostic modalities

Genital tuberculosis (GTB) is one of the major causes for severe tubal disease leading to infertility. Unlike pulmonary tuberculosis (TB), the clinical diagnosis of GTB is difficult because in the majority of cases the disease is either asymptomatic or has varied clinical presentation. Routine laboratory tests are of little value in the diagnosis. The objective of this study was to compare the modalities of polymerase chain reaction (PCR) technique, acid fast bacilli (AFB) culture and AFB staining.

The women visiting in vitro fertility center during December 2012 and May 2013 were included in this study. A total of 227 aseptically collected endometrial tissue samples were processed. AFB staining, AFB culture and PCR were carried out using standard procedures.

Out of 227 patients suspected of GTB, 133 were found to be positive either by AFB smear microscopy, culture or PCR. Out of 133 samples, two samples (1.5%) were found to be positive by all three methods, i.e. microscopy, culture and PCR, 11 (4.8%) were found to be positive by both PCR and culture, whereas 126 (86%) samples were found to be positive only by PCR. The PCR has failed to detect seven cases that were positive by conventional culture method.

Our study showed that the conventional methods of diagnosis like microscopy and culture are less sensitive when compared with PCR. PCR also helped in early diagnosis of infection. However simultaneously, false negative results were an important limitation of this method. PCR negative samples were found to be positive by culture methods. Deoxyribose nucleic acid PCR is not reliable for TB due to false positive or negative result. Thus, we suggest both culture and PCR as important diagnostic methods for detection of GTB.