Perianal Tuberculosis

Abstract

The association of tuberculosis (TB) with anal fistulas and abscesses is not uncommon, especially in TB endemic regions. TB can afflict 0.3-16% cases of anal fistulas in endemic areas. The significance of the association of TB with anal fistulas is that if the TB infection is not detected and treated timely, it would lead to non-healing or recurrence of the fistula. Despite several tests in vogue (acid-fast bacilli smear, histopathology, culture, GeneXpert, polymerase chain reaction etc.), there is no gold-standard test that can detect TB with reasonably high sensitivity and specificity. TB culture has high specificity but its sensitivity is low and it takes a long time (6 weeks to 6 months). The other commonly done test is histopathology (HPE) but the latest data has demonstrated that polymerase chain reaction (PCR) is significantly more sensitive than HPE as well as GeneXpert to detect TB. As PCR can detect both live and dead bacilli, it is recommended that a positive PCR test should be correlated with the clinical picture before initiating anti-TB treatment. It has been highlighted that TB may not always be detected in the first sample. Therefore, repeated samples may be required to detect TB especially in patients with high levels of suspicion. The chances of fistula healing are highest when anti-TB therapy is started within 6 weeks of fistula surgery. TB fistulas are much more complex than non-TB fistulas. However, with timely detection and treatment, a high cure rate can be achieved in TB fistulas.