Diagnosis of anorectal tuberculosis by polymerase chain reaction, GeneXpert and histopathology in 1336 samples in 776 anal fistula patients

Table 1 Outcome of tested samples (tissue and pus) tested

Samples	PCR-Pus (Total No./positive for TB)	PCR-Tissue (Total No. /positive for TB)	HPE (Total No./positive for TB)	GeneXpert (Total No./positive for TB)
First surgery	206/49	673/47	184/3	102/1
Repeat samples in patients with high level of suspicion1	55/17	9/1	0	0
Samples in patients with recurrence of fistula	34/2	21/4	13/0	3/0
Out-patient department (Patients not operated)	36/9	0	0	0
TOTAL/ Positive for TB 1336/133 (9.95%)	331/77 (23.2%)	703/52 (7.4%)	197/3 (1.5%)	105/1 (0.9%)
Test of significance	PCR-Pus (23.2%) vs PCR-Tissue (7.4%) P < 0.00001 (Fisher’s exact test)
	PCR-Tissue (7.4%) vs HPE (1.5%) P = 0.0012 (Fisher’s exact test)
	PCR-Pus (23.2%) vs PCR-Tissue (7.4%) vs HPE (1.5%) P < 0.00001 (Chi square test)

¹Non-healing of fistula, occurrence of new abscesses during treatment or delayed recurrences (fistula recurring 3-6 mo after complete healing). TB: Tuberculosis; PCR: Polymerase chain reaction; HPE: Histopathology.