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.

Table 2 Detection time of tuberculosis in patients who underwent surgery for anal fistula

Detection of TB	Total patients operated for anal fistula (n = 113)
After first surgery	89/113 (78.8%)
Repeat samples in patients with high level of suspicion1	18/113 (15.9%)
Samples in patients with Recurrence of fistula	6/113 (5.3%)

¹Non-healing of fistula, occurrence of new abscesses during treatment or delayed recurrences (fistula recurring 3-6 mo after complete healing). Tuberculosis detected in out-patient department (Patients not operated): 9. TB: Tuberculosis.

Table 3 Patient Demographics and fistula characteristics

Total patients operated = 740	Non-TB fistula (n = 627)	TB fistula (n = 113)	P value
Sex (M/F)	545/82	99/14	0.68
Age ± 2SD (yr)	38.6 ± 11.3	39.4 ± 11.2	0.17
Follow-up: Median (Range) (mo)	27 (2-75)	34 (2-74)	0.23
Multiple tracts, n (%)	408 (65.1)	86 (76.1)	0.022a
Associated abscess, n (%)	164 (26.2)	55 (48.7)	< 0.00001a
Horseshoe tract, n (%)	133 (21.2)	38 (33.6)	0.0052a
Supralevator tract, n (%))	94 (15.0)	21 (18.6)	0.32b
Recurrent fistula, n (%)	328 (52.3)	74 (65.5)	0.0103a
Fistula grading (SJUH Classification) Grade, n (%)	I- 85 (13.6)	I-7 (6.2)	0.0038a
	II-96 (15.3)	II-11 (9.7)
	III-71 (11.3)	III- 4 (3.5)
	IV-281 (44.8)	IV-70 (61.9)
	V-94 (15.0)	V-21 (18.6)
Fistula healing-after first surgery	499/5561 (89.7)	78/1022 (76.5)	0.0005a
Reoperations (healed)	25 (19)	16 (12)	0.0001a
Fistula healing-overall	518/5561 (93.2)	90/1022 (88.2)	0.101b

¹71 patients had short follow-up or lost to follow-up.

²11 patients had short follow-up or lost to follow-up.

^aSignificant.

^bNot-significant. TB: Tuberculosis; SJUH: St James University Hospital.

Table 4 Proportion of complex and simple fistulas in non-tuberculosis and tuberculosis fistula groups, n (%)

Total patients operated = 740	Simple fistulas (fistulotomy possible)	Complex fistulas (fistulotomy not possible)	Significance (Fisher’s exact test)
Non-TB Fistula (n = 627)	349 (55.7)	278 (44.3)	P < 0.00001 (Significant)
TB Fistula (n = 113)	35 (31)	78 (69)

Pus sample collected in surgeon’s office (Patient not investigated and not operated upon, lost to follow-up) = 36. Tuberculosis positive in 9 /36 of these patients; TB: Tuberculosis.