Abstract:

Objective: To investigate the diagnostic value of T cell spot test (T-SPOT. TB) with different thresholds in tuberculosis peritonitis. Methods: From January 2016 to December 2020, 48 patients with abdominal effusion diagnosed in Shaanxi Provincial Hospital of Tuberculosis Prevention and treatment were selected as the research objects. All patients underwent intraperitoneocentesis and peritoneal tissue biopsy under ultrasound guidance. At the same time, peripheral blood T-SPOT.TB, abdominal fluid effusion T-SPOT.TB, peritoneal fluid effusion Mycobacterium tuberculosis smear, peritoneal fluid effusion BACTEC MGIT 960 fluid culture (MGIT 960 liquid culture), peritoneal fluid molecular biology examination, peritoneal histopathological examination and molecular biology examination were performed. Final clinical composite criteria were used as a reference. The sensitivity, specificity, compliance rate and consistency of peripheral blood T-SPOT.TB and abdominal effusion T-SPOT.TB (setting 6 SFC/10⁶ and 30 SFC/10⁶, respectively) were evaluated in tuberculous peritonitis. Results: Of the 48 patients, 31 were definitely diagnosed as tuberculous peritonitis, 3 were confirmed by positive antiacid staining of abdominal effusion, 11 were confirmed by positive MGIT 960 liquid culture medium, 13 were confirmed by positive molecular biological tests of peritoneal effusion or peritoneal tissue, 2 were confirmed as granuloma of peritoneal tissue with caseous necrosis, 2 were confirmed as granulomatous inflammation of peritoneal tissue after effective anti-tuberculosis therapy for 2 months. 17 were definitely diagnosed as non-tuberculous peritonitis, with 13 malignant ascites, 2 bacterial ascites, 1 lupus erythematosus, 1 lymphoma lymphoma. Four were diagnosed by pathology ascites, athological diagnosis, 11 by peritoneal histopathology, and 2 by bacterial culture of ascites. Clinical composite standard was used as the reference standard. We choose 6 SFC/10⁶ for peripheral blood T-SPOT.TB, and 30 SFC/10⁶ for peritoneal effusion T-SPOT.TB as positive thresholds, respectively. The sensitivity of the three assays tested in tuberculous peritonitis were 83.9% (95%CI:65.5%-93.9%), 87.1% (95%CI:69.2%-95.8%) and 83.9% (95%CI:65.5%-93.9%), and the specificity were 76.5% (95%CI:48.8%-92.2%), 82.4% (95%CI:55.8%-95.3%) and 94.1% (95%CI:69.2%-99.7%), with the conformance rate of 81.2% (95%CI:68.7%-92.1%), 85.4% (95%CI:66.8%-97.2%) and 87.5%(95%CI:72.1%-98.4%), and the Kappa values of 0.596, 0.685 and 0.778, respectively. Conclusion: With the clinical composite standard as the reference standard, setting different positive T-SPOT.TB threshold values in abdominal effusion might change the diagnostic efficacy of tuberculosis peritonitis, and raising the positive threshold from 6 SFC/10⁶ to 30 SFC/10⁶ might enhance its diagnostic efficacy.

Key words: Peritonitis, tuberculous, Immunologic tests, Comparative study