<prompt> Most sensitive non invasive test for diagnosis of H pylori?Rapid urease testDemonstration of organism in gastric biopsyBreath urea testELISA  <response>: ELISA test has sensitivity of 80 and has been replaced by C-13 urea breath test and fecal antigen immunoassay. Both have sensitivity of 90. Hence though rapid urease test is having a comparable sensitivity and higher specificity, it is an invasive test. Sensitivity of various diagnosis tests Test Sensitivity in Rapid urease INVASIVE 80-95 Histology 80-90 Serology 80 Urea breath test NON INVASIVE 90 Stool antigen 90 In assessment of response to treatment, non-invasive tests are preferred. Breath urea test will be done but can be false negative if done within 4 weeks of antibiotic treatment. High levels of interleukin 1,2,6 8 and TNFa,IFN gamma in the gastric epithelium are found. 