Evaluation of histology as a Helicobacter pylori detection method and analysis of associated problems

Helicobacter pylori is regarded as a common cause of gastritis and peptic ulcer disease. The most commonly used H. pylori detection method in Sri Lanka is histology. However, the detection rate of H. pylori in routine histology practice is low. Therefore, we conducted the following study to evaluate the diagnostic efficacy of histology and to analyze the possible problems associated with H. pylori detection. Multiple endoscopic gastric biopsies were obtained from a sample of 205 patients detected to have endoscopic gastric erythema or ulcers. Biopsies were formalin fixed and paraffin embedded and stained with haematoxylin and eosin, toluidine blue and immunohistochemistry. Serum was collected for screening of anti H. pylori antibodies using an immunochromatography based kit method. Diagnostic efficacy of histology was evaluated against immunohistochemistry as the gold standard. Inter observer variation among four pathologists was assessed using the intraclass correlation coefficient. Haematoxylin and eosin showed a sensitivity of 100% and specificity of 99% and toluidine blue had 100% sensitivity and 98.5% specificity. Average measures of intra class correlation coefficient for H&E was 0.428 (95% CI 0.228 – 0.588) and for toluidine blue stain 0.320 (95% CI 0.085 0.513). The sero prevalence of anti – H. pylori antibodies was 4.9%. In conclusion, sensitivity, specificity and negative predictive values of histology in detecting H. pylori are shown to be high. Main limitations were, low positive predictive value and unsatisfactory interobserver agreement. Sampling errors and exposure to antibiotics appeared to be an unlikely cause of the low detection rate with histology.