Prospective Study to Evaluate the Number and the Location of Biopsies in Rapid Urease Test for Diagnosis of Helicobacter Pylori

Helicobacter pylori (H. pylori) can cause a wide variety of illnesses such as peptic ulcer disease, gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. The diagnosis and eradication of H. pylori are crucial. The diagnosis of H. pylori is usually based on the rapid urease test (RUT) and gastric antral biopsy for histology. The aim of this study is to evaluate the numbers of needed biopsies and their location (antrum/fundus) to obtain optimal result for the diagnosis of H. pylori. Three hundred fifty consecutive patients were recruited, 210 fulfill the inclusion criteria and had nine gastric biopsies for the detection of H. pylori infection: two antral for the first RUT (RUT1), one antral and one fundic for the second (RUT2), one antral for the third (RUT3) and two antral with two fundic for histology (HES, Giemsa, PAS). The reading of the 3 types of RUT was performed at 1 hour, 3 hours and 24 hours and biopsies were read by two experienced pathologists not informed about the result of RUT. Results of RUT were considered positive if H. pylori was found on histology of at least one biopsy. The RUT1 at 1h, 3h and 24h has a sensitivity of 72%, 82% and 89% and a specificity of 100%, 99% and 87% respectively. The positive predictive value (PPV) was 100%, 99% and 85% respectively and the negative predictive value (NPV) of 81%, 87% and 90%. The RUT2 at 1h, 3h and 24h, respectively, had a sensitivity of 86%, 87% and 91% and a specificity of 99%, 97% and 90%. The PPV was 99%, 96% and 88% and NPV of 89%, 90%, 94%. The RUT3 at 1h, 3h and 24h, respectively, had a sensitivity of 70%, 74% and 84% and a specificity of 99%, 99% and 94%. The PPV was 99%, 99% and 92% and NPV of 79%, 81% and 87%. The best sensitivity and specificity were obtained for RUT1 read at 3h, for RUT2 read 1h and 3h, and the RUT3 read at 24h.This study demonstrates that the best sensitivity and specificity of rapid test for urease is obtained when fundic plus antral biopsy specimens are used with a reading time at 3 hours.