The effect of warming specimens of rapid urease test on its diagnostic accuracy

Resumen

Introduction: Helicobacter pylori (H. pylori) is a prevalentcause of dyspepsia, peptic ulcer and gastric cancer in developingcountries. Among various diagnostic methods,rapid urease test (RUT) is the ideal test for its diagnosisin patients undergoing endoscopy. Studies have identifiedthe factors causing false negative and positive results.One of these factors is proposed to be the temperature ofkeeping specimens, but the results have been controversial.We aimed to compare the diagnostic accuracy of RUTspecimens warmed at 37oC or kept at room temperature(22-25oC) in different time intervals until 24 hours.Methods: 100 patients with dyspepsia who were indicatedfor endoscopic examination were selected based onconvenience sampling method from patients referring toEndoscopy center of Hajar Hospital during August-September2006. After recording the demographic and medicalhistory of patients, three biopsy specimens were takenfrom one portion of the antrum; the first two sampleswere placed in home-made RUT solution and the third biopsywas placed in formalin solution; one tube was placedin incubator with 37oC and the other at room temperature(22-25oC). Positivity of RUT test at different times wascompared to histopathological examination.Results: Infection with Helicobacter pylori was confirmedby histological examination in 66% of patients. After 24hours, sensitivity of incubated RUT was 71% at 37oC, and68% at room temperature (P=0.85). Specificity at 37oCwas 59% and at room temperature was 76% (P=0.19).Median time to positive tests was 2 hours at 37oC and 3hours at room temperature, while RUT became positivefaster at 37oC (P=0.553).Conclusion: The non-significant difference betweengroups revealed that warming could not improve thediagnostic accuracy of RUT test, thus, the standard RUTmethod is recommended.