title: Premedication with Xylocaine spray does not lead to a false positive rapid urease test.
abstract: Rapid urease tests are used for quick identification of Helicobacter pylori during upper gastrointestinal endoscopy. Rapid urease test solutions contain urea, which in the presence of H. pylori urease, generates ammonia, which changes the test medium color to indicate a positive result. Theoretically, Xylocaine spray (ASTRA, Södertalje, Sweden), which has a basic pH value, could cause a similar positive reaction in the test medium. To determine whether patients premedicated with Xylocaine spray have a higher rate of false positive urease tests, we compared the results of a rapid urease test and histologic stains in 107 patients, 54 premedicated with Xylocaine spray and 53 premedicated with intravenous midazolam but not Xylocaine spray. There were no significant differences in test sensitivity, specificity, or predictive values between the study groups. We conclude that patients can be premedicated with Xylocaine spray without concern that the false positive rate of rapid urease tests will increase.
authors.affiliation: Department of Gastroenterology, Soroka Medical Center, Beer-Sheva, Israel.
authors.forename: A D
authors.initials: AD
authors.lastname: Sperber
authors.forename: A
authors.initials: A
authors.lastname: Fich
authors.forename: I
authors.initials: I
authors.lastname: Sztarkier
authors.forename: H J
authors.initials: HJ
authors.lastname: Zirkin
authors.forename: P
authors.initials: P
authors.lastname: Krugliak
authors.forename: H S
authors.initials: HS
authors.lastname: Odes
authors.forename: N
authors.initials: N
authors.lastname: Hilzenrat
authors.forename: N
authors.initials: N
authors.lastname: Gaspar
authors.forename: A
authors.initials: A
authors.lastname: Zilberman
mesh_terms: D000779:Anesthetics, Local; D005189:False Positive Reactions; D005260:Female; D016481:Helicobacter Infections / Q000175:diagnosis*; D016480:Helicobacter pylori; D006801:Humans; D006993:Hypnotics and Sedatives / Q000627:therapeutic use; D008012:Lidocaine; D008297:Male; D008874:Midazolam / Q000627:therapeutic use; D008875:Middle Aged; D011237:Predictive Value of Tests; D011292:Premedication; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014510:Urease / Q000032:analysis*
chemical_list: D000779:Anesthetics, Local; D006993:Hypnotics and Sedatives; D008012:Lidocaine; D014510:Urease; D008874:Midazolam