title: Accuracy of diagnostic tests to detect asymptomatic bacteriuria during pregnancy.
abstract: OBJECTIVE
  A dipslide is a plastic paddle coated with agar that is attached to a plastic cap that screws onto a sterile plastic vial. Our objective was to estimate the diagnostic accuracy of the dipslide culture technique to detect asymptomatic bacteriuria during pregnancy and to evaluate the accuracy of nitrate and leucocyte esterase dipslides for screening.
  
  
  METHODS
  This was an ancillary study within a trial comparing single-day with 7-day therapy in treating asymptomatic bacteriuria. Clean-catch midstream samples were collected from pregnant women seeking routine care. Positive and negative likelihood ratios and sensitivity and specificity for the culture-based dipslide to detect and chemical dipsticks (nitrites, leukocyte esterase, or both) to screen were estimated using traditional urine culture as the "gold standard."
  
  
  RESULTS
  : A total of 3,048 eligible pregnant women were screened. The prevalence of asymptomatic bacteriuria was 15%, with Escherichia coli the most prevalent organism. The likelihood ratio for detecting asymptomatic bacteriuria with a positive dipslide test was 225 (95% confidence interval [CI] 113-449), increasing the probability of asymptomatic bacteriuria to 98%; the likelihood ratio for a negative dipslide test was 0.02 (95% CI 0.01-0.05), reducing the probability of bacteriuria to less than 1%. The positive likelihood ratio of leukocyte esterase and nitrite dipsticks (when both or either one was positive) was 6.95 (95% CI 5.80-8.33), increasing the probability of bacteriuria to only 54%; the negative likelihood ratio was 0.50 (95% CI 0.45-0.57), reducing the probability to 8%.
  
  
  CONCLUSIONS
  A pregnant woman with a positive dipslide test is very likely to have a definitive diagnosis of asymptomatic bacteriuria, whereas a negative result effectively rules out the presence of bacteriuria. Dipsticks that measure nitrites and leukocyte esterase have low sensitivity for use in screening for asymptomatic bacteriuria during gestation.
  
  
  BACKGROUND
  ISRCTN, isrctn.org, 1196608
  
  
  METHODS
  II.
authors.affiliation: Centro Rosarino de Estudios Perinatales, Santa Fe, Argentina. lmignini@crep.com.ar
authors.forename: Luciano
authors.initials: L
authors.lastname: Mignini
authors.forename: Guillermo
authors.initials: G
authors.lastname: Carroli
authors.forename: Edgardo
authors.initials: E
authors.lastname: Abalos
authors.forename: Mariana
authors.initials: M
authors.lastname: Widmer
authors.forename: Susana
authors.initials: S
authors.lastname: Amigot
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: Nardin
authors.forename: Daniel
authors.initials: D
authors.lastname: Giordano
authors.forename: Mario
authors.initials: M
authors.lastname: Merialdi
authors.forename: Graciela
authors.initials: G
authors.lastname: Arciero
authors.forename: Maria
authors.initials: M
authors.lastname: Del Carmen Hourquescos
mesh_terms: D001437:Bacteriuria / Q000175:diagnosis*; D002265:Carboxylic Ester Hydrolases / Q000652:urine; D015169:Colony Count, Microbial; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D009573:Nitrites / Q000652:urine; D011237:Predictive Value of Tests; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis*; D011933:Reagent Kits, Diagnostic; D016482:Urinalysis; D014944:World Health Organization
chemical_list: D009573:Nitrites; D011933:Reagent Kits, Diagnostic; C021443:leukocyte esterase; D002265:Carboxylic Ester Hydrolases