title: Diagnosis of subclinical amniotic fluid infection prior to rescue cerclage using gram stain and glucose tests: an individual patient meta-analysis.
abstract: OBJECTIVE
  Microbial invasion of the amniotic cavity (MIAC) can affect outcomes following rescue cerclage. We carried out a study to compare the diagnostic performance of the Gram stain and glucose tests for detecting subclinical MIAC.
  
  
  METHODS
  We used individual-level data from published studies on Gram stain, glucose, and amniotic fluid culture among women with preterm labour. We calculated the sensitivity, specificity, area under the curve (AUC) and other indices, with amniotic fluid culture results used as the gold standard. The probability of infection using both tests as predictors was also estimated using logistic regression.
  
  
  RESULTS
  The rate of culture-confirmed MIAC was 11.8% (34 of 288 women). The Gram stain test yielded a sensitivity of 65% (95% CI 46% to 78%) and a specificity of 99% (95% CI 98% to 100%). A positive Gram stain or glucose test had a sensitivity of 88% (95% CI 72% to 96%) and a specificity of 87% (95% CI 82% to 90%), while a positive Gram stain and a positive glucose test had a sensitivity of 62% (95% CI 44% to 77%) and a specificity of 100% (95% CI 98% to 100%). The AUC for the tests were Gram stain 0.82 (95% CI 0.74 to 0.90), glucose 0.86 (95% CI 0.80 to 0.93), and combined Gram stain and glucose 0.92 (95% CI 0.86 to 0.98). Using the tests, singly or in combination, provided greater clinically important calibration, risk-stratification, and classification accuracy than using no tests.
  
  
  CONCLUSIONS
  Amniotic fluid Gram stain and/or glucose testing provides substantially improved performance for the diagnosis of subclinical MIAC compared with no testing.
authors: Department of Obstetrics and Gynaecology, University of British Columbia, and the Children's and Women's Hospital and Health Centre of British Columbia, Vancouver BC.
authors: Sarka
authors: S
authors: Lisonkova
authors: Department of Obstetrics and Gynaecology, University of British Columbia, and the Children's and Women's Hospital and Health Centre of British Columbia, Vancouver BC; Department of Obstetrics and Gynaecology, College of Medicine, King Saud University, Riyadh, Saudi Arabia; School of Population and Public Health, University of British Columbia, Vancouver BC.
authors: Yasser
authors: Y
authors: Sabr
authors: Department of Obstetrics and Gynaecology, University of British Columbia, and the Children's and Women's Hospital and Health Centre of British Columbia, Vancouver BC; School of Population and Public Health, University of British Columbia, Vancouver BC.
authors: K S
authors: KS
authors: Joseph
mesh_terms: D000649:Amniocentesis; D000653:Amniotic Fluid / Q000737:chemistry* / Q000382:microbiology*; D023802:Cerclage, Cervical; D002821:Chorioamnionitis / Q000175:diagnosis / Q000382:microbiology; D005260:Female; D005840:Gentian Violet; D005947:Glucose / Q000032:analysis*; D006801:Humans; D007239:Infections / Q000175:diagnosis* / Q000382:microbiology; D010619:Phenazines; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis* / Q000382:microbiology; D011262:Pregnancy Trimester, Second; D012680:Sensitivity and Specificity
chemical_list: C035863:Gram's stain; D010619:Phenazines; D005947:Glucose; D005840:Gentian Violet
keywords: cervical insufficiency; glucose concentration test; gram stain test; microbial invasion of amniotic cavity