Lab

Vaginal Fluid pH

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Vaginal Fluid pH, Nitrazine Paper, Nitrazine

  • Indications
  • Mechanism
  1. Nitrazine Paper relies on Prussian blue reaction
  2. Requires alkaline paper to cause reaction
  • Technique
  1. Obtain fluid for exam (usually after Vaginal Pooling)
  2. Place Nitrazine Paper in fluid
    1. Paper turns bright blue in alkaline fluid
  • Interpretation
  • Nitrazine Paper
  1. Normal Vaginal pH 4.5-6.0
    1. Paper does not change color
  2. Ruptured Vaginal pH 7.1-7.3
    1. Suggests PROM (paper blue)
  • Causes
  • False Positive Nitrazine positive (pH >7)
  1. Blood
  2. Semen
  3. Antiseptic solutions
  4. Urine with increased pH (alkaline urine)
  5. Vaginal infection or Cervicitis (e.g. Bacterial Vaginosis)
  • Efficacy
  1. Test Sensitivity: 90-97%
  2. Test Specificity: 70% (as low as 16% in some studies)