Vaginal Fluid pH

Aka: Vaginal Fluid pH, Nitrazine Paper, Nitrazine

II. Indications

  1. Evaluation for Premature Rupture of Membranes

III. Mechanism

  1. Nitrazine Paper relies on Prussian blue reaction
  2. Requires alkaline paper to cause reaction

IV. Technique

  1. Obtain fluid for exam (usually after Vaginal Pooling)
  2. Place Nitrazine Paper in fluid
    1. Paper turns bright blue in alkaline fluid

V. 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)

VI. 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)

VII. Efficacy

  1. Test Sensitivity: 90-97%
  2. Test Specificity: 70% (as low as 16% in some studies)

VIII. .

IX. References

  1. Bennett (1993) Am J Perinatol 10(2):101-4 [PubMed]

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Related Studies

Ontology: Nitrazine yellow (C0068806)

Concepts Indicator, Reagent, or Diagnostic Aid (T130) , Organic Chemical (T109)
MSH C013617
SnomedCT 86750008
English 2-((2,4-dinitrophenyl)azo)-1-naphthol 3,6-disulfonic acid, 3,6-naphthalenedisulfonic acid, 2-((2,4-dinitrophenyl)azo)-1-hydroxy, 3-((2,4-dinitrophenyl)azo)-4-hydroxy-2,7- naphthalenedisulfonic acid, DNPNS, nitrazine paper, nitrazine yellow, phenaphthazine, Phenaphthazine, PHENAPHTHAZINE, Nitrazol yellow, Nitrazine yellow stain (substance), Nitrazine yellow stain, Nitrazine yellow, Nitrazine yellow (substance), Nitrazine Paper
Spanish amarillo de nitrazina (sustancia), amarillo de nitrazina, colorante amarillo de nitrazina (sustancia), colorante amarillo de nitrazina
Derived from the NIH UMLS (Unified Medical Language System)

Related Topics in Pathology and Laboratory Medicine

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