At 36 weeks of pregnancy, a woman presents for an antenatal visit with suspected rupture of membranes. A Nitrazine paper test is conducted to differentiate amniotic fluid from normal vaginal secretions. Which statement correctly describes the physiological basis of this test?

1. A

   Amniotic fluid contains more nutrients and electrolytes than vaginal fluid

2. B

   Amniotic fluid has a higher pH, whereas vaginal secretions have a lower pH

3. C

   Amniotic fluid is always thick and yellow in appearance

4. D

   Amniotic fluid has fewer electrolytes than vaginal secretions

Appeared in: NORCET-11 Prelims

Explanation

• Nitrazine paper detects pH difference between fluids.
• Amniotic fluid is alkaline (pH above 7.0), vaginal secretions are acidic (pH 4.5-5.5).
• The test is positive (blue color) when pH is higher, indicating amniotic fluid.

Why Other Options Were Wrong

• Option A: Nutrient and electrolyte content is not the basis for the Nitrazine test; the test detects pH, not composition.
• Option C: Amniotic fluid is usually clear or pale straw-colored, not thick and yellow; appearance is not used for this test.
• Option D: Electrolyte concentration is not the physiological basis for the Nitrazine test.

Related Visual

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiological basis of the Nitrazine paper test for rupture of membranes as background academic context rather than a clinical decision trigger.
• Nurses use the Nitrazine test to quickly identify ruptured membranes and prevent complications like infection or cord prolapse.
• What if? If the test is falsely positive due to blood or semen, further confirmation with the fern test or clinical assessment is needed.

How to Approach the Question

• Read the clinical scenario and identify the test being discussed.
• Recall the principle behind the Nitrazine paper test (pH detection).
• Eliminate options that do not relate to pH or that describe unrelated properties.
• Choose the answer that directly explains the physiological basis for the test.

Concept Tested & Keywords

• Concept Tested: Physiological basis of the Nitrazine paper test for rupture of membranes
• Stem keywords: 36 weeks pregnancy, antenatal visit, suspected rupture of membranes, Nitrazine paper test, amniotic fluid, vaginal secretions
• Lead-in keywords: correctly describes, physiological basis
• Clinical cues: Suspected rupture of membranes at term requires prompt diagnosis to prevent complications.

Question ID

Q6XelrQ-HkB6Nmri9H9TyN

Copy ID

Reference Book

E6 Obstetrics Williams p. 23-42