Question

What is the approximate pH of amniotic fluid?

• A. 6.7-6.9
• B. 6.9-7.0
• C. 7.1-7.2
• D. 7.4-7.5

Hint:

Amniotic fluid is mildly alkaline, about 7.2, which is why it turns nitrazine paper blue.

Answer 1

The Correct Option is C

Step 1: Recall why fluid pH matters in pregnancy.
Doctors need a quick way to tell if a leaking fluid is amniotic fluid or just vaginal discharge, and pH is the key difference between the two.

Step 2: Compare the two fluids.
Vaginal secretions are acidic, roughly pH 3.8 to 4.5, kept that way by normal vaginal flora. Amniotic fluid, on the other hand, is close to neutral but tilted slightly alkaline, at about pH 7.2.

Step 3: Use this to read the nitrazine test.
Nitrazine paper turns blue in an alkaline fluid and stays yellow in an acidic one. Since amniotic fluid sits around 7.2, well above 6.5, it turns the paper blue, which is how the test flags a ruptured membrane.

Step 4: Pick the closest range.
Out of the ranges offered, 7.1 to 7.2 is the one that lines up with the accepted value of about 7.2, while the other ranges sit too low or slightly too high.
\[ \boxed{7.1-7.2} \]