Normal pregnancy: maternal physiology: practice question

A OBG question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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OBG · Normal pregnancy: maternal physiology

Sample item

Which of the following changes occurs in normal pregnancy?

ASerum creatinine rises because of falling GFRBSystemic vascular resistance rises in the second trimesterCTotal leucocyte count falls to below 4000 per cubic mmDPlasma volume increases more than red cell mass, causing physiological haemodilution

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Plasma volume increases more than red cell mass, causing physiological haemodilution

Plasma volume rises by about 40 to 50 per cent while red cell mass rises by about 20 to 30 per cent, so haemoglobin concentration falls. This physiological anaemia is maximal at 32 to 34 weeks. Vascular resistance and creatinine fall.

Option by option

A. Serum creatinine rises because of falling GFR
GFR rises by about 50 per cent, so serum creatinine falls.
B. Systemic vascular resistance rises in the second trimester
Systemic vascular resistance falls because of progesterone-mediated vasodilatation.
C. Total leucocyte count falls to below 4000 per cubic mm
Leucocytosis is normal in pregnancy and labour.
D. Plasma volume increases more than red cell mass, causing physiological haemodilution (correct)
Correct. Disproportionate plasma expansion lowers haematocrit and haemoglobin concentration.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this OBG question

What is the answer to this OBG question?

The best answer is D, Plasma volume increases more than red cell mass, causing physiological haemodilution. Plasma volume rises by about 40 to 50 per cent while red cell mass rises by about 20 to 30 per cent, so haemoglobin concentration falls.

Why is "Serum creatinine rises because of falling GFR" not the answer?

GFR rises by about 50 per cent, so serum creatinine falls.

Why is "Systemic vascular resistance rises in the second trimester" not the answer?

Systemic vascular resistance falls because of progesterone-mediated vasodilatation.

Why is "Total leucocyte count falls to below 4000 per cubic mm" not the answer?

Leucocytosis is normal in pregnancy and labour.

What concept does this question test?

It tests Normal pregnancy: maternal physiology in OBG. This physiological anaemia is maximal at 32 to 34 weeks. Vascular resistance and creatinine fall.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Normal pregnancy: maternal physiology?

Learn management algorithms as steps: PPH, eclampsia, ectopic pregnancy. Then use the flashcards and the other OBG questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.