Joint infection: synovial fluid analysis: practice question

A Orthopaedics 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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Orthopaedics · Joint infection: synovial fluid analysis

Sample item

Which synovial fluid finding best supports septic arthritis?

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

The answer and the reasoning

D. Purulent fluid with a leucocyte count above 50,000 per cubic mm, mostly neutrophils

Septic joint fluid is turbid or purulent with a high neutrophil count, usually over 50,000 per cubic mm, low glucose and positive Gram stain or culture. Crystal analysis excludes concomitant gout but does not exclude infection.

Option by option

  • A. Rhomboid positively birefringent crystals

    Positively birefringent rhomboid crystals indicate pseudogout.

  • B. Rice bodies with lymphocytes

    Rice bodies suggest chronic tuberculous or rheumatoid synovitis.

  • C. Clear viscous fluid with 500 cells per cubic mm

    A low count in clear fluid suggests a non-inflammatory effusion.

  • D. Purulent fluid with a leucocyte count above 50,000 per cubic mm, mostly neutrophils (correct)

    Correct. A high neutrophil count with purulence is characteristic.

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.

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Questions about this Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is D, Purulent fluid with a leucocyte count above 50,000 per cubic mm, mostly neutrophils. Septic joint fluid is turbid or purulent with a high neutrophil count, usually over 50,000 per cubic mm, low glucose and positive Gram stain or culture.

Why is "Rhomboid positively birefringent crystals" not the answer?

Positively birefringent rhomboid crystals indicate pseudogout.

Why is "Rice bodies with lymphocytes" not the answer?

Rice bodies suggest chronic tuberculous or rheumatoid synovitis.

Why is "Clear viscous fluid with 500 cells per cubic mm" not the answer?

A low count in clear fluid suggests a non-inflammatory effusion.

What concept does this question test?

It tests Joint infection: synovial fluid analysis in Orthopaedics. Crystal analysis excludes concomitant gout but does not exclude infection.

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 Joint infection: synovial fluid analysis?

Pair each fracture with its classic complication and nerve injured. Then use the flashcards and the other Orthopaedics 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.