Identification: Teichmann's test: practice question

A Forensic Medicine 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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Forensic Medicine · Identification: Teichmann's test

Sample item

A suspected dried bloodstain is heated on a slide with a crystal of sodium chloride and glacial acetic acid. Crystals form that are seen under the microscope. Which test is this, and what crystals are seen?

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

The answer and the reasoning

D. Teichmann test; haemin crystals

In Teichmann's test, glacial acetic acid and salt convert haemoglobin to brown rhombic haemin crystals, a confirmatory test for blood. Takayama's test uses pyridine and gives pink feathery haemochromogen crystals. The Florence and Barberio tests detect seminal stains.

Option by option

  • A. Florence test; choline periodide crystals

    The Florence test uses iodine solution and detects semen.

  • B. Takayama test; haemochromogen crystals

    Takayama's test uses pyridine, glucose and alkali.

  • C. Barberio test; spermine picrate crystals

    The Barberio test uses picric acid and detects semen.

  • D. Teichmann test; haemin crystals (correct)

    Correct. Salt and acetic acid with heat give haemin crystals.

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 Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is D, Teichmann test; haemin crystals. In Teichmann's test, glacial acetic acid and salt convert haemoglobin to brown rhombic haemin crystals, a confirmatory test for blood.

Why is "Florence test; choline periodide crystals" not the answer?

The Florence test uses iodine solution and detects semen.

Why is "Takayama test; haemochromogen crystals" not the answer?

Takayama's test uses pyridine, glucose and alkali.

Why is "Barberio test; spermine picrate crystals" not the answer?

The Barberio test uses picric acid and detects semen.

What concept does this question test?

It tests Identification: Teichmann's test in Forensic Medicine. Takayama's test uses pyridine and gives pink feathery haemochromogen crystals. The Florence and Barberio tests detect seminal stains.

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 Identification: Teichmann's test?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic Medicine 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.