Injuries: railway-track bruise: 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 · Injuries: railway-track bruise

Sample item

A man beaten with a lathi has two parallel linear bruises about 2 cm apart on his back, with a pale, unbruised strip between them. What explains the central pallor?

ABlood is squeezed sideways from vessels compressed under the rod, which then rupture at its marginsBTwo separate blows were struck with two different weaponsCVessels directly beneath the centre of the rod are the only ones that ruptureDReactive vasospasm of the skin produced by cold at the time of injury

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

The answer and the reasoning

A. Blood is squeezed sideways from vessels compressed under the rod, which then rupture at its margins

A cylindrical weapon such as a stick or cane compresses the tissues under its centre and displaces blood towards the edges, where the stretched vessels rupture. This gives the typical railway-track or tramline bruise, a pale centre between two parallel bands of haemorrhage. It indicates a blow with a rod-like object.

Option by option

A. Blood is squeezed sideways from vessels compressed under the rod, which then rupture at its margins (correct)
Correct. Compression displaces blood laterally, so only the margins bleed.
B. Two separate blows were struck with two different weapons
A single rod produces both lines, so two weapons are not needed to explain it.
C. Vessels directly beneath the centre of the rod are the only ones that rupture
The compressed central vessels are protected from rupture, which is why the centre is pale.
D. Reactive vasospasm of the skin produced by cold at the time of injury
Cold vasospasm is not part of the mechanism and the pattern follows the shape of the weapon.

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 Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is A, Blood is squeezed sideways from vessels compressed under the rod, which then rupture at its margins. A cylindrical weapon such as a stick or cane compresses the tissues under its centre and displaces blood towards the edges, where the stretched vessels rupture.

Why is "Two separate blows were struck with two different weapons" not the answer?

A single rod produces both lines, so two weapons are not needed to explain it.

Why is "Vessels directly beneath the centre of the rod are the only ones that…" not the answer?

The compressed central vessels are protected from rupture, which is why the centre is pale.

Why is "Reactive vasospasm of the skin produced by cold at the time of injury" not the answer?

Cold vasospasm is not part of the mechanism and the pattern follows the shape of the weapon.

What concept does this question test?

It tests Injuries: railway-track bruise in Forensic Medicine. This gives the typical railway-track or tramline bruise, a pale centre between two parallel bands of haemorrhage. It indicates a blow with a rod-like object.

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 Injuries: railway-track bruise?

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.