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Saturday, 9 March, 2002, 00:36 GMT
Scanner helps detect internal bleeding
Crash victim
Crash victims often suffer internal bleeding
Scientists have discovered a powerful ultrasound scan could help doctors check patients for internal bleeding.

Doctors often find it difficult to detect internal bleeding, a potentially life-threatening condition.

However, an ultrasound technique tested in the USA allows emergency doctors to check for haemorrhages quickly at a patient's bedside.


Sometimes it's hard to be sure if patients are bleeding or not

Xuegong Shi, ATL Ultrasound
But a doctor in the UK is sceptical of its potential for A&E departments.

Xuegong Shi at ATL Ultrasound in Bothell, Washington, who recently left the University of Washington in Seattle, said: "Sometimes it's hard to be sure if patients are bleeding or not.

"You can think they're stable, but they might be slowly bleeding to death."

While ruptured arteries are relatively easy to spot, blood leaking from veins is much tougher to identify and locate, says Mr Shi in an article in New Scientist.

It tends to fill the body's natural cavities and these clotted blood pools are difficult to detect because coagulated blood reflects ultrasonic waves.

Patients who are well enough to be moved can be injected with a chemical that shows up on an X-ray image.

However, seriously injured patients sometimes need to be examined on the spot.

Mr Shi found that by turning up the power on a Doppler ultrasound scanner he was able to check for internal bleeding.

While standard ultrasound scanners simply measure the time it takes for reflected sound waves to return, the Doppler scanner also looks at how the wavelength of the reflected wave changes.

If it has become shorter, the surface it bounced off must be moving towards the scanner.

The faster the surface is moving, the more the wavelength changes.

With the scanner at high power, the sound waves force the clumps of red blood cells to flow in the leaked pools of blood.

Scepticism

Because the ultrasound does not make any surrounding organs move, the pools of blood stand out in a Doppler scan.

The researchers tested the technique on small bags of blood implanted in pigs.

The effect requires a power level of 20 watts per square centimetre, which is more than 25 times normal intensity.

This level is still safe, says Mr Shi, and far below the energies used in experiments to cauterise tissues with ultrasound.

Mr Shi says the technique would be useful on battlefields where severely injured soldiers need to be checked quickly with a minimum of diagnostic equipment.

Consultant for A&E services at St Mary's Hospital in Paddington, Dr Ruth Brown, says the Doppler scanner is already used in hospitals when looking for blood clots or aneurisms.

She questions its suitability for A&E departments.

She said: "They have a point, there is a very small number of people for whom it is difficult to diagnose bleeding, but it is a tiny group.

"Diagnosis difficulties may be due to a resources limitation or may be because you have to make some kind of assessment of who is most likely to have internal bleeding.

"Not all bleeding is life threatening and even if you have got bleeding, it doesn't mean you have to take them to theatre.

"Whether Doppler scanning has any application for A&E is probably less likely."

See also:

31 May 00 | Health
Ultrasound 'halts bleeding'
29 Jun 99 | Health
Headache's secrets revealed
22 Oct 99 | Health
Bleeding risk of anti-depressants
13 Apr 00 | Health
Aspirin cuts blood clot danger
18 Apr 00 | Medical notes
Cerebral aneurism
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