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Likelihood Ratio (LR) in Emergency Medicine

10/27/2012

What does it hide behind a negative X-Ray?


Clinical Scenario

A 33 y/o woman, comes to the ED because of a sudden emithorax pain on the left in basal region. The pain is described as stabbing, well localized, it worsen with inspirium …a pleuritic pain, no cough, no fever, not hemoptysis. She smokes, she does not take any medication. 
Chest x ray is normal. You receive blood test: WBC 7.500/mcL, CRP 20 mg/dl , D-dimer 603 ng/ml.



Maybe is not a wall chest pain, but in which direction this test are carrying you?















Conclusion 

As we have seen in previous post there is not a clinical sign that can reduce or increase the probability to find a radio-occult lesion in patient with pleuritic pain, and we left with the question:  “Will we find the answer in blood test?”
As you can see above, the absence of all the three blood parameters, in patient with a normal clinical examination, can alone rule out the possibility to find a radio-occult lesion with an LR- of 0, but what if one of them is positive? We need to go further, but where? Is CT scan the answer?


Bibliography

American Journal of Emergency Medicine (2012) 30, 317–324 
A comparison of different diagnostic tests in the bedside evaluation of pleuritic pain in the ED 
Giovanni Volpicelli M et al.

Ilenia Spallino

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