Perforation of a hollow organ during trauma may be hard to diagnose by diagnostic peritoneal lavage since these organs bleed minimally and it may take several hours for an inflammatory response to be manifest to spilled contents. The cell count ratio done on lavage fluid and blood can help identify those patients with a perforated hollow viscus.


Measured analytes (done by automated analyzer unless the count is too low, in which case a manual count with a hemocytometer is performed):

(1) lavage WBC

(2) lavage RBC

(3) blood WBC

(4) blood RBC


cell count ratio =

= ((lavage WBC count) / (lavage RBC count)) / ((blood WBC count) / (blood RBC count))



• cell count ratio >= 1.0: positive for hollow viscus perforation

• cell count ratio < 1.0: negative for hollow viscus perforation


Performance of cell count ratio in predicting hollow viscus perforation

• sensitivity 100%, specificity 97%

• positive predictive value: 89%, negative predictive value: 100%

• accuracy: 98%


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