In vitro pleural fluid clottability and fibrinogen content.

Twenty-three specimens of pleural fluid from 23 patients were examined for quantitative fibrinogen, total protein levels, and for clottability in vitro using the recalcification time. Of the 19 specimens of pleural fluid from patients without loculation, 11 (seven exudates) had no detectable fibrinogen; another 8 (six exudates) had a mean fibrinogen level of 55.0 +/- 10.2 mg percent, and a mean recalcification time of 19.4 +/- 2.6 minutes. The pleural fluids from the four patients with loculation had no detectable fibrinogen. The only fluids containing fibrinolytic activity were from the nonloculated non-fibrinogen-containing group. No correlation existed between pleural fluid/plasma total protein ratios and pleural fluid/plasma fibrinogen ratios. In vitro clottability in this study did not reflect the in vivo tendency for coagulation and loculation.