Laboratory diagnosis of pulmonary thromboembolism

ABSTRACT

Twenty five patients with clinically suspected pulmonary embolism were studied by ventilation-perfusion lung scan [V/Q]. Twenty patients showed positive scan [low, indeterminant, and high probability] and 5 patients had negative scan. Beta-mode ultrasound with Doppler showed evidence of deep venous thrombosis in 50% of cases. Laboratory findings showed a raised plasma cross linked fibrin degradation products [FDPs] above 500 ng/ml in 85.7% of cases with high probability positive lung scan and elevated serum levels of C-reactive protein [CRP] above 50 mg/l in 85.7% of high probability scan. A normal level of serum CRP and/or plasma cross linked FDPs in blood taken within 4 days of onset of symptoms virtually excluded the diagnosis of pulmonary embolism. Other positive laboratory data in cases of pulmonary embolism diagnosed by lung scan were disturbed, arterial blood gases in 90% of cases, raised serum lactate dehydrogenase enzyme above 300 IU/l in 57.2%, aspartate transaminase enzyme above 40 IU/l in 28.6% of cases and low platelet count below 100,000/Cmm in 25% of cases