Pulmonary embolism is a sudden blockage in a lung artery. Blockage usually is caused by a blood clot that travels to the lung from a vein in the leg. Because pulmonary embolism almost always occurs in conjunction with deep vein thrombosis, most doctors refer to the two conditions together as venous thromboembolism. Pulmonary embolism can be life-threatening, but prompt treatment can greatly reduce the risk of death.a
statistical analysis on pulmonary embolism resulted as the most of the studies carried a high risk of bias because of high or unclear risk relating to randomisation and blinding.Meta-analysis showed that, compared with heparin alone, or heparin plus placebo, thrombolytics plus heparin can reduce the odds of death (odds ratio (OR) 0.57, 95% confidence interval (CI) 0.37 to 0.87, P = 0.02, low quality evidence) and recurrence of PE (OR 0.51; 95% CI 0.29 to 0.89, P = 0.02, low quality evidence).