 The Investigators hypothesize that the distribution of hospital stay duration for PE will have a standard deviation of 4 days. The I vestigators also hypothesize that the mean duration of hospital stay will be reduced by at least 15 in PE patients whose treating physician will be randomised to formally use PESI and by 5 in PE patients whose treating physician will not be randomised to formally calculate PESI. Low-risk PE patients are almost 50 of all PE population. Therefore, with an α error of 0.05 and a statistical power 1-β error of 80, 200 patients for each group a total of 400 patients need to be enrolled to find a statistically significant difference p0.05 between the mean hospital stay length. As the variable hospital stay length will have a non-normal distribution and needs to be expressed and reported as median, 10 extra patients need to be enrolled to reach a statistically significant difference with the previous statistical assumptions. 