ObjectivesTo determine if mandatory adherence to a diagnostic protocol increases the rate of computed tomography pulmonary angiographies (CTPAs) positive for pulmonary embolism (PE)—the so-called diagnostic yield. Further, we aim to identify factors associated with this diagnostic yield.MethodsWe included all patients with suspected PE requiring CTPA from 9 January 2014 t0 3 June 2014. The requesting physicians were forced to follow diagnostic workup for PE by calculating a Wells score and, if necessary, determining D-dimer level. The percentage of positive CTPA scans was calculated and compared with our previous cohort (Walen et al. Insights Imaging 2014;5(2):231–236). Odds ratios were calculated as a measure of association between dichotomous variables and CTPA findings.ResultsOf 250 scans, 74 were positive (29.6 % [95 % CI, 24.3-35.5 %]) and 175 were negative (70 %). The percentage positive scans increased with 6.6 % and the percentage negative scans decreased with 3.1 %. This change was statistically significant (p = 0.001). Independent clinical predictors of diagnostic yield were previous deep venous thrombosis (DVT) (OR, 3.22; p = 0.013) and clinical signs of DVT (OR, 2.71; p = 0.012). Chronic obstructive pulmonary disease (COPD) was negatively associated with PE (OR, 0.33; p = 0.045).ConclusionsThis study shows that mandatory adherence to a diagnostic protocol increases the yield of CTPA for PE in our centre.Main Messages• Mandatory adherence to diagnostic protocol increases the yield of CTPA for PE• Previous DVT and signs of DVT were associated with a higher yield• No patients with a low Wells score and a low D-dimer had PE