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Wells score or gestalt before PERC?

July 13, 2016

Short Attention Span Summary

The PERC Rule for PE is only to be used when physician gestalt is low.  Some advocate using an objective score, such as Wells score, to determine if the PERC Rule may be applied rather than gestalt.  In this retrospective study of 377 patients, 2 subsegmental PEs would have been missed in patients with Wells score <2 and negative PERC.  Sensitivity for PERC was only 89% in this study.  It is hard to know what to do with this.  All data were collected retrospectively.  It would be challenging to calculate Wells and PERC scores by chart review, which is a major limitation.  Until this is confirmed in a larger, prospective study, I plan to continue using PERC rather than a low Wells + negative D-dimer method.  Too many patients will get unnecessary CTPA with that approach.

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Emerg Med J. 2016 Jun 10. pii: emermed-2016-205687. doi: 10.1136/emermed-2016-205687. [Epub ahead of print]

A retrospective analysis of the combined use of PERC rule and Wells score to exclude pulmonary embolism in the Emergency Department.

Theunissen J1, Scholing C1, van Hasselt WE1, van der Maten J2, Ter Avest E1.

Author information:

1Department of Emergency Medicine, Medical Centre Leeuwarden, Leeuwarden, The Netherlands.

2Department of Pulmonology, Medical Centre Leeuwarden, Leeuwarden, The Netherlands.



The pulmonary embolism rule-out criteria (PERC) rule is an eight-factor decision rule to support the decision not to order a diagnostic test when the gestalt-based clinical suspicion on pulmonary embolism (PE) is low.


In a retrospective cohort study, we determined the accuracy of a negative PERC (0) in patients with a low Wells score (<2) to rule-out PE, and compared this to the accuracy of the default algorithm used in our hospital (a low Wells score in combination with a negative D-dimer).


During the study period, 377 patients with a Wells score <2 were included. CT pulmonary angiography (CTPA) was performed in 86 patients, and V/Q scintigraphy in one patient. PE was diagnosed in 18 patients. 78 patients (21%) had a negative PERC score. When further diagnostic studies would have been omitted in these patients, two (subsegmental) PEs would have been missed, resulting in a sensitivity of 89% (64%-98%) and a negative likelihood ratio (LR-) of 0.52 (0.14-1.97). The default algorithm missed one (subsegmental) PE, resulting in a sensitivity of 95% (71%-99%) and an LR- of 0.25 (0.04-1.73).


The combination of a Wells score <2 and a PERC rule of 0 had a suboptimal sensitivity for excluding PE in our sample of patients presenting in the ED. Further studies are warranted to test this algorithm in larger populations.

Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

PMID: 27287004 [PubMed – as supplied by publisher]