PE: Pain, Puzzles and PERC

Judging by the flurry of comments on two recent EMCrit posts (OK, about half of them are mine…) Scott ‘20 inches‘ Weingart has cracked open a can of pulmonary embolus-shaped worms.

First he featured a fascinating intellectual slugfest between himself and the cerebrally top-heavy David Newman — who you will know as the brilliant ER doc (with help from his friends) behind SMARTEM, TheNNT and even the Annals of Emergency Medicine podcast (be sure to catch his great interview ‘What would Hippocrates Do?‘ on Rob O’s ERCast).

Check out all 15 rounds of this ‘clash of the titans’ at EMCrit: A Debate on PE Rules.

One things for sure, when it comes to PE, there is no winner. The diagnosis, for many, reasons is a constant thorn in side of emergency physicians the world over. Perhaps the best comment came from Broome Docs‘ Dr Casey Parker who shows that being in a remote location forces one to consider the threshold for investigation more carefully. Indeed, perhaps we should all ask ourselves:

“Would you still want to investigate the patient for PE if it involved flying them 1000 km?”

However, emerging from the blood spattered PE arena, Scott posted a nifty flowchart summarising a reasonable approach to using Wells, the PERC rule and clinical judgement to decide when you can safely rule out PE, and when you need to go on to further imaging.

Scott Weingart's flowchart (Source:

So far, in a couple of days, this post has clocked up over 26 comments. The first is a classic — and exemplifies why blogs and podcasts beat journals hands down everytime. Thank you Mike J! You’ll never see a comment in a journal start with:

“Ok Weingart, i’ll bite. Fueled by the fact that i am post shift, it is 3 am and the dogs woke me up and i have had a beer. This algorithm is completely nuts! Maybe i am an ignorant slut but……..”

To Mike’s credit he revisits the post after paying off his sleep debt and blowing a zero on the alcometer.

The other spin off from all of this are the threats I’ve received from our budgie-smuggling friend Rob Orman regarding an upcoming ERCast PE feast — that’s one to look out for. But, on a side note, what is it with these podcast guys? It seems both Orman and Weingart have horribly mishapen cortical homunculi… the mouth and ears are all out of proportion. You send them an email and they send you back an mp3 audio recording with a background of laboured breathing while they multitask riding a bicycle, placing a central line and firing off responses to their latest podcasts… To me, that’s not normal.

Anyway, if you can stomach anymore on the damnation that is D-dimer or the puzzle of the PERC rule, you might want to check out these Case-based Q&A’s from the LITFL archives:



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  1. says

    Also be sure to read Newman and Schriger’s editiorial in the most recent issue of annals:

    Newman DH, Schriger DL. Rethinking testing for pulmonary embolism: less is
    more. Ann Emerg Med. 2011 Jun;57(6):622-627.e3. PMID: 21621091.

    Here are two excerpts:


    To improve our future, we must confront our past. A stirring narrative (“pulmonary embolism is deadly”) and an unsubstantiated faith in therapy have led to aggressive testing, despite an evidence base that does not support this approach. Thus, we could begin by confronting the knowledge gap: We have not yet defined which patients with pulmonary embolism are at risk for a “next one” event, nor have we established whether anticoagulation is effective therapy for pulmonary embolism. The investigation by Barritt and Jordan10 would not be considered important or publishable today, and the study by Nielsen et al,13 the only well-controlled trial of anticoagulation of which we are aware, suggests no benefit to anticoagulation. In addition to being unproven, this modality is risky and complicated and consumes substantial resources, making placebo-controlled efficacy trials both essential and ethical. Research to improve characterization of clot burden in healthy controls and high-quality studies of prognosis will also help us learn to identify those pulmonary embolisms that may benefit from diagnosis and treatment

    The diagnostic approach to pulmonary embolism and our view of the condition are at a crossroads. We are testing too much and at risk of compromising our oath. The emphasis on pursuing and treating this diagnosis should shift to a group at higher risk of clinically important outcomes, patients with physiologic compromise. With a new emphasis on research for both therapy and diagnosis, and vigilant monitoring of outcomes, we can reduce testing while increasing benefit. Less will be more.