the next video in my clinical scale series is on Wells Criteria Wells Criteria helps you assess the risk of a patient having a pulmonary embolism and to be more specific the purpose of Wells Criteria is not to determine necessarily who has a PE the purpose of Wells Criteria is to determine what step should you take in your workup or in your diagnosis to rule in or rule out a PE the reason that this is used ful is when a patient comes into the emergency room let's say it's on your exam they give you a patient coming into the Ed you don't have X-ray vision right you can't just stare at their chest and be like ah yes I see a PE inside of your pulmonary vascular chair and then know what to do in real life what's happening is you can't give every patient CT angiography because we just don't give everybody CTS that's not cost- effective it's not safe so the question is who do you order the D dier for and who do you order the CT angiography for so this shows up on step two on level two on your internal medicine shelf on your clinical rotations and that's what the Wells Criteria is for depending on how they score in Wells Criteria you certain patients you get the CT certain patients you can just do dher and so this this score helps stratify risk and determine next steps in your workup so let's go through the criteria unfortunately if you've been looking at my clinical scale series you know that in most of for example like has bled Chad's vasque the letters all stand for something but in Wells that's not the case so you unfortunately have to recognize or memorize what is used to calculate the score so the first thing that you're scoring is whether the patient has clinical signs and symptoms of a deep vein thrombosis so you're going to be looking for that calf pain that tender calf if yes three points if no zero points the next is whether an alternative diagnosis is less likely than a PE so this is a bit subjective but if a patient on your exam has buzzwords and findings that are probably more specific to an alternative diagnosis then in in that case you probably don't score any points here but if PE is the most likely diagnosis then you're going to score three points again if you're taking an exam it's going to be really obvious they're going to give you the Cardinal features of a DVT plus or minus a PE if they want you to pick something else they're going to give you buzzwords and findings with very high specificity for something that's not a pulmonary embolism or not a DVT so if the patient has a heart rate that's greater than 100 if yes that's one and a half points if no zero points because usually when you've got a DBT or when you've got a PE patient will be tacky especially on exams on usmar comx this is going to be I'm going to guess 100% specific to if they want you to identify a PE the next criteria pay very close attention to the timeline here so if the patient has either been immobilized in the past 72 hours or had surgery in the past four weeks if either one of those are true that's yes which equals one and a half points if no zero points now this is going to be really obvious on your exam what the test writer will do is they like to go after immobilization so what they're going to do is they're either going to tell you that the patient had surgery 3 days ago or 5 days ago it'll be obviously within the past four weeks or they'll give you a patient who took some super longdistance trip and essentially what they're implying is that the patient didn't move or was on an airplane for like 16 hours something to that effect it's going to be grossly obvious that they had surgery or that they were immobilized and usually because it's a 72-hour cut off for immobilization but a 4-we cut off for surgery if the test riter is going to be nice they'll give you within 72 hours regardless of if they're talking about immobilization or surgery that said if you're taking an in-class exam if you're taking a shelf they get a little fancy and sometimes they'll give you a surgery that's 3 weeks old and you have to remember that surgery technically counts within four weeks so this is pretty specific keep that in mind the next one is fairly obvious if the patient has ever had a history of a deep vein thrombosis or a pulmonary embolism that's one and a half points history of dbtp confers a higher risk of future dbtp so if yes that's one and a half points the next criteria is if the patient has hemoptisis if yes one point if no zero points and then the last thing that you're scoring is malignancy now I want to be clear on malignancy that means either current malignancy treatment for malignancy within the past six months or they are paliative if any of those are true you give a point and if none of those are true the patient gets zero points so here's the interpretation you basically go through all of these categories you come up with a score and now you have this is why we do the wells score the Wells Criteria what do I do to diagn or you know essentially rule in or rule out dbtp so if their score was from 1 to 4 or I should say zero to four their risk of pulmonary embolism is quote unlikely the next step if this patient was being assessed for possible dbtp would be dher which of course is just a blood test right it's a it's a lab draw so because the PE risk is lower and technically unlikely by literature that's looked at this you can just do the blood test if the D dier on a blood test for a patient who is scoring one to four is positive then the next step and this is for those of you who will be taking step two level two step three level three after the D dier is positive then you get the CTA but your first step is going to be D dier alternatively if you calculate your Wells Criteria and the score is five or greater their risk of PE is likely and so you don't want to waste time with the D dier because if you get the blood test depending on what that blood test shows you're going to get the CTA anyway because their score is so high in this case you jump right to the CTA right you go right to the CT and geography now some research that has looked at this found that over 20% of patients who went directly to CTA indeed had a diagnosis of pulmonary embolism and so it's for this reason that a high Wells score we go right to the CTA and we're less concerned about the potential risks associated with the CT so when you're taking step two level two your shelves you're on rotations all you need to remember is that if their score is five or more you do CTA or you do angiography and so the way that I've always memorized this is that angio has five letters if angio has five letters then five or more points equals angio and angio is a short way to say CTA or CT angiography so that is your Wells Criteria good luck