Well’s and PERC Criteria for Pulmonary Embolism : Mnemonic

Well’s Criteria (Modified and Simplified)

Mnemonic: CHADS (Remember, this is not the CHADS2 score for Atrial Fibrillation)

  1. Clinical features of DVT
  2. Cancer
  3. Heart rate > 100/min
  4. Hemoptysis
  5. Alternative diagnosis less likely
  6. DVT/PE in past
  7. Surgery in past 4 weeks or Immobilization for 3 days
Well’s criteriaOriginal scoreSimplified score
Clinical features of DVT (minimum of leg swelling and pain with palpation of the deep veins)31
Alternative diagnosis is less likely than PE31
Heart rate > 100 beats per minute1.51
Surgery in past 4 weeks or Immobilisation for more than 3 days1.51
DVT/PE in past1.51
Haemoptysis11
Cancer (on treatment, treated in the last 6 months, or palliative)11
Clinical probability
PE likelyMore than 4 pointsMore than 1 points
PE unlikely4 points or less1 point or less

PE algorithm

PERC (Pulmonary Embolism Rule-out Criteria)

Mnemonic: HAD CLOTS

1. Hormones (Estrogen use)

2. Age > 50 years

3. DVT/PE history

4. Coughing blood

5. Leg swelling

6. O2 <95%

7. Tachycardia >100/min

8. Surgery/truama within 4 weeks

If PE is unlikely or probability is low, PERC rule is used to decide if the assessment of D-dimer would be beneficial or not. If any 1 of the 8 criteria in PERC is met, D-dimer assay is beneficial.

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