The most commonly missed diagnosis found at post mortem and the most over-diagnosed condition in medicine.
Not a day can go by without an admission to Ninewells with possible PE. There are guidelines for the management of suspected PE, both regional and national. I’ll run through the process of making a diagnosis of pulmonary embolus here.
The presenting signs and symptoms of PE are notably non-specific, and as such, the diagnosis is not easy to reach accurately. Fortunately there is help at hand.
Let’s start with In A Surgeon’s Gown:
Incidence | Very common, but not as common as we think... |
Age | Any age, but unusual in childhood |
Sex | Slightly more common in females than males |
Geography | Worldwide |
Predisposing Factors | Immobility, recent surgery, malignancy, thrombophillic states, pregnancy, major systemic illness, trauma, exacerbations of inflammatory bowel disease |
Macropathology | Thrombus forms in large volume, low flow veins, usually in the lower limbs. This becomes dislodged and passes into the pulmonary tree. |
Micropathology | Clot may reside in the main pulmonary trunk, right or left main pulmonary arteries, or lower branches of the pulmonary tree. |
Symptoms and Signs | Variable. Breathlessness, haemoptysis, pleuritic chest pain, tachycardia, tachypnoea. |
Treatment | Anti-coagulation: acutely with fractionated, or unfractionated heparin; chronically with warfarin, or fractionated heparin. Thrombolysis for life threatening PE. |
Prognosis | May be fatal - adverse features are systemic hypotension, bradycardia,and right ventricular failure. If the acute event is survived, the long term prognosis is good. Recurrence rates are low. |
So, what to do when someone comes into Ward 15 with a suspected PE.
Ninewells Hospital uses a slightly modified version of the the BTS national guideline on investigation of suspected pulmonary embolus. We ask two initial questions:
- Is the most likely diagnosis Pulmonary Embolus?
- Is there a major risk factor present? (Previous PE or DVT / Major Medical Illness / Recent Immobility / Major Surgery / Lower Limb Surgery or Trauma / Pregnancy / < 6 Weeks Post-Partum)
If the answer to both questions is “yes”, the patient needs imaging.
If the answer to one question is “yes”, you should proceed to D-Dimer measurement. If the D-Dimer is negative, PE can be ruled out. If the D-Dimer is positive, the patient needs imaging.
If the answer to both questions is “no”, PE can be ruled out.
Imaging modality should be V/Q scan if the CXR is normal, and CTPA if the CXR is abnormal. Fully anti-coagulate the patient while you wait for the imaging to confirm or refute the diagnosis. You can download the sticker we use in Ninewells to request a CTPA here.
V/Q scans are reported as low, intermediate and high probability. Those of low probability are taken as ‘negative’, and those with high probability as ‘positive’. If the V/Q is reported as intermediate, or inconclusive, it is usual for CTPA to be requested.
Look at the BTS guidelines on Pulmonary Embolism. They are due for update soon, but the 2004 guidelines are what we currently base our local practice on.
Other systems in use around Scotland and the UK are the Well’s Score, the Modified Well’s Score, and the Geneva score.
