When to Order Imaging for Suspected PE

When to order imaging for suspected pulmonary embolism

Imaging decisions for suspected PE are gated by clinical risk stratification and, where appropriate, D-dimer. CT pulmonary angiography (CTA chest) is the definitive imaging study when imaging is indicated. Acutely unstable patients belong in an emergency setting; this guide supports outpatient ordering for stable patients in whom the workup is being completed.

Stratify before you image

Use a validated clinical decision tool (Wells, revised Geneva, or PERC for very low-probability patients) to estimate pre-test probability. Low-probability patients with a negative high-sensitivity D-dimer do not need imaging. Moderate or high pre-test probability moves directly to imaging or to D-dimer first depending on the rule.

CTA chest is the test

CT pulmonary angiography with IV contrast is the highest-sensitivity widely available test for PE and is the default outpatient study when imaging is indicated. Order it with the specific PE protocol so the contrast bolus and timing are optimised for pulmonary arterial enhancement.

When CTA is contraindicated

Patients with contrast contraindications (severe contrast reaction history, certain renal scenarios) cannot complete a CTA-based PE workup at Precise. For these patients, the workup needs to continue outside our network at a facility that offers an alternative imaging pathway — do not delay diagnostic evaluation for high-probability patients while alternative arrangements are made.

Pregnant patients

PE workup in pregnancy is a coordinated decision with the obstetrician, weighing the risks of CTA contrast and radiation against the risks of missed diagnosis. We perform CTA chest with appropriate dose optimisation when ordered; institutional preference may favour an alternative pathway.

Ordering with Precise

CTA chest with IV contrast is available across the network with cardiothoracic and body imaging sub-specialty reads. Mark STAT when the clinical urgency warrants; STAT targets a ≤ 2-hour read with critical findings phoned to the ordering provider.

Provider FAQ

Questions referring offices ask first.

When should I send to the ED instead of ordering outpatient CTA?

Any patient with hypoxia, hypotension, significant tachycardia, syncope, or clinical concern for instability belongs in the ED, not in an outpatient queue.

Do I need a D-dimer before ordering CTA?

Only for low or moderate pre-test probability. High-probability patients go directly to imaging.

Educational reference for referring providers. Not a substitute for clinical judgement or the current official appropriateness criteria. References imaging modalities offered by Precise; modalities not in our network are out of scope.

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