For people who present with signs or symptoms of DVT, such as a swollen or painful leg, assess their medical history and perform a physical examination to exclude other causes NICE NG158.
If DVT is suspected, use the 2‑level DVT Wells score to estimate clinical probability NICE NG158.
For a Wells score of 2 points or more (DVT likely), offer a proximal leg vein ultrasound scan with results available within 4 hours if possible, and a D‑dimer test if the scan is negative NICE NG158.
If a proximal leg vein ultrasound scan cannot be obtained within 4 hours, offer a D‑dimer test, interim therapeutic anticoagulation, and a scan within 24 hours NICE NG158.
If the ultrasound scan is positive, offer or continue anticoagulation treatment or mechanical intervention if anticoagulation is contraindicated NICE NG158.
If the Wells score is 1 point or less (DVT unlikely), offer a D‑dimer test with results available within 4 hours, or interim anticoagulation while awaiting results if testing is delayed NICE NG158.
If the D‑dimer test is negative, stop anticoagulation and discuss signs and symptoms of DVT with the patient NICE NG158.
If the D‑dimer test is positive, proceed with a proximal leg vein ultrasound scan, and follow subsequent actions based on the scan result NICE NG158.