Ultrasonography of deep vein thrombosis of the lower extremity

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Author: Mikael Häggström [notes 1]



Wells score or criteria help categorize patients into low risk versus high risk:

  1. Active cancer (treatment within last 6 months or palliative): +1 point
  2. Calf swelling ≥ 3 cm compared to asymptomatic calf (measured 10 cm below tibial tuberosity): +1 point
  3. Swollen unilateral superficial veins (non-varicose, in symptomatic leg): +1 point
  4. Unilateral pitting edema (in symptomatic leg): +1 point
  5. Previous documented DVT: +1 point
  6. Swelling of entire leg: +1 point
  7. Localized tenderness along the deep venous system: +1 point
  8. Paralysis, paresis, or recent cast immobilization of lower extremities: +1 point
  9. Recently bedridden ≥ 3 days, or major surgery requiring regional or general anesthetic in the past 12 weeks: +1 point
  10. Alternative diagnosis at least as likely: −2 points[1]
Less than 1: Low risk[2][1]
Greater than 2: High risk[2][1]
Swedish algorithm.[3]

The threshold for normal versus high D-dimer is generally 500 ng/mL or 0.5 mg/L.[4] In pregnant or elderly patients, corresponding D-dimer ranges need to be used.[notes 2]

In certain circumstances, it may also be indicated in suspected pulmonary embolism, see pulmonary embolism.


Doppler ultrasonography showing absence of flow and hyperechogenic content in thrombosed femoral vein.

Start as high as possible in the inguinal region where you can clearly see the external iliac vein, and then follow the femoral vein and popliteal vein with the probe. Compress the vein at regular distances, such as totaling at least 7 locations. Look for:

  • Hyperechoic content.
  • Absence of compressibility. However, adequate compression is usually not possible by the area where the vein passes through the adductor hiatus.

A decrease in Doppler flow raises the suspicion, but has less sensitivity and specificity.

Lower leg

If a lower ultrasound of the lower leg is indicated in the algorithm above, also evaluate the posterior tibial veins (at least distally near the ankle), the fibular veins (either beneath the posterior tibial vein, better seen when going about half way up the lower leg) as well as the anterior tibial vein (at least proximally).


  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Radlines:Authorship for details.
  2. Pregnant patients
    Upper limit of reference range for D-dimer:
    Units Nonpregnant
    First trimester Second trimester Third trimester
    mg/L or µg/mL < 0.5 < 0.95 < 1.29 < 1.7
    µg/L or ng/mL < 500 < 950 < 1290 < 1700
    nmol/L < 2.7 < 5.2 < 7.1 < 9.3

    Reference: Reference Values During Pregnancy at perinatology.com. Retrieved October 2014.

    Elderly patients

    Patient’s age in years × 10 µg/L (or x 0.056 nmol/L) for patients aged over 50 years for the suspicion of venous thromboembolism (VTE).

    ". J Fam Pract 63 (3): 155–8. March 2014. PMID 24701602. 

    • Raja, Ali S.; Greenberg, Jeffrey O.; Qaseem, Amir; Denberg, Thomas D.; Fitterman, Nick; Schuur, Jeremiah D. (29 September 2015). "Evaluation of Patients With Suspected Acute Pulmonary Embolism: Best Practice Advice From the Clinical Guidelines Committee of the American College of Physicians

    ". Annals of Internal Medicine 163 (9): 701. doi:10.7326/M14-1772. PMID 26414967. 


  1. 1.0 1.1 1.2 "Clinical probability and D-dimer testing: How should we use them in clinical practice? ". Semin Respir Crit Care Med 29 (1): 15–24. 2008. doi:10.1055/s-2008-1047559. PMID 18302083. 
  2. 2.0 2.1 "Diagnosis of DVT: Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines ". Chest 141 (suppl 2): e351S–e418S. 2012. doi:10.1378/chest.11-2299. PMID 22315267. 
  3. Docent Henry Eriksson, Med dr, överläkare Fariba Baghaei, Specialistläkare Valerie Bockisch, Professor emerita Margareta Hellgren, Docent Leif Lapidus, Överläkare Per-Åke Moström, Med dr, Överläkare Vladimir Radulovic, Överläkare Lennart Stigendal. Djup ventrombos, DVT. Internetmedicin. Updated 2017-06-11
  4. "Plasma measurement of D-dimer levels for the early diagnosis of ischemic stroke subtypes ". Archives of Internal Medicine 162 (22): 2589–93. 2002. doi:10.1001/archinte.162.22.2589. PMID 12456231. Archived from the original. .