Lower-Limb Venous Doppler (DVT)

Compression ultrasound with colour and spectral Doppler is the primary imaging test for suspected lower-limb deep vein thrombosis. The single most reliable sign is loss of full compressibility of the vein under transducer pressure. Doppler augmentation and phasicity provide supportive haemodynamic information, particularly for the deep femoral and iliac segments that are difficult to compress.

Indications

Clinically suspected deep vein thrombosis (unilateral swelling, pain, tenderness)
Elevated D-dimer or intermediate/high Wells pre-test probability
Suspected recurrent DVT or extension of known thrombus
Pre-operative or high-risk screening in selected patients
Assessment of chronic venous changes and post-thrombotic syndrome

Contraindications & Cautions

No absolute contraindications; ultrasound is non-invasive and safe
Overlying wounds, casts or severe oedema may limit compression technique
Marked obesity or gas can obscure the iliac veins and calf
Do not apply firm compression directly over a suspected mobile fresh thrombus if avoidable

Patient Preparation

No fasting required
Supine with the leg externally rotated and knee slightly flexed
Reverse Trendelenburg (10-20 degrees) to distend the deep veins and pool blood
For popliteal and calf veins position prone or sitting with the leg dependent
Warm the limb to promote venous filling

Technique & Parameters

Linear 5-12 MHz probe for common femoral to popliteal veins; curvilinear 3-6 MHz for iliac veins or large limbs
Grey-scale transverse compression every 1-2 cm from the common femoral vein to the popliteal and calf veins
A patent vein walls fully coapt under gentle pressure; incomplete coaptation indicates thrombus
Colour Doppler to demonstrate luminal filling and identify non-occlusive filling defects
Spectral Doppler in the common femoral vein to assess spontaneous, phasic (respiratory-varying) flow
Distal augmentation (calf squeeze) to confirm patency and unmask non-occlusive proximal thrombus

Systematic Review

Common femoral vein: compressibility, spontaneous phasic flow and response to augmentation
Femoral (superficial femoral) and deep femoral veins along the thigh at short intervals
Popliteal vein and the tibioperoneal trunk
Calf veins (posterior tibial, peroneal, gastrocnemius/soleal) where clinically indicated
Great and small saphenous veins for superficial thrombophlebitis
Assess for extrinsic causes of swelling: Baker cyst, haematoma, mass

Key Findings & Significance

Acute DVT: non-compressible, distended vein with hypoechoic/anechoic intraluminal thrombus and absent colour filling
Non-occlusive thrombus: partial colour filling defect with a compressible residual lumen
Loss of respiratory phasicity or a continuous (non-phasic) common femoral waveform suggests proximal/iliac obstruction
Absent or blunted response to distal augmentation indicates intervening occlusion
Chronic thrombus: echogenic, retracted, wall-adherent thrombus with recanalisation and collaterals
Superficial thrombophlebitis: non-compressible echogenic superficial vein; note proximity to the saphenofemoral junction

Differential Considerations

Leg swelling/pain: acute DVT vs chronic post-thrombotic change vs cellulitis vs lymphoedema
Non-compressible vein: acute thrombus vs chronic wall-thickened vein vs technical (inadequate pressure)
Absent flow: occlusive thrombus vs vein spasm/low flow vs proximal obstruction
Extrinsic mass: ruptured Baker cyst, haematoma, abscess, tumour
Continuous CFV waveform: iliac/IVC thrombosis vs extrinsic pelvic compression vs pregnancy

Pearls & Pitfalls

Compressibility is the primary criterion; colour and spectral Doppler are supportive, not a substitute
A continuous, non-phasic or asymmetric common femoral waveform is an indirect clue to non-visualised iliac thrombus
Distinguish acute (soft, distended, hypoechoic) from chronic (echogenic, retracted, wall-adherent) thrombus to guide management
Isolated distal (calf) DVT may warrant follow-up rather than immediate anticoagulation per local protocol
Always look for an alternative cause of symptoms such as a Baker cyst or haematoma when veins are patent

Structured Report

State examined segments, probe and whether a complete or limited (2-point/proximal) protocol was used
Report compressibility, thrombus presence, extent, acuity and the most proximal and distal levels involved
Describe colour filling, phasicity and augmentation response
Note incidental findings (Baker cyst, superficial thrombophlebitis, mass)
Give an impression stating presence/absence, level and chronicity of DVT and recommend follow-up if limited

References

AIUM-ACR-SPR-SRU Practice Parameter for the Performance of Peripheral Venous Ultrasound Examination
Needleman L et al. Ultrasound for Lower Extremity DVT: SRU Consensus Conference. Circulation 2018
Hamper UM et al. Ultrasound Evaluation of the Lower Extremity Veins. Radiographics
ACCP/CHEST Guidelines on Antithrombotic Therapy for VTE Disease

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.

Lower-Limb Venous Doppler (DVT)

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References