Compression Ultrasound of Lower Extremity Veins for Suspected DVT: AIUM 2024

Clinical Task and Source

The practical parameter AIUM Practice Parameter for the Performance of a Peripheral Venous Ultrasound Examination, 2024 Revision sets the framework for standard peripheral venous ultrasound: the examination should answer whether there is thrombosis, where it is located, how much it occludes the lumen, and whether there are signs of an acute or chronic process. For suspected deep vein thrombosis of the lower extremities, this is primarily a compression study in B-mode with Doppler clarification of blood flow.

It is important to formulate the direction and protocol not as “leg vessel ultrasound” in general, but as a study of the venous system for suspected DVT: side, clinical zone of symptoms, presence of previous DVT, anticoagulation, recent interventions, and availability of previous images directly affect the interpretation of residual changes.

Scope of Examination for Suspected DVT

A comprehensive examination of the lower extremity for suspected DVT includes the assessment of the common femoral veins in the groin area, the sapheno-femoral junction, the femoral vein in the thigh, the proximal deep femoral vein, the popliteal vein, and the deep veins of the calf, primarily the posterior tibial and peroneal veins. If symptoms extend beyond the standard accessible segment, more proximal venous outflow is assessed indirectly by spectrum and, if possible, directly by iliac veins.

The term “femoral vein” should be used without the term “superficial femoral vein” as this vein belongs to the deep system, and its thrombosis is DVT. The protocol should preferably name the anatomical segment rather than just stating “above the knee” or “below the knee.”

Compression Ultrasound Technique

Compression is performed in the transverse plane. The transducer is placed perpendicular to the skin, and pressure is increased until the walls of a normal vein collapse. If the lumen does not fully collapse with adequate compression, this is a key ultrasound criterion for thrombosis. The adjacent artery usually retains a round shape and serves as a depth and pressure adequacy guide.

Images without compression and with compression in key segments are documented. If visualization is limited by obesity, edema, pain, wound, cast, or postoperative changes, this is indicated in the conclusion as a limitation of the method, not masked by the phrase “no pathology detected.”

Role of Color and Spectral Doppler

According to AIUM 2024, Doppler modes are used as an addition to grayscale compression. Color mapping helps visualize the residual lumen in non-occlusive thrombosis, confirm the absence of flow in a segment inaccessible for compression, and assess collaterals. Spectral Doppler is used to assess the spontaneity, phasicity, and symmetry of venous flow.

Loss of normal phasicity or pronounced asymmetry of the spectrum in the common femoral veins may indicate a more proximal obstruction to venous outflow, including the iliac level. Such a sign does not replace direct visualization but should be reflected in the protocol and may change further diagnostic tactics.

Table: Ultrasound Interpretation of Venous Findings

Calf Veins: When It Is Essential to Examine

Including deep calf veins makes the study more complete in cases of calf pain and swelling, local tenderness along the veins, cancer history, postoperative state, and other situations where isolated distal thrombosis is clinically significant. Paired posterior tibial and peroneal veins are assessed alongside their corresponding arteries. Calf compression is technically more challenging, so proper focus depth, sufficient gel, and a combination of grayscale mode with color Doppler are especially important.

If calf veins are not visualized, it is unacceptable to automatically transfer a negative result from proximal veins to the entire limb. The wording should clearly separate “no proximal DVT detected” and “deep calf veins not fully assessed.”

Superficial Veins and Junction Areas

In suspected DVT, proximal parts of the superficial venous system, especially the great saphenous vein at the sapheno-femoral junction and the small saphenous vein at the sapheno-popliteal junction, should not be ignored if they are accessible and clinically relevant. Superficial thrombosis approaching a deep junction or transitioning into the deep system changes clinical risk and should be described anatomically accurately.

After venous interventions, ablation, or sclerotherapy, it is useful to indicate whether the finding is an expected post-procedural change or if there is an extension of the thrombotic process into the deep vein. AIUM 2024 also considers venous mapping before interventions as a separate task of peripheral venous ultrasound.

What Must Be Included in the Conclusion

The conclusion should answer several questions: is there DVT; which limb and which segments are affected; is the thrombus occlusive or non-occlusive; does the process appear acute, chronic, or mixed; which segments could not be assessed; is there a comparison with a previous study. If significant thrombosis is detected, the result should be promptly communicated to the treating physician according to the local protocol for critical findings.

The phrase “echosigns of thrombosis” without a level is insufficient. The optimal wording: “non-compressible thrombotic material in the popliteal vein extending into the posterior tibial veins” or “chronic post-thrombotic changes in the femoral vein with no signs of new occlusive thrombosis.”

Repeat Ultrasound at the End of Anticoagulation

A relevant addition to the AIUM 2024 revision is the recommendation to perform repeat venous ultrasound closer to the end of the anticoagulation course to establish a new baseline state. This is especially important after confirmed DVT because residual non-compressibility, parietal echogenic masses, and recanalized channels may persist and later mimic recurrence.

Such a baseline study should not automatically be interpreted as “treatment inefficacy” if there are no new clinical data and no increase in thrombotic involvement compared to the initial study. Its task is to document post-thrombotic anatomy so that subsequent episodes of pain or swelling can be compared with the new reference.

Typical Protocol Errors

• Limiting the study to only the groin and popliteal area without indicating that it was a limited protocol.
• Using the term “superficial femoral vein,” creating a risk of underestimating DVT.
• Negative conclusion when calf veins are not examined without describing the limitation.
• Diagnosing “DVT recurrence” without comparison to previous images in the presence of chronic post-thrombotic changes.
• Relying solely on color Doppler without full compression where compression is technically possible.

For the practicing physician, the main standard is simple: compression remains the central test, Doppler clarifies hemodynamics and difficult zones, and a quality conclusion should be anatomically accurate and comparable over time.