How to Dictate a Lower Extremity Venous Duplex: Compressibility, Acute vs Chronic, and the Pelvic Window

The venous duplex looks like the simplest study on the list — the vein either squishes or it doesn't — and that is exactly why the reports are so often bad. The exam is binary at each station but the report has to answer three harder questions: which segments, how old is the clot, and what about the veins the probe never touched. A report that only says "no DVT" has answered one question out of three.

Compressibility is the exam

The diagnostic maneuver is transverse compression every 2 cm or so: a normal vein's walls coapt completely under probe pressure. Anything less — partial compression, a vein that dents but won't close — is thrombus until proven otherwise. Color and spectral Doppler are supporting actors; grayscale compression is the test, and your report should be organized around where it was performed.

Dictate segment by segment, proximal to distal, both the segments examined and their result:

• Common femoral vein (including the saphenofemoral junction)
• Proximal deep femoral vein
• Femoral vein — proximal, mid, distal
• Popliteal vein
• Calf veins when imaged: posterior tibial and peroneal pairs; gastrocnemius and soleal veins if evaluated

One naming rule that prevents actual patient harm: the vessel formerly called the "superficial femoral vein" is a deep vein, and thrombus in it is a DVT requiring anticoagulation. Clinicians have read "superficial" and withheld treatment. Call it the femoral vein, full stop — the nomenclature changed for exactly this reason.

Acute versus chronic: the features

Anticoagulation decisions hinge on whether this is fresh clot or old scar, so the report must commit, hedge explicitly, or say "indeterminate" — but never stay silent. The widely taught discriminators:

Acute thrombus:

• Dilated vein, larger than the adjacent artery
• Hypoechoic to anechoic clot — fresh thrombus can be nearly invisible on grayscale, which is why compression, not appearance, makes the diagnosis
• Smooth, central filling defect; a free-floating tail with flow around it is worth its own sentence and a phone call
• Vein completely or nearly completely incompressible

Chronic post-thrombotic change:

• Small, contracted vein with thickened, echogenic walls
• Echogenic, eccentric, wall-adherent material; synechiae or webs
• Partial recanalization with flow channels through the old clot
• Prominent collaterals
• Valvular reflux on augmentation

The honest middle category exists: "echogenic, partially occlusive thrombus, age indeterminate — may represent subacute or chronic disease; comparison with prior imaging recommended." A prior study is worth more than any single feature; if one exists, use it and name the date.

Phasicity: the window into the pelvis

The duplex cannot see the iliac veins or the IVC, but the common femoral waveform reports on them anyway, and this is the part of the exam residents skip in dictation.

• Normal CFV flow is spontaneous and phasic — it varies with respiration.
• A continuous, monophasic CFV waveform means something between the probe and the right atrium is obstructing: iliac vein thrombosis, extrinsic compression (mass, gravid uterus, May–Thurner), or IVC disease.
• The key observation is side-to-side asymmetry: unilateral loss of phasicity is proximal obstruction on that side until proven otherwise, and the report should say "suggests proximal iliac obstruction; recommend CT or MR venography" rather than letting a normal-compression exam read as normal.

Augmentation — a sharp flow surge with calf squeeze — supports patency between the calf and the probe, though it is the least sensitive maneuver and should never overrule a bad waveform.

A related documentation point: on a unilateral exam, the contralateral common femoral waveform is often the only internal control you have. If the lab records it, use it in the report; if the symptomatic side's waveform looks continuous and no comparison exists, say the assessment of proximal obstruction is limited rather than calling it normal by default.

The limited-calf caveat

Many labs scan femoral and popliteal segments only, or attempt the calf and lose it to edema and body habitus. The report must say which exam was actually performed, because the negative predictive value differs:

• A negative complete (whole-leg) exam effectively excludes DVT.
• A negative above-knee exam does not exclude calf DVT — and roughly 15–20% of untreated calf DVTs propagate proximally. The standard safety net is a repeat duplex in 5–7 days in patients with ongoing symptoms and no other explanation, and the report should offer it: "Calf veins not fully evaluated; if clinical suspicion persists, repeat examination in 5–7 days is recommended."

That sentence is the difference between a report that documents an exam and a report that manages a patient.

When it isn't DVT, say what it is

Most venous duplexes are negative, and a negative study on a swollen, painful leg should not end at "no DVT" when the probe has already seen the answer. The non-thrombotic findings worth a sentence:

• Baker's cyst — the single most common alternative explanation for calf pain in this exam. Measure it, and say whether it is simple or shows the ill-defined margins and surrounding edema of a ruptured cyst, which mimics DVT clinically almost perfectly.
• Intramuscular hematoma or a torn medial gastrocnemius — the "tennis leg" the history was pointing at all along.
• Subcutaneous edema — cobblestoning in the superficial soft tissues suggests cellulitis or systemic edema, not venous obstruction, and saying so redirects the workup.
• Enlarged inguinal lymph nodes or a groin mass compressing the vein — occasionally the entire explanation for unilateral swelling with patent veins.

"No DVT. Ruptured Baker's cyst with fluid dissecting along the medial gastrocnemius, likely accounting for symptoms" is a complete consultation. "No DVT" alone sends the patient back to triage with the same leg and no diagnosis.

Superficial thrombophlebitis is not a shrug

Thrombus in the great or small saphenous vein is "superficial," but location changes everything: saphenous thrombus within about 3 cm of the saphenofemoral junction is treated like DVT because of propagation risk. Measure and report the distance from the junction. "Superficial thrombophlebitis of the mid-thigh GSV, with the cephalad extent 2 cm from the saphenofemoral junction" is an anticoagulation decision; "mild superficial clot" is a dismissal.

A model report

EXAMINATION: Venous duplex ultrasound, right lower
extremity
HISTORY: 58-year-old female, right calf swelling, 5 days
post hip arthroplasty.
TECHNIQUE: Grayscale compression, color, and spectral
Doppler from the common femoral through the calf veins.
COMPARISON: None.
FINDINGS:
Common femoral vein: Compressible. Spontaneous, phasic
flow, symmetric with the left. Saphenofemoral junction
patent.
Deep femoral vein (proximal): Compressible.
Femoral vein: Compressible throughout.
Popliteal vein: Noncompressible, distended, with
hypoechoic intraluminal thrombus; no flow on color
Doppler. No free-floating component.
Calf veins: Thrombus extends into one posterior tibial
vein. Peroneal veins compressible.
IMPRESSION:
1. Acute occlusive deep venous thrombosis of the right
   popliteal vein extending into a posterior tibial
   vein.
2. Common femoral through femoral segments patent, with
   normal phasic flow — no evidence of proximal iliac
   obstruction.

Every segment is named with its result, the thrombus has an age and an extent, and the phasicity line quietly clears the pelvis. The normal lower extremity venous duplex template carries this segment structure pre-built, and the rest of the template library does the same for the other bread-and-butter exams. Or dictate a DVT case into the live demo — say "popliteal noncompressible, acute" and watch the full segment-by-segment report, caveats included, assemble around the one positive finding.