BloodSweatxED
PRN Education · No. 004 · POCUS Series

DVT Compression
Ultrasound.

The whole test is one move: put a vein in the middle of the screen and press until the walls touch. If they touch, no clot at that spot. If they don't, that's a DVT until proven otherwise.

The skill isn't the compression — it's compressing every 1–2 cm through both regions without skipping the spots where clot actually lives.

Source

Curated from the POCUS 101 DVT Ultrasound Made Easy: Step-By-Step Guide. Their labeled vessel-anatomy images and compression clips are the fastest way to lock in the landmarks.

When to scan

And what this exam can't see

Reach for the probe

  • Unilateral leg swelling, pain, or erythema
  • Suspected PE: a positive leg makes the diagnosis (pair with Echo for PE)
  • Moderate/high pretest probability where the formal study is hours away
  • Positive D-dimer needing a same-visit answer

Built-in blind spots

  • The two-region exam skips most of the femoral vein in the thigh — isolated femoral vein DVTs can be missed. Extend your scan or follow up with a formal study when suspicion stays high.
  • Calf DVTs are not the target of this exam.
  • Pelvic/iliac clot is invisible from the leg — a normal exam with a swollen blue leg still needs more imaging.

Setup

Position does half the work

Probe

Linear, high-freq

Vascular/venous preset. Vein in transverse (short axis) — compression is only interpretable in short axis.

Position

Frog leg

Supine, hip externally rotated, knee slightly bent. Reverse Trendelenburg or head of bed up 30°–45° distends the veins and makes everything easier to find.

The rule

Full coaptation

Press until the vein walls completely touch. The artery should just start to deform — that's proof you pushed hard enough.

The scan

Region 1: groin · Region 2: knee
TWO REGIONS · ANTERIOR RIGHT LEG REGION 1 · GROIN CFV → saphenofemoral junction → femoral / deep femoral split REGION 2 · POPLITEAL popliteal vein → calf trifurcation (scan from behind the knee) NORMAL: WALLS COAPT rest compress DVT: VEIN WILL NOT CLOSE rest compress
Fig. 1 — Compress every 1–2 cm through both regions. A vein that will not fully coapt is a DVT until proven otherwise.

Find the common femoral vein

Transverse at the inguinal crease · vein medial to artery

Start at the inguinal ligament. The common femoral vein (CFV) sits medial to the pulsatile common femoral artery. Begin compressing 1–2 cm above the saphenofemoral junction.

Normal: with each compression the vein winks shut completely — anterior and posterior walls in full contact — then springs back.

Work through the junctions

Compress every 1–2 cm · saphenofemoral junction → bifurcation

March distally through the saphenofemoral junction (where the great saphenous dives into the CFV) and on through the CFV's split into the femoral and deep femoral veins, continuing 1–2 cm below the bifurcation.

  • The junction is a clot magnet — be deliberate here
  • Thrombus in the great saphenous at or near the junction behaves like a DVT and generally gets treated like one

Move to the popliteal fossa

Knee bent · probe in the crease · vein superficial to artery

In the popliteal fossa the vein sits on top of (superficial to) the artery — "pop on top." Start at the proximal popliteal vein.

Compress to the trifurcation

Every 1–2 cm · popliteal vein → calf vein confluence

Continue compressions distally until the popliteal vein splits into the calf veins (anterior tibial, posterior tibial, peroneal). That confluence is the end of the exam.

Positive exam: any segment that will not fully coapt under pressure that deforms the artery — with or without visible echogenic clot inside. Fresh clot can be anechoic; non-compressibility alone is the finding.

Calling it

Compressibility is the test
What you seeReadNotes
Full coaptationnormalWalls touch completely at every station in both regions
No coaptationDVTEven with an anechoic lumen — fresh thrombus is often invisible
Soft, deformable fillingacute clotAcute thrombus squishes but won't let walls meet; vein often distended
Rigid, echogenic materiallikely chronicNon-deformable, brightly echogenic, small contracted vein — post-thrombotic change; compare with priors
GSV clot at the junctiontreat seriouslySuperficial vein, but proximity to the CFV changes its behavior

Color Doppler and augmentation are adjuncts, not the test. If compression is equivocal, get the formal study — don't Doppler yourself into confidence.

Pearls & pitfalls

Where this scan goes wrong
Pitfall

The lymph node impostor

An inguinal node in cross-section looks exactly like a vein with clot. Turn the probe: a node is a discrete oval that disappears in long axis; a vessel is a tube that keeps going.

Pitfall

Not pushing hard enough

The most common false positive is timid compression. Your internal check: the artery should visibly start to deform. No arterial deformation, no valid negative.

Pitfall

The femoral vein gap

Two regions leaves the mid-thigh unscanned, and isolated femoral vein DVTs do occur. When pretest probability is high, extend the compressions down the thigh or arrange the formal study.

Pearl

Naming trap: the femoral vein is deep

The vessel formerly called the "superficial femoral vein" is a deep vein. A report of clot there is a DVT that needs treatment — the old name has caused real misses.

Pearl

Compress perpendicular

Angled pressure slides the vein sideways instead of closing it and fakes non-compressibility. Stack the probe straight over the vessel, push straight down.

Pearl

Baker's cyst is a bonus finding

Posterior knee pain with a negative compression exam? Look for the crescent of fluid tracking from the joint — a ruptured Baker's cyst mimics DVT clinically and sits right in your popliteal window.

Sample Epic documentation

Copy · edit · attest

A starting template for the POCUS note. Text in brackets [ ] and pick-lists in { } are fields to complete. Save it as a SmartPhrase, then edit every field to match the actual study.

.pocusDVT
POINT-OF-CARE ULTRASOUND: LOWER EXTREMITY DVT

Indication: {leg swelling / pain : suspected PE} [side ***]
Exam type: Focused / limited, 2-region compression
Operator: @ME@   Interpretation: independent, real-time
Probe: linear

FINDINGS ([right : left] leg)
- Common femoral vein: {fully compressible : non-compressible}
- Saphenofemoral junction / bifurcation: {compressible : non-compressible}
- Popliteal vein to trifurcation: {compressible : non-compressible}
- Echogenic intraluminal thrombus: {none : present [***]}

IMAGE QUALITY: adequate / limited by [***]
Images saved and archived to [PACS / Qpath / ***].

IMPRESSION: {no evidence of proximal DVT in the regions examined :
proximal DVT identified [location ***]}. Limited 2-region study; does
not assess calf or mid-femoral vein segments.

I personally performed and interpreted this study.
Electronically signed: @ME@  @TD@ @NOW@

Sample template only — not a validated institutional SmartPhrase. Verify wording, image-archival, and attestation requirements against your department's POCUS credentialing, coding, and compliance policies before clinical use. Documentation supports, but does not replace, the medical record and QA workflow.

PRN Education · POCUS Series

Keep scanning