POCUS masterclass · DVT & vascular
Squeeze the vein.
If the walls do not meet, the leg has a clot until proven otherwise.
Compression ultrasound (CUS) answers one binary question: does this vein collapse completely under gentle probe pressure?
- Full coaptation (the walls touch) means there is no thrombus at that point.
- A non-compressible vein means thrombus (acute or chronic) until proven otherwise. Echogenic material helps, but is not required.
Why it matters to us: postoperative and ICU patients are at high VTE risk. In the hypotensive or hypoxic patient, a non-compressible proximal vein plus a dilated RV changes the working diagnosis in minutes, at the bedside.
In this tutorial
- 01–02 · Framework · set-up
- Part I · Vein vs artery · landmarks · protocols
- Part II · Evidence · pitfalls · ICU and PE
- Part III · Three patients
- Quiz · references · close
All images on this page are schematics and simulations, not real scans.
Choose the examination and report its coverage.
Start with pre-test probability. Choose a defined compression examination and plan the next step if it is limited or negative.
- 1IndicationWhat is the clinical question? Swollen leg? Unexplained hypoxia or shock with RV dilatation? A local protocol for high-risk delayed hip-fracture surgery? (Routine screening of asymptomatic patients is not recommended by CHEST, and sensitivity is lower without symptoms.) Would the answer change management? If not, do not scan.
- 2AcquisitionLinear probe, correct position, transverse views, compress at every landmark (and every 1–2 cm between landmarks if doing a continuous scan).
- 3InterpretationCompressible, non-compressible or inconclusive at each segment. Report the segment, not just "DVT yes/no".
- 4Medical decision-makingCombine with pre-test probability (Wells), D-dimer and the rest of the POCUS picture (RV, lungs). Treat, rescan in about 1 week, or refer for formal whole-leg duplex. Wells is validated in outpatients only: in inpatients and post-op/ICU patients use clinical gestalt, and a negative limited scan with ongoing suspicion needs an extended or whole-leg scan, or a repeat.
| Segment | Right | Left |
|---|---|---|
| CFV at inguinal ligament | Compressible | Compressible |
| SFJ | Compressible | Compressible |
| CFV bifurcation | Compressible | Compressible |
| FV mid-thigh | Not scanned | Not scanned |
| Popliteal to trifurcation | Compressible | Inconclusive (positioning) |
| Calf veins | Not scanned | Not scanned |
Set up for success before you touch the leg.
High-frequency linear (roughly 5–12 MHz). Start depth about 4 cm; increase as needed. In obese or oedematous thighs, switch to a curvilinear (2–5 MHz) probe for the femoral vein, accepting lower resolution.
Venous or vascular preset if available. Set the gain so the normal lumen is black.
Transverse (short-axis) for compression. Probe marker to the patient's right, as for other transverse views. Posterior views (popliteal fossa, calf) keep the same rule, so on the right leg lateral is on screen left and medial on screen right; on the left leg this flips. Longitudinal views are for Doppler and for following a thrombus tail, not for compression.
Screen in line with your eye and the leg. The non-scanning hand can provide counter-pressure behind the thigh at the adductor canal.
Find the pair.
At every level, identify the artery first, then its companion vein. Then squeeze until the walls meet, or the artery starts to give.
Linear probe · Transverse · Compress · Move 1–2 cm · Repeat
Five tells. Then squeeze.
| Feature | Vein | Artery |
|---|---|---|
| Compress | Collapses fully with gentle pressure | Deforms only with much firmer pressure |
| Wall | Thin, barely visible | Thick, bright, three-layered |
| Shape | Oval, larger, changes with respiration or Valsalva | Round, constant |
| Pulse | Non-pulsatile (may transmit adjacent pulsation) | Pulsatile, expands with systole |
| Doppler | Low-velocity, phasic with respiration; augments with calf squeeze | Pulsatile, high-velocity; triphasic in a normal limb at rest |
| ICU caveat | Pulsatile CFV flow suggests raised right-sided pressure or TR: do not mistake the vein for the artery, compress it. Compare CFV Doppler with the other side: unilateral loss of phasicity suggests proximal (iliac/IVC) obstruction; bilateral loss may be central or due to positive-pressure ventilation. | |
Groin, medial to lateral: vein, artery, nerve (NAVEL from lateral: Nerve, Artery, Vein, Empty space, Lymphatics). The CFV lies medial to the CFA. Popliteal fossa, scanned from behind: the vein is superficial to the artery.
Groin to knee: the five places to squeeze.
Follow the vein from the inguinal ligament downwards, compressing at each level. Tap a level to see it.
- 1Common femoral vein (CFV)Just below the inguinal ligament, medial to the CFA.
- 2Saphenofemoral junction (SFJ)The great saphenous vein (GSV) joins the CFV anteromedially: the "Mickey Mouse" sign (the CFV is the face; the CFA and GSV are the ears). ESVS 2021 advises therapeutic anticoagulation for about 3 months, as for DVT, when GSV thrombus is within 3 cm of the SFJ; refer for formal duplex.
- 3CFV bifurcationA few centimetres below: the femoral vein (FV) and the deep femoral (profunda) vein, which dives posterolaterally. Compress just above and just below.
- 4Femoral vein, mid-thigh to adductor canalDeep to the femoral artery under sartorius. In the adductor (Hunter's) canal it is deep and hard to compress: use counter-pressure behind the thigh, or a curvilinear probe.
- 5Popliteal vein (PV)Superficial to the artery, from the top of the fossa down to the trifurcation (anterior tibial vein and tibioperoneal trunk; the trunk receives the posterior tibial and peroneal veins).
2-point, 3-point, whole-leg: what each one actually covers.
Definitions vary between papers. State the one you used.
Point 1: CFV from the inguinal ligament through the SFJ to the femoral/deep femoral bifurcation. Point 2: popliteal vein from the popliteal crease (or upper fossa) to the trifurcation. Misses: femoral vein of the mid and distal thigh, iliac veins, calf veins.
Adds the femoral vein in the mid-thigh (most commonly CFV/SFJ, FV mid-thigh, popliteal). Some authors use "3-point" to mean CFV, SFJ and popliteal: check the source. Pooled ED data show similar accuracy to 2-point (Lee 2019), but because isolated femoral-vein clots exist (Adhikari 2015), adding the mid-thigh FV costs little and closes a known gap.
Continuous compression every 1–2 cm from the inguinal ligament to the trifurcation, including the first few cm of the deep femoral vein. The most complete proximal scan achievable at the bedside.
Proximal veins plus the calf veins (posterior tibial, peroneal, often muscular veins), usually with colour Doppler. Normally a formal vascular-lab study; detects isolated calf DVT.
| Segment | 2-pt | 3-pt | Ext. | WLUS |
|---|---|---|---|---|
| CFV · SFJ · bifurcation | ✓ | ✓ | ✓ | ✓ |
| FV mid-thigh | – | ✓ | ✓ | ✓ |
| FV adductor canal | – | – | ✓ | ✓ |
| Deep femoral vein (first few cm) | origin | origin | ✓ | ✓ origin |
| Popliteal to trifurcation | ✓ | ✓ | ✓ | ✓ |
| Calf veins | – | – | – | ✓ |
| Iliac veins · IVC | – | – | – | – |
Walk the leg. Where does each protocol look?
Most proximal DVTs involve the CFV or popliteal vein, which is why 2-point scanning works most of the time. A minority are isolated outside the two points (for example the mid-thigh femoral vein or the deep femoral vein): in one ED cohort, about 6% of DVTs were isolated to the femoral vein (5.5%) or deep femoral vein (0.8%), so 2-point scanning would have missed them (Adhikari 2015, single-centre, retrospective). Isolated calf DVT is not detected by any limited proximal protocol.
How to compress properly.
- Transverse only for compression. In long axis the probe slides off the vein and it can look compressed when it is not.
- Straight down, perpendicular to the vessel, enough to collapse the vein and slightly deform the artery. Hold for a second, release, move 1–2 cm, repeat.
- Full coaptation means the anterior and posterior walls touch along their whole width. Partial collapse is abnormal.
- Keep the vein centred. If it slides sideways out of the beam as you push, it has not been tested. Angle slightly or reposition.
- Freeze cines or split-screen "no compression | compression" images at each level for documentation.
- Free-floating thrombus at the proximal tip: if you see a mobile clot, use gentle pressure only, document, and do not repeatedly compress.
- Colour Doppler is an adjunct: filling defects, absent flow, absent augmentation. Do not use it to override a clearly non-compressible vein, and do not call a vein patent on colour alone if it does not compress.
Know your gaps.
A non-compressible vein rules DVT in. A compressible vein rules out clot only where you put the probe.
What the evidence supports, and its limits.
Emergency-physician CUS, meta-analysis (Pomero 2013; 16 mostly small studies, variable training and quality): pooled sensitivity about 96% and specificity about 97% against formal duplex for proximal DVT. Intensivist-performed CUS is also accurate (Kory 2011). Lee 2019 meta-analysis: 2-point and 3-point performed similarly (pooled sensitivity about 90% for each, specificity 95–98%). Confidence intervals were wide, and sensitivity was higher when an attending performed the scan and with DVT-specific training.
Serial 2-point CUS plus D-dimer was equivalent to a single whole-leg colour Doppler study for 3-month VTE (Bernardi, JAMA 2008: roughly 0.9% vs 1.2%). After a single negative whole-leg study, 3-month VTE risk is about 0.6% (Johnson, JAMA 2010). ACCP 2012 and ASH 2018 accept either serial proximal CUS (repeat at about 1 week) or a single whole-leg study, combined with pre-test probability and D-dimer. The SRU 2018 consensus favours complete duplex (whole-leg, with bilateral CFV Doppler) as the standard diagnostic test. If only a limited (proximal, compression-only) scan is done and is negative, SRU recommends a second study, ideally a complete duplex, in 5–7 days.
Not seen on proximal protocols. A minority propagate proximally (often quoted around 10–15%; estimates vary), mostly within 2 weeks. CHEST 2016, reaffirmed in the 2021 update: if not anticoagulated, serial imaging over 2 weeks; anticoagulate if severe symptoms or risk factors for extension, and anticoagulate if the thrombus extends (recommended if it extends proximally). CACTUS (Righini 2016): no significant benefit of LMWH in low-risk outpatients with calf DVT, but more bleeding.
Limits: evidence is mostly from symptomatic outpatients. Performance in ICU, post-op and asymptomatic screening populations is less well defined. Operator training matters.
Things that look like clot, and clot that looks like nothing.
Inadequate pressure
The commonest cause. The artery has not deformed. Push more, use counter-pressure, re-centre.
Lymph nodes in the groin
Oval, hypoechoic cortex with a bright echogenic hilum. They do not continue as a tube when you slide the probe up and down; no paired artery; hilar flow only on colour.
Baker (popliteal) cyst
Anechoic, posteromedial, between the medial head of gastrocnemius and the semimembranosus tendon, often with a "neck" toward the joint; no Doppler flow. The popliteal vein is separate and compressible beside its artery. A ruptured cyst can mimic DVT clinically, and the two can coexist.
Haematoma, abscess, muscle tear
Not tubular, not paired with an artery.
Chronic post-thrombotic change (not necessarily acute DVT)
Real thrombus, but old: thick wall, bright synechiae, partial compressibility, often a small vein. Compare with any prior scan before calling it new.
Acute anechoic thrombus
Fresh clot can be as black as blood. Only compression reveals it. The vein is often distended.
Duplicated femoral vein
A common variant (estimates range widely, from about 1 in 10 to more than 1 in 3 limbs, depending on definition). One limb of the pair may be thrombosed while the other compresses. Look for two veins around the femoral artery.
Obese or oedematous limb
Inadequate penetration and compression at the adductor canal. Switch to curvilinear, use counter-pressure, or call it inconclusive.
Wrong popliteal position
A fully extended or hyperextended knee flattens the vein. Scan with the knee flexed 20–30°.
Protocol gaps · iliac and IVC thrombus
Mid-thigh FV, deep femoral, iliac and calf veins are outside limited protocols. With iliac or IVC clot the CFV compresses, but its Doppler loses respiratory phasicity and augmentation.
Spot the impostor.
Five deliberately tricky views, plus a bonus. For each, decide: normal vein, DVT, or mimic / inconclusive. Then compress and reveal.
The leg in the hypoxic, hypotensive patient.
ESC 2019: finding a proximal DVT on CUS in a patient with suspected PE is sufficient to justify anticoagulation without further imaging in many cases. A proximal DVT is found in roughly 30–50% of patients with PE, so a negative CUS does not exclude PE.
In suspected high-risk PE with shock, bedside echo is the key test: if CTPA is not immediately feasible, RV dysfunction on echo is enough to justify reperfusion therapy. A non-compressible proximal vein adds weight. Multiorgan POCUS (heart, lungs, leg veins) improved diagnostic accuracy for PE in an emergency department study (Nazerian 2014).
Terminology: the 2026 AHA/ACC guideline replaces "massive/submassive" with clinical categories A–E. Category E (cardiopulmonary failure) is PE with haemodynamic instability, from persistent hypotension or shock through to cardiac arrest. For category E the guideline treats systemic thrombolysis, catheter-based therapy and surgical embolectomy as reasonable options for selected patients, and it recommends PE response teams. This corresponds broadly to ESC 2019 "high risk" (cardiac arrest, obstructive shock or persistent hypotension).
Aorta plus leg veins. Aorta: an outer-wall-to-outer-wall diameter of 3 cm or more is an aneurysm; look for a dissection flap (covered at the shock station). A non-compressible CFV or popliteal vein in an undifferentiated shocked patient points toward obstructive shock from PE.
- Post-op day 2–10 sudden hypoxia or tachycardia, especially after major orthopaedic, pelvic, abdominal or cancer surgery.
- Symptomatic leg, or a local protocol for high-risk delayed hip-fracture surgery (routine screening of asymptomatic patients is not recommended by CHEST): a pre-op DVT changes anticoagulation, regional anaesthesia timing and IVC filter discussions.
- ICU patients with femoral CVCs: catheter-related thrombosis is common; scan around the catheter (compression may be limited by the line).
- Upper limb (CVCs, PICCs): compress the internal jugular, axillary and brachial veins as for the leg. The subclavian vein cannot be compressed behind the clavicle, so use colour and Doppler there (loss of respiratory variation suggests central obstruction).
The same vein–artery identification skills underpin US-guided femoral and peripheral access: vascular access.
- RV dilated: basal RV/LV diameter ratio ≥ 1.0 in apical 4-chamber (ESC 2019).
- Septal flattening, "D-shaped" LV in parasternal short axis.
- McConnell sign (RV free-wall hypokinesis with apical sparing), TAPSE < 17 mm (Lang 2015; ASE right heart guideline 2025; ESC 2019 uses < 16 mm), plethoric IVC.
- A mobile right-heart thrombus (clot in transit) is a high-risk finding: treat urgently.
- Lungs (lung station): often an A-line pattern with sliding. Hypoxia with dry lungs and a big RV should make you think of PE. PE may also show small peripheral subpleural consolidations (infarcts), typically posterobasal: an A-line profile is supportive but not required.
- RV free wall thin (< 5 mm) in acute PE; a thick RV wall suggests chronic pulmonary hypertension.
Three patients.
Read the vignette, then reveal the assessment, scan findings and management discussion in stages. Commit to an answer before each reveal.
Indication · Acquisition · Interpretation · Medical decision
Teaching vignettes. All images are schematic simulations, not real scans.
Eight questions before we finish.
Tap an answer.
Where the numbers come from.
- Needleman L, Cronan JJ, Lilly MP, Merli GJ, Adhikari S, Hertzberg BS, et al. Ultrasound for lower extremity deep venous thrombosis: multidisciplinary recommendations from the Society of Radiologists in Ultrasound Consensus Conference. Circulation. 2018;137(14):1505–15. doi:10.1161/CIRCULATIONAHA.117.030687
- Bernardi E, Camporese G, Büller HR, Siragusa S, Imberti D, Berchio A, et al. Serial 2-point ultrasonography plus D-dimer vs whole-leg color-coded Doppler ultrasonography for diagnosing suspected symptomatic deep vein thrombosis: a randomized controlled trial. JAMA. 2008;300(14):1653–9. doi:10.1001/jama.300.14.1653
- Johnson SA, Stevens SM, Woller SC, Lake E, Donadini M, Cheng J, et al. Risk of deep vein thrombosis following a single negative whole-leg compression ultrasound: a systematic review and meta-analysis. JAMA. 2010;303(5):438–45. doi:10.1001/jama.2010.43
- Pomero F, Dentali F, Borretta V, Bonzini M, Melchio R, Douketis JD, et al. Accuracy of emergency physician-performed ultrasonography in the diagnosis of deep-vein thrombosis: a systematic review and meta-analysis. Thromb Haemost. 2013;109(1):137–45. doi:10.1160/TH12-07-0473
- Lee JH, Lee SH, Yun SJ. Comparison of 2-point and 3-point point-of-care ultrasound techniques for deep vein thrombosis at the emergency department: a meta-analysis. Medicine (Baltimore). 2019;98(22):e15791. doi:10.1097/MD.0000000000015791
- Kory PD, Pellecchia CM, Shiloh AL, Mayo PH, DiBello C, Koenig S. Accuracy of ultrasonography performed by critical care physicians for the diagnosis of DVT. Chest. 2011;139(3):538–42. doi:10.1378/chest.10-1479
- Adhikari S, Zeger W, Thom C, Fields JM. Isolated deep venous thrombosis: implications for 2-point compression ultrasonography of the lower extremity. Ann Emerg Med. 2015;66(3):262–6. doi:10.1016/j.annemergmed.2014.10.032
- Zitek T, Baydoun J, Yepez S, Forred W, Slattery DE. Mistakes and pitfalls associated with two-point compression ultrasound for deep vein thrombosis. West J Emerg Med. 2016;17(2):201–8. doi:10.5811/westjem.2016.1.29335
- Bates SM, Jaeschke R, Stevens SM, Goodacre S, Wells PS, Stevenson MD, et al. Diagnosis of DVT: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(2 Suppl):e351S–e418S. doi:10.1378/chest.11-2299
- Lim W, Le Gal G, Bates SM, Righini M, Haramati LB, Lang E, et al. American Society of Hematology 2018 guidelines for management of venous thromboembolism: diagnosis of venous thromboembolism. Blood Adv. 2018;2(22):3226–56. doi:10.1182/bloodadvances.2018024828
- Kearon C, Akl EA, Ornelas J, Blaivas A, Jimenez D, Bounameaux H, et al. Antithrombotic therapy for VTE disease: CHEST guideline and expert panel report. Chest. 2016;149(2):315–52. doi:10.1016/j.chest.2015.11.026
- Stevens SM, Woller SC, Baumann Kreuziger L, Bounameaux H, Doerschug K, Geersing GJ, et al. Antithrombotic therapy for VTE disease: second update of the CHEST guideline and expert panel report. Chest. 2021;160(6):e545–e608. doi:10.1016/j.chest.2021.07.055
- Righini M, Galanaud JP, Guenneguez H, et al. Anticoagulant therapy for symptomatic calf deep vein thrombosis (CACTUS): a randomised, double-blind, placebo-controlled trial. Lancet Haematol. 2016;3(12):e556–62. doi:10.1016/S2352-3026(16)30131-4
- Wells PS, Anderson DR, Rodger M, Forgie M, Kearon C, Dreyer J, et al. Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. N Engl J Med. 2003;349(13):1227–35. doi:10.1056/NEJMoa023153
- Kakkos SK, Gohel M, Baekgaard N, Bauersachs R, Bellmunt-Montoya S, Black SA, et al. European Society for Vascular Surgery (ESVS) 2021 clinical practice guidelines on the management of venous thrombosis. Eur J Vasc Endovasc Surg. 2021;61(1):9–82. doi:10.1016/j.ejvs.2020.09.023
- Konstantinides SV, Meyer G, Becattini C, Bueno H, Geersing GJ, Harjola VP, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS). Eur Heart J. 2020;41(4):543–603. doi:10.1093/eurheartj/ehz405
- Creager MA, Barnes GD, Giri J, et al. 2026 AHA/ACC/ACCP/ACEP/CHEST/SCAI/SHM/SIR/SVM/SVN guideline for the evaluation and management of acute pulmonary embolism in adults: a report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2026;153:e977–e1051. doi:10.1161/CIR.0000000000001415
- Nazerian P, Vanni S, Volpicelli G, Gigli C, Zanobetti M, Bartolucci M, et al. Accuracy of point-of-care multiorgan ultrasonography for the diagnosis of pulmonary embolism. Chest. 2014;145(5):950–7. doi:10.1378/chest.13-1087
- Perera P, Mailhot T, Riley D, Mandavia D. The RUSH exam: Rapid Ultrasound in SHock in the evaluation of the critically ill. Emerg Med Clin North Am. 2010;28(1):29–56. doi:10.1016/j.emc.2009.09.010
- Via G, Hussain A, Wells M, Reardon R, ElBarbary M, Noble VE, et al. International evidence-based recommendations for focused cardiac ultrasound. J Am Soc Echocardiogr. 2014;27(7):683.e1–683.e33. doi:10.1016/j.echo.2014.05.001
- American College of Emergency Physicians. Ultrasound guidelines: emergency, point-of-care, and clinical ultrasound guidelines in medicine [policy statement, revised April 2023]. Irving (TX): ACEP; 2023. acep.org
Simulations are teaching schematics, not diagnostic images. Anatomy, echogenicity and compression thresholds are simplified. Clot-location weights in the "Walk the leg" simulation are illustrative, not epidemiological. Protocol definitions vary between studies.
Squeeze, report the segment, know your gaps.
- Linear probe, transverse, compress until the walls meet. The artery deforms first if you are pushing hard enough.
- A non-compressible vein means thrombus (acute or chronic); correlate with history and any prior scan. Echogenicity is a bonus, not a requirement.
- 2-point covers CFV/SFJ and popliteal; 3-point adds the mid-thigh femoral vein. Neither sees calf or iliac veins.
- Negative limited scan plus a positive D-dimer or high pre-test probability: repeat in about a week or arrange a whole-leg study.
- In the shocked or hypoxic patient, combine legs with heart and lungs: a big RV, dry lungs and clot in the leg mean PE until proven otherwise.