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Point-of-care ultrasound for DVT detection

The following tutorial was brought to you by Dr. Leo Smyth, General Internal Medicine physician and ultrasound extra-ordinaire from the University of Calgary.

Deep vein thrombosis is a common clinical conundrum. While clinical features and scoring systems can provide guidance, point-of-care ultrasound can provide immediate information to facilitate decision making at the bedside. This is particularly important when comprehensive imaging is unavailable and you need additional details to begin therapy such as anticoagulation.

In these two tutorials, Dr Smyth unpacks the approach to the detection of DVT with point-of-care ultrasound and how to integrate such findings at the bedside. We have also included a select groups of clips with illustrations to help viewers clearly understand the branch points which need to be imaged for a point-of-care scan.

Part 1: Introduction to DVT ultrasound

Intro to DVT ultrasound at the point-of-care

In this tutorial, Dr Smyth explores the use of point-of-care ultrasound to detect deep vein thrombosis. Below we have highlighted key branch points to further supplement your learning.

DVT Branch points

Key considerations

  • This is commonly performed with a linear or high-frequency probe
  • Ensure compression is perpendicular to the vein
  • Definition of thrombus is at least= non-compressibility
  • Point-of-care DVT exams are primarily compression-based with 2D or B-mode ultrasound
  • Commonly performed more as a rule-in exam (for undifferentiated patients for query PE, unilateral leg edema/pain, and/or pre-procedural vascular access), rather than rule out, which is likely to require a more comprehensive examination

Point 1: common femoral vein

In this first point of compression, the vessels should be acquired with the common femoral vein and artery acquired side by side. Anatomically, the artery should be lateral to the vein. This point of acquisition is quite high in the groin, often above the inguinal fold, so be sure to have adequate exposure. This may require the leg to be externally rotated and abducted.

Point 2: The greater saphenous vein

Below the CFA and CFV is the take-off of the greater saphenous vein. This is a critical junction; a point where thrombus likes to collect.

Point 3: the lateral perforator

Below the greater saphenous vein the lateral perforator vein slips between the birfucation of the common femoral artery (into superficial and deep femoral artery).

Point 4: The Deep Femoral Vein

Here the femoral vein bifurcates; the “superficial” femoral vein (actually a deep vein) continues onto the adductor canal, while the “deep” femoral vein (actually not technically a deep vein) dies in the thigh. Again, another branch point where clots can collect.

Point 5: the popiteal vein

In the popliteal fossa, the popliteal vein is seen. While here the artery and vein are side by side the most common configuration is the popliteal vein on top of the artery (“pop on top”).

Part 2: clinical integration and decision making

Part 2

In this tutorial, Dr Smyth explores how to integrate point-of-care DVT detection into everyday clinical reasoning.

Major limitations & common pitfalls of point-of-care US for DVT detection

  • User-dependent; requires dedicated training
  • Anatomical variation
  • Off-axis or oblique compression
  • Nerves and lymph nodes may falsely resemble a DVT
  • Baker’s cyst in the popliteal fossa
  • Superficial veins confused for deep veins; check to make sure deep veins are paired to an artery
  • Spontaneous echo contrast or rouleaux formation
  • Will not enable detection of pelvic vein DVTs or some femoral vein DVTs below the bifurcation of the femoral vein and deep femoral vein (unless scanned); may be insufficient to rule out DVTs in select patients
  • WIthout use of spectral Doppler and calf augmentation, cannot rule out more proximal DVTs

References

Barrosse-Antle ME, Patel KH, Kramer JA, Baston CM. Point-of-Care Ultrasound for Bedside Diagnosis of Lower Extremity DVT. Chest. 2021;160(5):1853-1863. doi:10.1016/j.chest.2021.07.010

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):538-542. doi:10.1378/chest.10-1479

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. 2019;98(22):e15791. doi:10.1097/MD.0000000000015791

Needleman L, Cronan JJ, Lilly MP, et al. Ultrasound for lower extremity deep venous thrombosis: Multidisciplinary recommendations from the society of radiologists in ultrasound consensus conference. Circulation. 2018;137(14):1505-1515. doi:10.1161/CIRCULATIONAHA.117.03

Zuker-Herman R, Ayalon Dangur I, Berant R, et al. Comparison between two-point and three-point compression ultrasound for the diagnosis of deep vein thrombosis. Journal of Thrombosis and Thrombolysis. 2018;45(1):99-105. doi:10.1007/s11239-017-1595-9

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