Leg DVT Ultrasound Caitlin Gardiner

The Role of Ultrasound  To exclude deep vein thrombosis as a cause for pain and swelling in the lower limb Screening tool in post operative surgery Known pulmonary embolus, (?location of their embolus) (1)

The Principal of DVT US Non compressibility Filling defects with colour Doppler Focal tenderness (acute thrombus will be hypoechoic and difficult to see on B-mode without increasing gain) Hyperechoic lesion within lumen of the vein

Probe and Pre-set selection Mid frequency linear probe (5-8MHZ) Have access to curvi-linear probe Low PRF (velocity) colour / power / Doppler settings with low wall filter when assessing veins with low velocity flow (2) Select the appropriate vascular setting on the US machine

Patient Set Up Supine, erect or seated in a reclined position to allow access to the groin. Venous distension is useful for assessing calf veins The patient must remove their pants as scanning commences at the groin (2) Important to be conservative and profession. A gown or blanket may be helpful Be conscious that a large amount of the patients are older, post surgery or have limited mobility

Anatomy All images extracted from www.ultrasoundpaedia.com

Common Femoral & (Superficial) Femoral Veins Patient supine with slight external rotation of affected leg In transverse, high in the groin crease, locate the CFA & CFV at the sapheno-femoral junction. Compress the vein. Continue to follow the vein sequentially compressing down to the distal thigh (3)

Popliteal vein Seat the patient on the side of the bed to help dilate the veins for easier visualisation. Place the probe transversely at the knee crease in the popliteal fossa. Compress the popliteal vein throughout the popliteal fossa (3)

Calf Veins Patient still seated on bed Transversely, with the toe of the probe on the medial edge of the mid tibia, locate the paired posterior tibial and peroneal veins Assess their compressibility along their length. Alternatively, in longitudinal, use colour Doppler to confirm their patency (3)

Basic Hard Copy Images A leg DVT series should include the following minimum images: CFV: pre/post compression Proffunda femoris SFV proximal TS: pre/post compression SFV proximal LS: with colour Doppler SFV distal TS: pre/post compression SFV distal LS: with colour Doppler POPV TS: pre/post compression POPV LS: with colour Doppler Posterior tibial veins LS colour Doppler Peroneal veins LS colour Doppler Sapheno-femoral-junction (1)

Differential Diagnosis Common differential diagnoses identifiable on ultrasound are: Bakers cyst (semi-membranosis-gastrocnemial bursa) in the medial popliteal fossa. Superficial venous thrombosis of varices and the long/short saphenous veins. Calf muscle tears (2,3)

Limitations Obese patients, or those with severe oedema Patients with open wounds/sutures/bandages Patients with a low pain threshold (2)

Thank you

References (1) ASUM, 2007. Short Syllabus, DVT. www.asum.com.au (2) Rumack C, Wilson R, Charboneau W and Levine D, 2010. Diagnostic Ultrasound 2-Volume Set, 4th Edition. Mosby. (3) Thrush A and Hartshorne T, 2009. Vascular Ultrasound: How, Why and When, 3e. Churchhill Livingstone. (4) Weinberg I, 2012. DVT Ultrasound Protocol. Vascular Medicine. www.angiologist.com