Two-Point vs. Full Compression Protocol
Two-point compression: Assesses only the CFV at the groin and popliteal vein. Fast (5-10 minutes), sensitivity >95% for proximal DVT, but misses isolated calf DVT.
Full compression: Assesses every accessible deep vein segment. Takes 15-25 minutes. Most outpatient vein practices should perform the full protocol.
Compression Technique
Use a high-frequency linear probe (7-14 MHz). Apply firm, steady pressure in transverse orientation. A normal vein collapses completely. A thrombosed vein does not compress or compresses only partially. Scan from the CFV to the popliteal vein, compressing every 1-2cm.
DVT Screening Settings by Machine
- MX7: L12-3s, depth 3-5cm superficial, 5-8cm popliteal.
- M8 Elite: Same probe strategy. iClear for tissue-thrombus differentiation.
- Resona i9T: L14-3WU. ZST+ penetration without sacrificing resolution.
- Consona N9: Linear probe, vascular preset, depth adjusted per segment.
Color Doppler Confirmation
After compression, use color Doppler to confirm flow. Augment with distal calf squeeze. Absence of color flow in a non-compressible segment confirms acute thrombosis.
Acute vs. Chronic DVT
- Acute thrombus: Anechoic or hypoechoic, vein is distended, may be partially free-floating.
- Chronic thrombus: Echogenic, vein may be contracted, often recanalization with partial color flow.
Frequently Asked Questions
Full vs. two-point compression?
Full protocol for initial workup. Two-point for serial follow-up after a negative initial exam.
Which probe for calf vein assessment?
Start with linear at 7-10 MHz. Switch to curvilinear at 3-5 MHz for large or edematous calves.
Should I check for DVT before vein procedures?
Yes. Most practices perform a focused deep vein assessment pre-procedure.
How should DVT findings be documented?
Report each segment as compressible, non-compressible, or partially compressible.