Endothermal heat-induced thrombosis (EHIT) and post-ablation DVT surveillance/management

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Endovenous thermal ablation carries a risk of endothermal heat-induced thrombosis (EHIT), in which thrombus extends from the treated saphenous vein into the adjacent deep venous system.[@rutherford2018]system [@rutherford2018].

**EHIT Classification:**

* **Class I:** thrombus protrudes into but does not occlude the deep vein
* **Class II:** thrombus occludes the deep vein
* **Class III:** thrombus extends into the common femoral vein or above
* **Class IV:** thrombus extends into the iliac veins or inferior vena cava[@rutherford2018]cava [@rutherford2018]

**Risk Factors:**Factors and Prevention:**

EHIT is more likely with:
* Large great saphenous vein (GSV) diameter (>8–10 mm)
* Higher energy delivery during ablation
* Proximity of the ablation endpoint to the saphenofemoral junction (SFJ)
* Concomitant thrombophilia or hypercoagulable state[@rutherford2018]state [@rutherford2018]

Strategies to reduce the incidence of severe EHIT (Class II–IV) following radiofrequency ablation (RFA) include maintaining an ablation distance of ≥2 cm from the SFJ and the selective use of perioperative prophylactic anticoagulation in high-risk patients [@kedwai2024].

**Surveillance and Management:**

Post-ablation duplex ultrasound should be performed within 1 week to detect EHIT early. Management depends on EHIT class:
* **Class I:** observation with repeat duplex in 1–2 weeks; often resolves spontaneously
* **Class II:** anticoagulation for 3 months; repeat imaging to document resolution
* **Class III–IV:** full therapeutic anticoagulation as for [[deep vein thrombosis (DVT)]]; consider thrombectomy in selected cases[@rutherford2018]cases [@rutherford2018]

True deep vein thrombosis (DVT) (occurring independently of the ablation site) should be treated with standard anticoagulation protocols (see [[venous thromboembolism (VTE)]]) [@esvs2015].