Teaching Case

Middle-aged female patient with unremarkable past medical history suffered from left-sided groyne pain, tenderness and swelling three days after endovenous laser ablation of the ipsilateral small saphenous vein. Vital signs were stable.
Laboratory assays revealed elevated plasma D-Dimer (1095 ng/mL), fibrinogen (555 mg/dL) and C-reactive protein (131 mg/L).

Following colour Doppler ultrasound (not shown) detection of occlusive left femoral vein thrombosis, multidetector CT (Fig.1) panoramically showed the full extent of acute thrombotic changes to the ipsilateral inferior hypogastric and obturator veins, causing compression of the urinary bladder: the involved vessels appeared mildly dilated, with luminal non-opacification and prominent enhancement of venous walls, consistent with a diagnosis of endovenous heat-induced thrombosis.
Anticoagulation with low-molecular-weight heparin was started and screening for hypercoagulable states yielded normal results. Repeated CT a week later (Fig.2) showed persistent thrombosis of proximal femoral and obturator veins with disappeared mural enhancement and increased mass effect on the bladder.
Ultimately the patient did well, and follow-up CT three months later (Fig.3) showed recanalisation of the left femoral vein, persistence of chronic obturator vein thrombosis.

If untreated, lower-extremity venous insufficiency (LEVI) may lead to complications such as thrombophlebitis, bleeding, lipodermosclerosis and stasis ulcers. Surgical high ligation and stripping represented the traditional treatment of symptomatic varicose veins. During the last decade, minimally invasive percutaneous therapies such as endovenous laser ablation (ELA) gained high acceptance and are recommended as first-line treatment by current international guidelines [1-5]. Recently, ELA is being performed in patients with superficial venous thrombosis, to treat the underlying LEVI, avoid risk of thromboembolism and obviate the need for anticoagulation [6].
ELA achieves venous obliteration by heat-induced irreversible damage to the vein lining, followed by fibrotic sealing of the lumen. During the procedure, the incompetent vein is punctured in the reverse Trendelenburg position, then the laser fiber is introduced, advanced and then pulled back during energy administration [1-5].
Performed in outpatients under local anaesthesia, ELA has high (over 90%) early and long-term success rates, and allows an early return to normal activities. The majority of adverse events are minor and self-limiting, such as ecchymosis, discomfort, bruising and swelling at the access site, distal paraesthesias or hypoesthesia. However, major complications are reported after up to 10% of procedures, including skin burns, nerve injury and endovenous heat-induced thrombosis (EHIT). The latter represents the most feared complication, refers to thrombus extending into a deep vein within 72 hours after superficial venous thermoablation, and occurs in 2.8-7.7% of patients with occasional mortality due to pulmonary embolism. Risk factors include advanced age, female gender and history of superficial or deep thrombophlebitis [1, 4, 5, 7-11].
EHIT may be detected by systematic post-procedural use of colour Doppler ultrasound, and should be promptly suspected when the patient develops symptoms or signs consistent with venous thromboembolism in the ipsilateral leg proximal to the treated saphenous vein. Although most instances are initially diagnosed, as in this patient contrast-enhanced multidetector CT allows for a comprehensive evaluation of EHIT proximal extension, which is categorised as grade 1 (thrombosis below the saphenous-femoral junction), 2, 3 and 4 respectively corresponding to thrombus occupying <50%, >50% or occluding the femoral vein diameter. CT findings recall those of septic thrombophlebitis, including variable degrees of venous enlargement, luminal non-opacification, sometimes associated with mural hyperenhancement and perivascular fat stranding [12].
With prompt diagnosis and treatment, the prognosis of EHIT is good. Whereas grade 2 EHIT is generally treated with anti-thrombotic prophylaxis, grades 3 and 4 warrant full-dose anticoagulation [7-9].