The Hidden Lesion

Posted by • June 3rd, 2016

112The repeated occurrences of clots involving the veins in the proximal left leg raise suspicion for the May–Thurner syndrome (compression of the left iliac vein by the overlying right iliac artery).

A 24-year-old woman presented to the ED with pain in the left leg. She had been training for a 5-km race when, 2 days before presentation, she had crampy pain in her left leg, extending to the left lower abdomen and buttock, plus leg swelling and exertional dyspnea. A new Clinical Problem-Solving summarizes.

Clinical Pearl

• What subset of patients with iliofemoral deep-vein thrombosis may benefit from thrombolysis or thrombectomy?

Selected patients with extensive, acute iliofemoral deep-vein thrombosis who have good functional capacity, favorable life expectancy, and a low risk of bleeding may benefit from early thrombus removal in the form of thrombolysis or thrombectomy. These interventions are invasive and carry procedural risks, including hemorrhage, but they also preserve venous valve function. Thus, they may prevent the onset of the post-thrombotic syndrome, a debilitating long-term complication of deep-vein thrombosis that is characterized by leg swelling, claudication, and ulceration due to valvular incompetence and venous outflow obstruction.

Clinical Pearl

• Is thrombophilia testing indicated in patients who present with a first provoked episode of venous thromboembolism?

Thrombophilia testing is not indicated in patients who present with a first, provoked episode of venous thromboembolism, because the risk of recurrent thrombosis is not greatly affected by the presence of a heritable thrombophilia. The American Society of Hematology recommends against routine thrombophilia testing in patients with provoked venous thromboembolism if the thrombotic event can be readily attributed to a transient, major risk factor. For unprovoked venous thromboembolism, guidelines from consensus groups are less clear and often differ.

Morning Report Questions

Q: What are some clinical features of the May–Thurner syndrome?  

A: The May–Thurner syndrome, or the iliac vein compression syndrome, is the most frequently recognized anatomical abnormality that confers a predisposition to deep-vein thrombosis of the proximal left leg. Patients typically present in their third, fourth, or fifth decade, and there is a strong female preponderance, with a 2:1 ratio of affected women to men. Although the left common iliac vein is classically affected, compression of the left external iliac vein, and even compression of the right iliac vein have also been described.

Q: Is the MayThurner syndrome easy to diagnose and how successful are available therapies? 

A: Making the diagnosis of the May–Thurner syndrome requires a high index of suspicion. Intravascular ultrasonography is more sensitive than traditional angiography in detecting venous obstruction and stenosis. Magnetic resonance imaging can be useful, but the degree of stenosis may be difficult to assess once thrombosis and inflammation have occurred. Case series have shown excellent long-term outcomes after combination therapy with catheter-directed thrombolysis, iliac vein stenting, and anticoagulation; recurrent ipsilateral deep-vein thrombosis owing to stent occlusion has been reported to occur in fewer than 15% of adults treated with this approach and can be managed with repeat thrombolysis and stent placement. Anticoagulation therapy is usually continued for 6 months to a year after stenting, to allow for full endothelialization of the stent. Patients in whom the post-thrombotic syndrome develops may be given extended anticoagulation therapy owing to venous stasis.

Figure 3. Pelvic Venograms.

Figure 4. Intravascular Ultrasonography.

3 Responses to “The Hidden Lesion”

  1. elham says:


  2. Krishna says:

    Is there any recommended surgical intervention for its correction rather than stenting?

  3. Anup Katyal says:

    Is there a role of Plavix following iliac stent placement in May Thurner syndrome?