Overview
Definition:
May-Thurner stent thrombosis refers to the acute or subacute occlusion of a previously placed endovascular stent in the iliac vein, typically within the context of May-Thurner syndrome (also known as iliac vein compression syndrome)
This syndrome involves compression of the left iliac vein by the overlying right iliac artery, predisposing to deep vein thrombosis (DVT)
Stenting is often used to relieve this compression, and subsequent thrombosis of the stent is a serious complication requiring urgent intervention.
Epidemiology:
May-Thurner syndrome is present in up to 30% of individuals, with a higher prevalence in women
Stent thrombosis is a rare but significant complication of iliac vein stenting, with reported rates varying between 1-5% in the short-to-medium term, depending on stent type, antithrombotic regimen, and patient factors
Risk factors for stent thrombosis include hypercoagulable states, inadequate anticoagulation, undertreatment of May-Thurner syndrome, suboptimal stent deployment, and intimal hyperplasia.
Clinical Significance:
May-Thurner stent thrombosis represents a limb-threatening emergency
It can lead to severe acute venous insufficiency, post-thrombotic syndrome, pulmonary embolism (PE), and in rare cases, venous gangrene
Prompt recognition and effective surgical rescue are critical to restore venous outflow, prevent further complications, and salvage limb viability
This condition is a high-yield topic for DNB and NEET SS examinations due to its complexity and critical management.
Clinical Presentation
Symptoms:
Sudden onset of severe ipsilateral leg swelling
Increasing leg pain and heaviness
Skin discoloration (erythema, cyanosis)
Reduced distal pulses
Fever
Dyspnea or chest pain if associated with PE.
Signs:
Marked unilateral edema of the affected limb
Dilated superficial collateral veins
Tenderness to palpation
Decreased or absent distal pulses (suggesting arterial compromise secondary to venous outflow obstruction)
Signs of shock if massive PE is present.
Diagnostic Criteria:
Diagnosis is suspected clinically in patients with a history of May-Thurner syndrome and iliac vein stenting who present with acute DVT symptoms
Confirmation relies on imaging demonstrating stent occlusion
There are no specific formal diagnostic criteria, but a high index of suspicion combined with imaging is key.
Diagnostic Approach
History Taking:
Detailed history of previous DVT, May-Thurner syndrome diagnosis, prior venous interventions (stenting)
Duration and progression of current symptoms
Current antithrombotic medications and compliance
History of hypercoagulable states
Presence of cardiovascular risk factors
Recent immobility or trauma.
Physical Examination:
Comprehensive lower extremity examination: assess for edema, skin changes (erythema, cyanosis, blistering), temperature, sensation, and motor function
Palpate for tenderness and assess peripheral pulses
Perform a thorough cardiovascular and respiratory examination to rule out PE.
Investigations:
Lower extremity venous Doppler ultrasound: initial modality to assess for DVT and patency of superficial and deep veins, though may be limited in deep pelvic veins
CT venography: gold standard for visualizing iliac veins, stent patency, thrombus burden, and surrounding anatomy
MR venography: alternative to CT venography, especially useful for assessing soft tissues
Angiography: can be diagnostic and therapeutic, allowing for immediate intervention if thrombolysis or angioplasty is planned
Baseline laboratory tests: complete blood count (CBC), coagulation profile (PT/INR, aPTT), renal function tests (creatinine, BUN), electrolytes, D-dimer (may be elevated but not specific for stent thrombosis).
Differential Diagnosis:
Acute deep vein thrombosis in the absence of stenting
Iliac vein compression due to external factors (e.g., tumor, retroperitoneal fibrosis)
Popliteal or femoral venous thrombosis
Acute arterial occlusion
Cellulitis
Lymphedema
Lymphocele or hematoma compressing the vein.
Management
Initial Management:
Immediate anticoagulation with unfractionated heparin (UFH) or low molecular weight heparin (LMWH) to prevent further thrombus propagation and facilitate thrombolysis
Hemodynamic stabilization if patient is in shock
Pain management.
Medical Management:
Systemic thrombolysis: Intravenous infusion of fibrinolytic agents (e.g., alteplase, urokinase) may be considered, but is often less effective for extensive or chronic thrombus within a stent compared to catheter-directed thrombolysis
Anticoagulation: Long-term anticoagulation (e.g., warfarin, direct oral anticoagulants - DOACs) is essential after successful revascularization.
Surgical Management:
Catheter-directed thrombolysis (CDT): Infusion of thrombolytic agents directly into the thrombus via a catheter
Mechanical thrombectomy: Use of devices to physically remove thrombus (e.g., AngioJet)
Pharmacomechanical thrombolysis: Combination of CDT and mechanical thrombectomy
Surgical thrombectomy: Open surgical removal of thrombus, rarely performed for isolated stent thrombosis but may be considered in conjunction with other interventions or if endovascular approaches fail
Stent revision or replacement: If the stent is damaged or inadequate, it may require angioplasty, balloon angioplasty, or stent revision/replacement
IVC filter placement: May be considered in patients with PE or high risk for PE, but should be carefully weighed against increased risk of recurrent thrombosis if filter is placed distal to patent venous segment.
Supportive Care:
Close monitoring of vital signs, limb perfusion, and urine output
Elevation of the affected limb
Graduated compression stockings post-reperfusion to manage post-thrombotic syndrome
Pain control
Physical therapy and early mobilization as tolerated.
Complications
Early Complications:
Re-thrombosis
Bleeding (systemic or at access sites)
Pulmonary embolism
Distal embolization
Vessel dissection or perforation during intervention
Compartment syndrome
Venous gangrene.
Late Complications:
Post-thrombotic syndrome (chronic leg swelling, pain, hyperpigmentation, venous ulcers)
Chronic venous insufficiency
Recurrent venous thrombosis
Stent restenosis or occlusion due to intimal hyperplasia.
Prevention Strategies:
Strict adherence to optimal antithrombotic therapy post-stenting
Thorough pre-procedural assessment for hypercoagulable states
Careful stent selection and deployment to ensure adequate apposition and full coverage of the compressed segment
Follow-up imaging to monitor stent patency
Patient education on compliance with medications and recognition of early symptoms of recurrence.
Prognosis
Factors Affecting Prognosis:
Timeliness of diagnosis and intervention
Extent and duration of thrombosis
Success of revascularization
Underlying cause of May-Thurner syndrome
Presence of comorbidities and hypercoagulable states
Adequacy of long-term anticoagulation.
Outcomes:
With prompt and effective surgical rescue, limb salvage and restoration of venous flow are achievable in most cases
However, many patients develop some degree of post-thrombotic syndrome
Long-term patency rates of revised or redeployed stents vary
Complete resolution of symptoms is not always achieved, and chronic venous insufficiency is common.
Follow Up:
Regular follow-up is essential, including clinical assessment and serial venous ultrasounds or other imaging modalities to monitor stent patency, assess for recurrent thrombosis, and manage post-thrombotic syndrome
Patients require lifelong anticoagulation in many instances and need to be educated about symptom recurrence and lifestyle modifications.
Key Points
Exam Focus:
Recognize May-Thurner stent thrombosis as an emergency requiring urgent intervention
Understand the role of CT venography in diagnosis
Key treatment modalities include pharmacomechanical thrombolysis and stent revision
Differentiate from simple DVT
Emphasize long-term anticoagulation and post-thrombotic syndrome management.
Clinical Pearls:
A sudden increase in leg edema in a patient with prior iliac vein stenting should raise suspicion for stent thrombosis
Do not underestimate the risk of PE
Always consider the underlying May-Thurner anatomy and how it contributed to the initial problem and potential for recurrence.
Common Mistakes:
Delaying intervention due to diagnostic uncertainty
Inadequate anticoagulation post-intervention
Failing to consider distal embolization or PE
Not adequately assessing for underlying hypercoagulable states
Insufficient follow-up of stent patency and management of chronic venous insufficiency.