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Indications / Contraindications
Indications for IR Intervention
- Acute SMV thrombosis with radiologic evidence of ischemia (bowel wall thickening, pneumatosis, portal venous gas)
- SMV/portal vein thrombosis not responding to anticoagulation alone within 24–48h of initiation
- Subacute SMV thrombosis (<2 weeks) with worsening clinical picture despite anticoagulation
- Contraindication to systemic anticoagulation with active SMV thrombosis — CDT may treat local thrombus
- Post-operative SMV thrombosis after hepatectomy, Whipple, or bariatric surgery — evaluate urgently
Note: Most acute SMV thrombosis is managed with anticoagulation alone. IR intervention (CDT) is reserved for patients who fail anticoagulation or have high-risk features. Always discuss with surgery team.
Absolute Contraindications to IR CDT
- Bowel perforation or frank peritonitis — surgical emergency, not IR
- Hemodynamic instability requiring OR — go to surgery
- Irreversible bowel infarction (pneumoperitoneum, septic shock, lactate >10 mmol/L despite resuscitation)
Relative Contraindications to Lysis
- Recent surgery (<10 days) — increased hemorrhagic risk
- Active GI bleeding
- Prior stroke (<3 months) or known intracranial mass
- Severe thrombocytopenia (platelets <50K)
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Pre-Procedure Checklist
CT abdomen/pelvis with portal venous contrast phase: document thrombus extent (SMV, portal vein, splenic vein, IVC involvement), bowel wall changes (edema, pneumatosis, portal venous gas — these indicate worsening ischemia), ascites
Surgical consultation: concurrent surgical evaluation mandatory before IR intervention — IR cannot replace surgery if bowel is infarcted
Resuscitation: IV fluids (avoid over-resuscitation), NPO, NGT decompression, broad-spectrum IV antibiotics (pip-tazo or carbapenem)
Anticoagulation: Start UFH 80 units/kg bolus + 18 units/kg/h — do not wait for IR if anticoagulation not contraindicated
Labs: CBC, CMP, lactate (elevated = ischemia/infarct), INR, fibrinogen, lipase (assess pancreatic involvement)
Consent: intraperitoneal hemorrhage from transhepatic access, ICH from lysis, bowel perforation (if ischemia already advanced), hepatic tract hemorrhage, need for emergent surgery despite successful lysis
Draw hypercoagulable studies before anticoagulation if possible: Factor V Leiden, prothrombin mutation, antiphospholipid Ab, AT-III, Protein C/S, JAK2 V617F, PNH screen
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Relevant Anatomy
Mesenteric Venous Anatomy
- Superior mesenteric vein (SMV): receives drainage from small bowel and right colon → runs to the right of the SMA → joins splenic vein to form portal vein at pancreatic neck (L1–L2)
- Portal vein: formed at confluence of SMV + splenic vein → enters hepatic hilum; thrombus commonly propagates from SMV into the portal vein
- Thrombus distribution: SMV thrombosis commonly extends into portal vein; less commonly extends into superior portal vein branches or intrahepatic portal veins
Access Anatomy for CDT
- Transjugular (TIPS access): right IJV → TIPS needle from hepatic vein into portal vein → lysis catheter placed into SMV; lower bleeding risk than transhepatic; preferred when coagulopathy or ascites present; TIPS simultaneously provides portal outflow to reduce rethrombosis risk
- Transhepatic access: segment 5 or 6 portal vein branch → advance catheter retrograde through portal vein into SMV thrombus; direct and technically faster; increased hemorrhage risk with ascites/coagulopathy; limit sheath size to ≤7 Fr
- Transsplenic (last resort): splenic vein → portal vein → SMV; highest splenic hemorrhage risk; use only when both transjugular and transhepatic access fail or are anatomically not feasible
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Technique
Default RadCall approach · share your own below
Supplies
Ultrasound machine (for transhepatic portal vein access)
21G Chiba needle
0.018″ → 0.035″ wire system
7–9 Fr vascular sheath
Multi-sidehole infusion catheter (UniFuse or Cragg-McNamara)
rtPA (alteplase): 1 mg/h infusion
Pressure measurement manifold
Gelfoam for tract embolization
Steps — Transhepatic CDT
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Transhepatic Portal Vein Access
Same technique as portal vein stenting. US-guided right portal vein branch access (segment 5 or 6), 21G needle → 0.035″ wire → 7–9 Fr sheath.
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Portal Venogram
Inject to visualize thrombus in portal vein and proximal SMV. Assess thrombus extent and residual flow.
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Navigate to SMV Thrombus
Advance angled catheter + Glidewire retrograde from portal vein into SMV. Cross thrombus to reach patent SMV distally. Confirm position with injection.
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Place Infusion Catheter
Advance multi-sidehole infusion catheter to span thrombus: tip in patent SMV distal to thrombus, side holes throughout thrombus, proximal end in portal vein.
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Begin rtPA Infusion
1 mg/h through infusion catheter. Systemic heparin 300–500 units/h peripherally via separate IV access. Monitor fibrinogen q6h; hold if <100 mg/dL.
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Check Venogram at 12–24h
Return to IR. Inject through catheter. If >50% thrombus reduction: continue or withdraw. If minimal response at 24h: mechanical thrombectomy adjunct (AngioJet) or accept failure and continue anticoagulation.
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Catheter Removal + Tract Embolization (Critical)
When adequate lysis achieved or 24h passed: withdraw catheter. Embolize transhepatic tract with Gelfoam on withdrawal. This step is critical — prevents post-procedure hemorrhage while patient is fully anticoagulated.
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Transition to Systemic Anticoagulation
Immediately after catheter removal: resume/initiate therapeutic systemic anticoagulation. LMWH bridge to warfarin (INR 2–3) or DOAC per hematology recommendation.
Mechanical Adjuncts
AngioJet PMT through portal vein access for rapid debulking. Aspiration catheters less effective given tortuous portal/SMV anatomy. Use mechanical devices only if facilities and trained staff available.
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Troubleshooting
Problem
Worsening clinical status during lysis (increasing abdominal pain, lactate rising)
Likely cause: Bowel ischemia progressing, lysis inadequate, complication of procedure
Next step: STOP lysis immediately. Emergent surgical consultation. CT abdomen if patient hemodynamically stable. Lysis cannot reverse established bowel infarction — surgery is required for any clinical deterioration during CDT.
Problem
Significant intraperitoneal hemorrhage post-access
Likely cause: Hepatic parenchymal tract bleeding, portal branch avulsion
Next step: Stop procedure. Reverse anticoagulation (protamine for heparin). Emergent IR: hepatic arteriogram for arterial injury; if venous bleeding: Gelfoam embolization of tract. If hemodynamically unstable: surgery.
Problem
rtPA infusion — fibrinogen drops below 100 mg/dL
Likely cause: Systemic fibrinogenolysis from rtPA
Next step: Hold lysis. Cryoprecipitate 10 units IV. Restart when fibrinogen >150 mg/dL. Consider reducing rtPA rate to 0.5 mg/h. Check fibrinogen every 6h during active lysis.
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Complications
Immediate
- Intraperitoneal/hepatic hemorrhage from transhepatic tract — always embolize on sheath withdrawal
- Intracranial hemorrhage (ICH) during lysis (~0.2–0.4%) — new neurologic symptoms = stop lysis immediately
- Bowel perforation if established infarction (lysis cannot reverse infarcted bowel)
- Pneumothorax from right intercostal access
Delayed
- Re-thrombosis without adequate anticoagulation — minimum 6 months anticoagulation required
- Portal vein cavernous transformation if not treated adequately (develops over months)
- Hepatic failure in patients with preexisting liver disease
- Short bowel syndrome if bowel resection required for infarction
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Post-Procedure Care
Inpatient Monitoring
- Surgical admission post-CDT — surgery team must remain involved throughout
- Serial abdominal exams q4h — any peritoneal signs = emergent surgical exploration
- Serial lactates q6h — normalization = bowel viability restored; persistent elevation = ongoing ischemia
- CT portal venous phase at 24–48h after lysis completion — confirm thrombus burden reduction, bowel wall normalization
Anticoagulation & Workup
- Minimum 6 months therapeutic anticoagulation — warfarin INR 2–3 or DOAC
- If underlying prothrombotic condition identified: lifelong anticoagulation
Hypercoagulable Workup
- Factor V Leiden, prothrombin G20210A mutation
- Antiphospholipid antibodies (aCL, lupus anticoagulant, anti-β2GP1)
- Antithrombin III, Protein C, Protein S
- JAK2 V617F — myeloproliferative neoplasms cause 25–40% of splanchnic vein thromboses; SMV thrombosis can be presenting manifestation of occult MPN
- Paroxysmal nocturnal hemoglobinuria (PNH) screen
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Critical Pearls
✶
Surgery first or concurrent: IR intervention in SMV thrombosis must be coordinated with surgery. If bowel appears infarcted (pneumatosis + portal gas + sepsis), no IR procedure will help — go to the OR. IR is for subacute ischemia without frank infarction.
✶
Extensive thrombus = poor prognosis even with CDT: Response to CDT is limited if thrombus is organized. Early intervention (within 48–72h of symptom onset) has significantly better outcomes than late (>1 week) cases.
✶
Always anticoagulate first: Even if IR intervention is planned, start UFH immediately. Anticoagulation alone is effective for many cases of SMV thrombosis. IR is an adjunct for failures, not first-line.
✶
Draw hypercoagulable workup before anticoagulation: At minimum draw JAK2 V617F — myeloproliferative neoplasms cause 25–40% of splanchnic vein thromboses. Once anticoagulation is started, some assays (Protein C/S, AT-III) become unreliable.
✶
Anticoagulate for ≥6 months: Recurrent thrombosis without adequate anticoagulation is high. Most guidelines recommend minimum 6 months. If underlying prothrombotic state: indefinite.
✶
Tract embolization is critical: Without Gelfoam/coil embolization of the transhepatic tract, hepatic hemorrhage and hemoperitoneum are significant risks as anticoagulation restarts post-procedure. Never skip this step.
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References & Resources
Key Guidelines
- ACCP/ASH Thrombosis Guidelines
- AASLD Portal Vein Thrombosis Management (2021)
- European Association for the Study of the Liver (EASL) Clinical Practice Guidelines (2016)
Primary References
- Acosta S, Björck M. Acute thrombo-embolic occlusion of the superior mesenteric artery: a prospective study in a well-defined population. Eur J Vasc Endovasc Surg. 2003.
- Brunaud L, et al. Incidence and risk factors of portal or mesenteric thrombosis after laparoscopic splenectomy. Ann Surg. 2004.
- Hollingshead M, et al. Transcatheter thrombolytic therapy for acute mesenteric and portal vein thrombosis. J Vasc Interv Radiol. 2005.
- Condat B, et al. Recent portal or mesenteric venous thrombosis. Gastroenterology. 2000.