What is the appropriate workup for a suspected portal vein thrombosis in an adult patient with a history of liver disease or a condition that increases the risk of blood clots?

Workup for Suspected Portal Vein Thrombosis

Begin with Doppler ultrasound as the first-line imaging study, followed immediately by contrast-enhanced CT scan in the portal venous phase for diagnostic confirmation and assessment of thrombus extent, location, and degree of luminal obstruction. 1, 2

Initial Diagnostic Imaging

• Perform Doppler ultrasound immediately as the initial screening test, looking specifically for absence of portal vein flow, hyperechoic thrombus in the portal lumen, and flow reversal within the portal system 2
• Ultrasound has diagnostic sensitivity >75% for detecting PVT 1
• Proceed directly to contrast-enhanced CT scan (portal venous phase) to definitively confirm diagnosis, assess thrombus extension into splenic and superior mesenteric veins, and determine degree of luminal obstruction 1, 2
• MR imaging can be used as an alternative to CT if CT is contraindicated or unavailable 1
• Document standardized characteristics: location (main portal vein, right/left branches, splenic vein, superior mesenteric vein), extent, degree of luminal obstruction (partial vs complete), and chronicity (recent <6 months vs chronic) 1

Critical Clinical Assessment

Immediately evaluate for intestinal infarction in any patient presenting with severe abdominal pain, rectal bleeding, moderate/massive ascites, or multiorgan dysfunction, as this represents a life-threatening complication requiring urgent intervention 1

• Assess for signs of bowel ischemia: persistent severe abdominal pain, bloody stools, peritoneal signs, lactic acidosis 1
• This assessment must occur before initiating anticoagulation 3, 2

Establish Underlying Liver Disease Status

Determine presence or absence of cirrhosis as this fundamentally changes the thrombophilia workup and treatment approach 1

If Cirrhosis is Present:

• Assess Child-Pugh classification (A, B, or C) as this determines anticoagulation choice 1, 4
• Do NOT perform extensive thrombophilia testing in cirrhotic patients, as it rarely changes management and inherited thrombophilias are uncommon contributors 1
• Evaluate for hepatocellular carcinoma with AFP and imaging, as malignant thrombus must be excluded 1

If No Cirrhosis (Non-Cirrhotic PVT):

Perform comprehensive thrombophilia and systemic disease workup as these patients require different management 1

Mandatory Thrombophilia Testing:

• Myeloproliferative neoplasms: JAK2V617F mutation (even with normal blood counts), and if negative, calreticulin mutation screening 1
• Inherited thrombophilias: Factor V Leiden mutation, prothrombin G20210A gene variant 1
• Protein deficiencies: Protein C, Protein S, antithrombin levels 1
• Antiphospholipid syndrome: Antiphospholipid antibodies (repeat after 12 weeks if positive) 1
• Paroxysmal nocturnal hemoglobinuria testing 1

Local/Systemic Risk Factor Assessment:

• Intra-abdominal inflammatory conditions: Recent pancreatitis, inflammatory bowel disease, appendicitis, diverticulitis 1
• Recent surgical procedures: Bariatric surgery, splenectomy 1
• Abdominal malignancies: CT imaging should evaluate for pancreatic, hepatobiliary, or other intra-abdominal cancers 1
• Autoimmune disorders screening 1

Pre-Anticoagulation Variceal Screening (If Cirrhosis Present)

Perform upper endoscopy to screen for esophageal varices before initiating anticoagulation 3

• If varices are present, ensure adequate prophylaxis with either non-selective beta-blockers or endoscopic band ligation before starting anticoagulation 3, 2
• This step is critical to minimize bleeding risk during anticoagulation 3

Laboratory Assessment

• Complete blood count: Assess platelet count (anticoagulation generally safe if >50 × 10⁹/L) 1, 3
• Liver function tests: ALT, AST, bilirubin, albumin, INR for Child-Pugh scoring 1
• Renal function: Creatinine for anticoagulant dosing adjustments 1
• Do NOT use INR or PT to assess bleeding risk in cirrhotic patients, as these tests do not predict bleeding complications 1, 4

Assessment of Portal Flow Velocity

• Measure portal vein flow velocity by Doppler ultrasound, as velocities <10-15 cm/s are associated with increased PVT risk and may influence long-term anticoagulation decisions 1

Common Pitfalls to Avoid

• Never delay imaging waiting for laboratory results; imaging should be performed emergently 2
• Do not assume ultrasound alone is sufficient for treatment planning; CT or MRI is required for complete assessment 1
• Do not perform extensive thrombophilia workup in cirrhotic patients as it rarely changes management 1
• Never start anticoagulation before excluding bowel infarction in symptomatic patients 1, 3
• Do not use standard coagulation tests (INR, PT) to assess bleeding risk in cirrhotic patients 4