What could cause a large inferior mesenteric venous varix in a 53-year-old female?

Causes of Large Inferior Mesenteric Venous Varix in a 53-Year-Old Female

A 2.9 cm inferior mesenteric venous varix in this patient is most likely caused by portal hypertension from underlying liver disease, though splenic vein thrombosis, inferior mesenteric vein thrombosis from external compression, or rarely an arteriovenous fistula must also be considered.

Primary Diagnostic Consideration: Portal Hypertension

The most common cause of mesenteric venous varices is portal hypertension, which should be your first consideration 1.

Cirrhotic Portal Hypertension

• Evaluate for chronic liver disease including viral hepatitis B/C, non-alcoholic steatohepatitis, alcoholic liver disease, autoimmune hepatitis, hereditary hemochromatosis, Wilson's disease, and primary biliary cirrhosis 1
• The inferior mesenteric vein normally measures 3-6 mm (mean 3.9 mm) on CT; a diameter of 9 mm or greater suggests portal hypertension 2
• In cirrhotic patients with detectable inferior mesenteric vein flow (20% of cases), hepatofugal flow increases risk of ascites and liver decompensation but paradoxically reduces gastroesophageal variceal risk 3
• Assess Child-Pugh classification, as variceal prevalence correlates directly with disease severity (40% in Child A versus 85% in Child C) 4, 5

Non-Cirrhotic Portal Hypertension

• Consider idiopathic non-cirrhotic portal hypertension (INCPH) if liver biopsy excludes cirrhosis 1
• INCPH is associated with thrombophilia (40% prevalence in Western patients), immunological disorders, specific medications (azathioprine, didanosine), and HIV infection 1
• Clue for INCPH: low liver stiffness on transient elastography (<12 kPa) despite signs of portal hypertension 1
• Requires patent portal and hepatic veins on Doppler ultrasound or CT to diagnose 1

Secondary Causes to Exclude

Splenic Vein Thrombosis

• Isolated gastric and mesenteric varices can occur without cirrhosis when splenic vein thrombosis causes sinistral (left-sided) portal hypertension 1
• Most commonly caused by pancreatitis (acute or chronic), pancreatic tumors, or pancreatic surgery 1
• Results in isolated fundal gastric varices (IGV1) and can extend to inferior mesenteric venous system 1
• Splenectomy is definitive treatment with 100% success rate in controlling bleeding from these varices 1

Inferior Mesenteric Vein Thrombosis

• External compression from abdominal masses, large hiatus hernias containing pancreas, or other space-occupying lesions can cause IMV thrombosis and retrograde variceal formation 6
• Hypercoagulable states increase thrombosis risk 1
• Look for associated rectal varices (56.3% incidence with hepatofugal IMV flow versus 13.3% with hepatopetal flow) 3

Portal Vein Thrombosis (EHPVO)

• Extrahepatic portal vein obstruction leads to cavernomatous transformation and extensive portosystemic collaterals including mesenteric varices 1
• Associated with myeloproliferative neoplasms, antiphospholipid syndrome, inherited thrombophilia, pancreatitis, diverticulitis, and inflammatory bowel disease 1
• Diagnosis requires demonstrating absent portal vein lumen with serpiginous collateral channels in porta hepatis on Doppler ultrasound or contrast-enhanced CT/MRI 1

Arteriovenous Fistula (Rare)

• Inferior mesenteric arteriovenous fistulas are exceptionally rare (only 26 cases reported) but can cause venous hypertension and varix formation 7, 8
• Can be congenital or secondary to surgery/trauma 8
• Presents with flow-dependent symptoms ranging from minimal to severe heart failure from left-to-right shunt 8
• Diagnosis established by CT angiography showing early venous filling 8

Diagnostic Algorithm

Initial Workup

1. Obtain contrast-enhanced CT or MRI to assess portal vein patency, splenic vein patency, liver morphology, and exclude masses 1
2. Perform Doppler ultrasound to evaluate flow direction in portal system, splenic vein, and inferior mesenteric vein 1, 3
3. Check liver function tests including transaminases, alkaline phosphatase, bilirubin, albumin, PT/INR 1
4. Screen for chronic liver disease with hepatitis B/C serology, autoimmune markers, iron studies, ceruloplasmin, and alpha-1 antitrypsin 1

If Portal Hypertension Suspected

• Perform upper endoscopy to screen for esophageal and gastric varices 1, 4
• Consider liver biopsy if imaging suggests cirrhosis but etiology unclear, or if INCPH suspected 1
• Evaluate for thrombophilia including Factor V Leiden, prothrombin mutation, protein C/S deficiency, antiphospholipid antibodies 1

If Isolated Mesenteric Varices Without Esophageal Varices

• Specifically evaluate splenic vein for thrombosis with dedicated imaging 1
• Assess for pancreatic pathology including chronic pancreatitis or masses 1
• Consider colonoscopy or flexible sigmoidoscopy to evaluate for rectal varices 1

Critical Pitfalls to Avoid

• Do not biopsy suspected varices on endoscopy or colonoscopy; probe gently with closed forceps and look for blue hue and soft consistency 1
• Do not assume cirrhosis based solely on imaging showing liver surface nodularity and portal vein wall thickening, as INCPH can mimic cirrhosis radiologically 1
• Do not overlook splenic vein thrombosis as a cause of isolated mesenteric/gastric varices, as this requires different management than cirrhotic portal hypertension 1
• Confirm vascular nature with EUS and Doppler if diagnosis uncertain, showing anechoic/hypoechoic structure with flow in submucosa 1