A 55-year-old man with a history of chronic alcoholism and recurrent bouts of pancreatitis presented with new onset of hematemesis and hematochezia. He complained of an acute exacerbation of his usual chronic left-sided abdominal pain. Vital signs showed tachycardia with a heart rate of 115 bpm and a blood pressure of 95/62 mm Hg. Physical examination was remarkable for epigastric and left upper quadrant tenderness without stigmata of cirrhosis. Laboratory work was significant for hemoglobin of 7.5 g/dL, a hematocrit of 22.2%, an amylase of 397 IU/L, and a lipase of 264 U/L. Hepatic function panel was within normal limits. After initial resuscitation, upper endoscopy was undertaken, showing actively bleeding gastric varices, but no evidence of esophageal varices. Hemostasis was obtained endoscopically. Subsequent computed tomography (CT) imaging demonstrated an atrophic calcified pancreas with occlusion of the splenic vein, splenomegaly, and multiple perigastric collaterals. No tumor was seen in the pancreas, and there was no evidence of cirrhosis. The patient subsequently underwent a laparoscopic splenectomy prior to discharge. Figures 49-1,49-2,49-3 show representative imaging of a patient with splenic vein thrombosis (SVT).

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  SVT was first recognized over 80 years ago as a cause of gastro-intestinal (GI) bleeding.¹

  
  
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  The exact incidence of SVT is unknown as the majority of patients are asymptomatic. It is also unknown how many patients with isolated SVT later go on to develop gastric varices.

  
  
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  Between 45% and 72% of patients initially present with gastric variceal bleeding, with most of them requiring splenectomy.²

  
  
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  SVT complicates pancreatitis or pancreatic pseudocysts in 7% to 20% of patients.^3,4

  
  
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  Patients with incidentally discovered gastric varices may have a lower risk of bleeding. The risk of variceal hemorrhage is 5% for patients with CT-identified varices compared to 18% for endoscopically identified varices. Of those, only 4% develop variceal hemorrhage and/or require splenectomy.⁵

  
  
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  Partial occlusion of the splenic vein is considerably more common than complete occlusion, with 54% to 89% of patients with SVT demonstrating only partial occlusion.^6,7

  
  
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  The reported frequency has increased with the improved sensitivity of imaging modalities such as CT, magnetic resonance imaging (MRI), and ultrasound (US).

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  Causes of SVT include both acute and chronic pancreatitis, pancreatic malignancies, adenopathy from metastatic disease or lymphoma, idiopathic retroperitoneal fibrosis, and iatrogenic causes such as after splenectomy, gastrectomy, or a splenorenal shunt.^2,8,9

  
  
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  Although early reports found pancreatic carcinoma to be the most common cause of SVT, more recent reviews have noted pancreatitis as the inciting event in up to 60% of cases.^2,9

  
  
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  It is unknown if SVT is more likely in patients with alcoholic pancreatitis, as opposed to pancreatitis due to other causes.

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  The path to development of SVT differs depending on the disease process that initiates the thrombosis.

  
  
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  In acute pancreatitis, SVT is initiated by local prothrombotic inflammatory changes in the vascular endothelium of the splenic vein as it courses along the posterior aspect of the pancreatic tail, putting it in direct contact with peripancreatic inflammatory tissue.¹⁰

  
  
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  Extrinsic compression from a pseudocyst, low pancreatic perfusion, or later development of pancreatic fibrosis may leadto SVT.⁵

  
  
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  Enlarged lymph nodes, whether from malignant or inflammatory causes in the retroperitoneal, pancreatic, or perisplenic areas can compress the splenic vein, leading to obstruction.²

  
  
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  Once occlusion of the splenic vein occurs, the most common collateral pathways use the short gastric veins for decompression. This ultimately leads to increased pressure within the submucosal veins of the fundus, resulting in gastric varices.⁸

  
  
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  Anatomic variants and less common collateral pathways can lead to variations in the location of varices. If the coronary vein joins the splenic vein proximal to the obstruction, isolated esophageal varices can occur.¹¹ Additionally, the left gastroepiploic vein can collateralize with the left colic and inferior mesenteric veins, leading to colonic varices.⁷ The incidence of both variations is rare.