Basics
Description
- Cavernous transformation: the collection of collaterals that develop around an obstructed vessel
- Portal vein obstruction
- Can occur anywhere along the course of the main portal vein or splenic vein, between the hilum of the spleen and the porta hepatis
- In pediatrics, obstruction is most typically of the portal vein.
- Major cause of prehepatic portal hypertension
Epidemiology
- Most children with portal vein thrombosis present between birth and 15 years of age.
- Acute presentation is rare.
- Chronic cases present with complications of portal hypertension.
- Gastrointestinal (GI) bleeding is more typical in patients presenting <7 years of age.
- Splenomegaly in the absence of symptoms is more typical for patients aged 5-15 years.
Risk Factors
Genetics
A genetic basis of this problem has not been identified, although congenital abnormalities of the heart, major blood vessels, biliary tree, and renal system are often found.
Pathophysiology
- In cirrhosis and hepatic malignancies, the thrombus usually begins intrahepatically and spreads to the extrahepatic portal vein.
- In most other etiologies, the thrombus usually starts at the site of origin of the portal vein.
- Occasionally, thrombosis of the splenic vein propagates to the portal vein, most often resulting from an adjacent inflammatory process (e.g., severe pancreatitis).
- Asymptomatic splenomegaly or upper GI hemorrhage results from extrahepatic portal hypertension.
- Less commonly, ascites or failure to thrive, and portopulmonary hypertension
Etiology
50% of portal vein obstructions are idiopathic. Identified causes include the following:
- Congenital vascular anomaly
- Portal vein malformation
- Webs or diaphragms within the portal vein
- Clot resulting from a hypercoagulable state
- Clot from other causes:
- Omphalitis
- Umbilical vein catheterization
- Portal pyelophlebitis
- Intra-abdominal sepsis
- Surgery near the porta hepatis
- Sepsis
- Cholangitis
- Dehydration
- Trauma
- Other causes for portal vein obstruction in older children:
- Ascending pyelophlebitis from perforated appendicitis
- Primary peritonitis, cholangitis, and pancreatitis causing a splenic vein thrombosis
- Inflammatory bowel disease
Diagnosis
History
- Splenomegaly (see "Splenomegaly"¯ topic for complete differential)
- Exposure to infectious mononucleosis
- Metabolic storage disease (e.g., Gaucher disease)
- Malignancy (e.g., chronic myelogenous leukemia)
- History of prematurity and admission to NICU should alert the clinician to previous umbilical vein catheterization and increased risk of portal vein thrombosis.
Signs and Symptoms
- Clinical history and examination should concentrate on identifying possible causes predisposing to portal vein obstruction.
- Portal vein obstruction does not affect liver function unless the patient has an underlying liver disease (e.g., cirrhosis). This situation is partially due to a compensatory increased flow of the hepatic artery maintaining the total hepatic blood flow.
- Mild coagulation profile abnormalities
Physical Exam
- Splenomegaly
- Spleen is measured from the left anterior axillary line at the costal margin diagonally toward the umbilicus and inferiorly toward the iliac crest
- Hemorrhoids
Diagnostic Tests & Interpretation
Lab
- CBC: Leukopenia and thrombocytopenia will be present if there is hypersplenism.
- Aspartate aminotransferase/alanine aminotransferase/Ī³-glutamyl transferase: should be normal
- PT/PTT: may be abnormal if malabsorption is present
- Additional testing associated with hypercoagulable states (as clinically indicated)
- Protein C
- Protein S
- Antithrombin III levels
- Factor V Leiden mutation
- Activated protein C resistance
- Lupus anticoagulation evaluation
- Anticardiolipin antibodies (IgA, IgG, IgM)
- Antinuclear antibody
- Blood homocysteine
- Prothrombin 20-21-0 mutation
- Methylene tetrahydrofolate reductase mutation evaluation
- Factor VIII coagulant
- Reptilase time
- Heparin cofactor II
- Tissue plasminogen activator
- Plasminogen activator inhibitor-1
- Sticky platelet evaluation
- Paroxysmal nocturnal hemoglobinuria (genetics or flow cytometry evaluation)
Imaging
- Ultrasound with Doppler
- To examine portal vein flow and to identify collateral veins if there is cavernous transformation of the portal vein
- Liver may be slightly small but may be normal in texture.
- Remains the most useful imaging study
- CT angiography or MRV can give additional information if needed especially prior to planning a surgical portosystemic shunt procedure.
Diagnostic Procedures/Other
- Liver biopsy
- Not required for diagnosis nor performed routinely
- Exclude other etiologies
- Upper endoscopy and sigmoidoscopy: to define extent of varices
Pathologic Findings
- Portal hypertension: spider nevi, prominence of abdominal veins, splenomegaly
- Bruising: may be prominent when coexistent consumption of clotting factors
- Normal liver palpation and percussion
- Ascites rarely present
Differential Diagnosis
The differential diagnosis must exclude other causes of splenomegaly and portal hypertension.
Treatment
Additional Treatment
General Measures
- General goals of therapy are (1) to manage variceal hemorrhage and (2) to identify an underlying cause and/or determine if the patient is at risk for additional venous thrombosis or malignancy.
- Therapy for GI variceal hemorrhage:
- Octreotide infusion: 1 mcg/kg/h maximum 50 mcg/h
- Prophylactic variceal banding for large esophageal varices
- β-Blocker therapy
- Rex shunt (mesenterico-left intrahepatic portal vein shunt):
- Can be surgically addressed using the internal jugular vein, internal iliac vein, or dilated coronary vein, which is used to connect the superior mesenteric vein and the umbilical portion of the left portal vein (in the liver)
- Restores the physiologic intrahepatic portal vein perfusion
- Avoids the consequences of long-term portosystemic shunting, especially hepatic encephalopathy
- Portosystemic shunts: divert portal blood into the low-pressure systemic venous circulation. Classified into
- Nonselective shunts: These communicate the entire portal venous system to a systemic venous circulation such as the mesocaval shunt, proximal splenorenal shunt, and portacaval shunts. Nonselective shunts divert more blood into the systemic venous system, and patients are more likely to have encephalopathy.
- Selective shunts: These divert the gastrosplenic portion of the portal venous flow into the left renal vein or the inferior vena cava. The most common selective shunt is the distal splenorenal shunt (also known as the Warren shunt).
Ongoing Care
Follow-up Recommendations
Focus on growth parameters, early detection of malabsorption, presence of GI hemorrhage, and nutritional intervention.
- Aggressive contact sports should be actively discouraged in children with hepatosplenomegaly.
- All patients should be advised to restrict activities that could injure their already enlarged spleen. Spleen guards may be recommended.
- Patients should be told to avoid medicines that interfere with platelet function
- In addition, patients should avoid medications that increase BP, including many over-the-counter cold medications (e.g., phenylephrine), as this can increase splanchnic pressures and may provoke variceal bleeds.
Prognosis
- Long-term prognosis overall is considered good.
- Upper GI hemorrhage becomes less problematic as children become older.
- Rex shunt restores normal physiology and decreases portal pressure. In many centers, Rex shunt is performed as 1st-line therapy.
- Most patients receive β-blockers or undergo prophylactic banding. If the liver function remains normal, as in most cases, it is rare for encephalopathy to develop unless a large portosystemic shunt is created.
Complications
- Variceal hemorrhage from the upper tract or from the perianal varices
- Splenomegaly with hypersplenism:
- Thrombocytopenia
- Consumption coagulopathy
- Leukopenia
- Steatorrhea and protein-losing enteropathy occurs secondary to venous congestion of the intestinal mucosa.
- Degree of portal hypertension is variable and depends on the formation of spontaneous shunts that may decompress the portal hypertension. These autoshunts may predispose to the development of complications such as hepatic encephalopathy or hepatopulmonary syndrome.
- Spleen can undergo autoinfarction, resulting in intermittent episodes of pain.
- A large spleen is susceptible to traumatic rupture.
- Spontaneous splenic rupture may also occur (classically associated with infectious mononucleosis).
Additional Reading
- Fuchs J, Warmann S, Kardorff R, et al. Mesenterico-left portal vein bypass in children with congenital extrahepatic portal vein thrombosis: a unique curative approach. J Pediatr Gastroenterol Nutr. 2003;36(2):213-216. [View Abstract]
- Mileti E, Rosenthal P. Management of portal hypertension in children. Curr Gastroenterol Rep. 2011;13(1):10-16.
- Ryckman FC, Alonso MH. Causes and management of portal hypertension in the pediatric population. Clin Liver Dis. 2001;5(3):789-818. [View Abstract]
- Superina RA, Alonso EM. Medical and surgical management of portal hypertension in children. Curr Treat Options Gastroenterol. 2006;9(5):432-443. [View Abstract]
- Superina R, Shneider B, Emre S, et al. Surgical guidelines for the management of extra-hepatic portal vein obstruction. Pediatr Transplant. 2006;10(8):908-913. [View Abstract]
Codes
ICD09
- 452 Portal vein thrombosis
- 572.3 Portal hypertension
- 747.40 Anomaly of great veins, unspecified
ICD10
- I81 Portal vein thrombosis
- K76.6 Portal hypertension
- Q26.9 Congenital malformation of great vein, unspecified
SNOMED
- 57348003 Portal vein obstruction
- 34742003 Portal hypertension (disorder)
- 234131004 Splenoportal vascular anomaly (disorder)
FAQ
- Q: Should I restrict my child's activities and avoid certain medications?
- A: Contact sports should be limited or a spleen guard should be used. NSAIDs, including aspirin, should be avoided because of the risk of hemorrhage. Medications that increase blood pressure, including many nonprescription cold preparations, should also be avoided.