1. PORTAL VEIN THROMBOSIS
Aswad H. Al.Obeidy
FICMS, FICMS GE&Hep
Kirkuk General Hospital

2. Portal Vein Thrombosis
Portal vein obstruction results from thrombosis, constriction, or invasion of the portal vein
The resulting portal hypertension leads to splenomegaly and formation of portosystemic collaterals and esophageal, gastric, duodenal, and jejunal varices
Varices proliferate in the porta hepatis and involve the gallbladder and bile duct
Upstream from the obstruction, the small intestine and colon become congested, and the stomach exhibits changes of portal hypertensive gastropathy. Mesenteric ischemia can occur if the thrombus extends into the mesenteric veins
Downstream from the clot, the liver usually maintains normal function and appears unaffected
Ascites may develop during the initial stages but usually recedes subsequently
Clinically, portal vein thrombosis usually is asymptomatic until variceal bleeding occurs

3. ETIOLOGY
Most cases of portal vein thrombosis have an identifiable cause related to hypercoagulability or to local factors such as inflammation, trauma, or malignancy
Less than 20% of cases are considered idiopathic
Better understanding of the multiple causes of hypercoagulability has led to the recognition that multiple coexisting risk factors are present in as many as 40% of affected patients
Infection, most often umbilical vein sepsis, is the main cause of portal vein thrombosis in children. Portal vein thrombosis is well documented after neonatal umbilical vein catheterization but resolves in greater than 50% of cases
In adults, cirrhosis or abdominal malignancies are responsible for more than one half of the cases of portal vein thrombosis

4. ETIOLOGY
The disorder occurs in at least 10% of patients with cirrhosis, presumably as a result of sluggish portal vein blood flow, but acquired and inherited hypercoagulable states can be identified in many patients with cirrhosis and portal vein thrombosis
Hepatocellular and pancreatic carcinomas are the most common malignant causes for portal vein thrombosis, usually because of a combination of hypercoaguability and invasion or constriction of the portal vein
Local inflammatory reactions resulting from acute or chronic pancreatitis are a common cause of portal vein thrombosis
Pylephlebitis, or septic portal vein thrombosis, can complicate intra-abdominal infections such as appendicitis, diverticulitis, and cholangitis
In addition, splenic vein trauma during splenectomy results in portal vein thrombosis in 8% of cases; the risk increases to 40% if a myeloproliferative disorder is present

5. Causes of Portal Vein Thrombosis
Hypercoagulable States
Antiphospholipid syndrome   
Antithrombin deficiency   
Factor V Leiden mutation   
Methylenetetrahydrofolate reductase mutation TT677   
Myeloproliferative disorder   
Nephrotic syndrome   
Oral contraceptives  
Paroxysmal nocturnal hemoglobinuria   
Polycythemia rubra vera   
Pregnancy   
Prothrombin mutation G20210A   
Protein C deficiency   
Protein S deficiency   
Sickle cell disease

6. Causes of Portal Vein Thrombosis
Inflammatory Diseases
Behçet's syndrome  
Inflammatory bowel disease  
Pancreatitis

7. Causes of Portal Vein Thrombosis
Infections
Appendicitis   
Cholangitis   
Cholecystitis   
Diverticulitis   
Liver abscess   
Schistosomiasis   
Umbilical vein infection

8. Causes of Portal Vein Thrombosis
Complications of Therapeutic Interventions
Alcohol injection   
Colectomy   
Endoscopic sclerotherapy   
Fundoplication   
Gastric banding   
Hepatic chemoembolization   
Hepatobiliary surgery   
Islet cell injection   
Liver transplantation   
Peritoneal dialysis   
Radiofrequency ablation of hepatic tumor(s)   
Splenectomy   
TIPS procedure   
Umbilical vein catheterization

9. Causes of Portal Vein Thrombosis
Impaired Portal Vein Flow
Budd-Chiari syndrome   
Cirrhosis   
Cholangiocarcinoma   
Hepatocellular carcinoma   
Nodular regenerative hyperplasia   
Pancreatic carcinoma   
Sinusoidal obstruction syndrome

10. Causes of Portal Vein Thrombosis
Miscellaneous
Bladder cancer   
Choledochal cyst   
Living at high altitude

11. CLINICAL FEATURES AND COURSE
Portal vein thrombosis is found with equal frequency in adults (mean age, 40 years) and children (mean age, 6 years)
The presenting manifestation is almost always hematemesis from variceal bleeding
Abdominal pain is unusual unless the thrombosis involves the mesenteric veins and causes intestinal ischemia
Splenomegaly usually is present
Ascites is uncommon, except in acute portal vein thrombosis or when the thrombosis complicates cirrhosis

12. CLINICAL FEATURES AND COURSE
Liver biochemical test results usually are normal
Occasionally, common bile duct varices can cause biliary obstruction
Even mimic cholangiocarcinoma on endoscopic retrograde cholangiopancreatography
Other unusual locations for ectopic varices in portal vein thrombosis include the gallbladder, duodenum, and rectum

13. CLINICAL FEATURES AND COURSE
Doppler ultrasonography is highly sensitive for detection of this disorder and reveals an echogenic thrombus in the portal vein , extensive collateral vessels in the porta hepatis, an enlarged spleen, and occasionally nonvisualization of the portal vein
When the diagnosis of portal vein thrombosis is still uncertain, magnetic resonance angiography is better than CT in demonstrating the typical changes of portal vein thrombosis
Portal venography usually is unnecessary unless a surgical shunt is being considered
Evaluation of the patient for precipitating hypercoagulable risk factors may require a consultation with a hematologist

14. Natural history of portal vein thrombosis
Is related primarily to the underlying disorder
In the absence of cirrhosis, cancer, and mesenteric vein thrombosis, the 10-year survival rate for patients with portal vein thrombosis is greater than 80%
Only 2% experience fatal variceal hemorrhage
Variceal bleeding caused by portal vein thrombosis has a much better outcome than that observed with variceal bleeding caused by cirrhosis
Because of preserved hepatic function and lack of coagulopathy in patients with thrombosis alone
In addition, development of spontaneous portosystemic collaterals can lead to a reduced frequency of recurrent variceal bleeding in patients with portal vein thrombosis

15. TREATMENT
Endoscopic band ligation or sclerotherapy is first-line therapy for variceal bleeding in patients with portal vein thrombosis
Sessions should be repeated until the varices are obliterated
Therapy with beta blockers is beneficial in preventing initial and, in combination with endoscopic therapy, recurrent variceal bleeding
Recurrent or refractory variceal bleeding or bleeding from varices distal to the esophagus is an indication for placement of a portosystemic shunt
TIPS is an option if the technical challenge of gaining access to the portal vein can be overcome

16. TREATMENT
Focal malignant portal vein obstruction can be stented percutaneously, with successful control of refractory variceal bleeding and ascites
Elective mesocaval and splenorenal shunts and the extended Sugiura procedure (esophagogastric devascularization and transection)[81] also have been performed successfully in patients with portal vein thrombosis, with low mortality and long survival
Anticoagulation is recommended in patients with acute portal vein thrombosis, to prevent cavernous transformation and complications of portal hypertension
Spontaneous recanalization with acute thrombosis is rare
Therapeutic recanalization can be achieved in greater than 80% of the cases with anticoagulants (intravenous heparin or subcutaneous LMWH, followed by warfarin to achieve an INR of 2.0 to 2.5 for at least 6 months)

17. TREATMENT
Prompt use of broad-spectrum antibiotics in cases of septic pylephlebitis also leads to resolution of the thrombosis
Systemic and selective venous infusions of thrombolytic agents have been used successfully in acute portal vein thrombosis and are beneficial when the thrombosis is associated with mesenteric vein thrombosis and intestinal ischemia
Chronic anticoagulation should be considered in patients with portal vein thrombosis and a recognized hypercoagulable state, surgical shunt, or concomitant mesenteric vein thrombosis
anticoagulants are not recommended for chronic portal vein thrombosis, especially when associated with cavernous transformation
liver transplantation for liver failure complicated by portal vein thrombosis is now possible