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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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)

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