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===Surgery===
===Surgery===
Surgery is not the first-line treatment option for patients with portal vein thrombosis. [[Surgery]] is usually reserved for patients with either medical failed therapy, [[liver failure]], and [[cirrhosis]].


===Primary Prevention===
===Primary Prevention===

Revision as of 20:03, 19 December 2017

Portal vein thrombosis Microchapters

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Patient Information

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Portal vein thrombosis from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Diagnostic Study of Choice

History and Symptoms

Physical Examination

Laboratory Findings

Electrocardiogram

X Ray

CT

MRI

Echocardiography or Ultrasound

Other Imaging Findings

Other Diagnostic Studies

Treatment

Medical Therapy

Surgery

Primary Prevention

Secondary Prevention

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

Overview

Historical Perspective

Portal vein thrombosis was first discovered by Balfour and Stewart in 1868. In 1868, G201210A mutations were first implicated in the pathogenesis of portal vein thrombosis. In 1945, Allan Whipple, an American surgeon, reported treatment of some cases of the portal hypertension with shunts. He eventually tried shunts between different mesenteric veins. Finally, he found portocaval shunt as the best choice. In 1980s, researchers have observed that endoscopic sclerotherapy is more efficient than surgical shunting in preventing recurrent variceal bleeding.

Classification

Portal vein thrombosis may be classified according to the extension into 4 groups including confined to the portal vein beyond the confluence of the splenic vein, extended to the superior mesenteric vein, but with patent mesenteric vessels, extended to the whole splanchnic venous system, but with large collaterals, and extended to the whole splanchnic venous system with only fine collaterals. Based on the duration of symptoms, portal vein thrombosis may be classified as either acute or chronic.

Pathophysiology

It is thought that vein thrombosis is caused by Virchow's triad which includes reduced portal blood flow, hypercoagulable state, vascular endothelial injury. There are two mechanisms that contribute in loss of portal vein blood flow to liver, arterial rescue and venous rescue. It is a rapid process and takes a few days to start and 3-5 weeks to complete after portal vein obstruction. Collateral vessel joins to form cavernoma which connects the proximal and distal part of thrombosed portal vein. Finally, the portal vein becomes fibrosed, thin cord. All these events leads to low systemic vascular resistance and high cardiac output. These are the characterstic findings of hyperkinetic circulation.

Causes

Portal vein thrombosis may be caused by inherited prothrombotic disorders and acquired thrombophilic disorders. Less common causes of portal vein thrombosis include acquired conditions such as cirrhosis andhepatocellular carcinoma and procedures such as abdominal surgery or surgical injury of the portal vein axis and splenectomy.

Differentiating portal vein thrombosis from Other Diseases

Epidemiology and Demographics

The incidence of portal vein thrombosis in cirrhotic patients is unknown. The prevalence of portal vein thrombosis is approximately 5000-10,000 per 100,000 in overall cases of portal hypertension in developed counties and 40,000 per 100,000 in developing countries. The overall mortality rate of portal vein thrombosis is less than 10% except for patients with malignancy or cirrhosis. Patients of all age groups may develop portal vein thrombosis. There is no racial predilection to portal vein thrombosis. Portal vein thrombosis affects men and women equally.

Risk Factors

Common risk factors in the development of portal vein thrombosis include cirrhosis, pancreatitis, duodenal ulcer, cholecystitis, Crohn’s disease, ulcerative colitis and cholecystectomy, diverticulitis and appendicitis . Less common risk factors in the development of portal vein thrombosis include oral contraceptives, pregnancy or puerperium, and hyperhomocysteinemia.

Screening

There is insufficient evidence to recommend routine screening for portal vein thrombosis.

Natural History, Complications, and Prognosis

If left untreated, patients with portal vein thrombosis may progress to develop portal cavernoma, gastric or esophageal varices/bleeding, hepatic encephalopathy, splenomegaly, portal biliopathy or cholangiopathy. Depending on the extent of the model for end-stage liver disease score at the time of diagnosis, the prognosis may vary. However, the prognosis is generally regarded as good.

Diagnosis

Diagnostic Criteria

Ultrasonography is the gold standard test for the diagnosis of portal vein thrombosis. The following result of ultrasonography is confirmatory of portal vein thrombosis is portal cavernoma (multiple tortuous small vessels replacing the portal vein) and absence or reduced flow in portal vein.

History and Symptoms

Common symptoms of portal vein thrombosis include abdominal pain or distention, diarrhea, nausea and vomiting, and anorexia. Less common symptoms of portal vein thrombosis include weight loss, fever, ascites, jaundice, and bloody stools.

Physical Examination

Patients with portal vein thrombosis usually appear ill. Common physical examination findings of portal vein thrombosis include abdominal pain or distention, splenomegaly and signs of ascites.

Laboratory Findings

Laboratory finding is usually normal among patients with portal vein thrombosis. In patients with cirrhosis, laboratory findings may demonstrate an elevated bilirubin, low platelet count, prolonged international normalized ratio (INR), or renal insufficiency.

Electrocardiogram

There are no ECG findings associated with portal vein thrombosis.

X-ray

There are no x-ray findings associated with portal vein thrombosis.

Ultrasound

Ultrasound may be helpful in the diagnosis of portal vein thrombosis. Findings on an ultrasound diagnostic of portal vein thrombosis include echogenic material obstructing lumen of vessel, complete or partial absence of flow in portal vein, and collateral circuits by-passing the obstructed vessel.

CT scan

Abdominal CT scan may be helpful in the diagnosis of portal vein thrombosis. Findings on CT scan suggestive of hyperattenuating material in the portal vein lumen, nonenhanced intraluminal-filling defect, Lack of luminal enhancement, increased hepatic enhancement in the arterial phase and decreased hepatic enhancement in the portal phase.

MRI

Abdominal MRI may be helpful in the diagnosis of portal vein thrombosis. Findings on MRI diagnostic of portal vein thrombosis include filling defect that partially or completely occludes the vessel lumen in the portal venous phase, clot appears isointense on T1- weighted images, and usually has a more intense signal on T2 images, and presence of varices.

Other Imaging Findings

Contrast enhanced ultrasonography(CEUS) may be helpful in the diagnosis of portal vein thrombosis. Findings on CEUS suggestive of portal vein thrombosis include pulsatile flow in a portal vein thrombus, absence of enhancement of the portal vein thrombus in the arterial phase, and differentiate between benign and malignant portal vein thrombosis.

Other Diagnostic Studies

There are no other diagnostic studies associated with portal vein thrombosis.

Treatment

Medical Therapy

Medical therapy for portal vein thrombosis include anticoagulation to maintain INR between 2 to 3 and it improves recanalization rates.

Surgery

Surgery is not the first-line treatment option for patients with portal vein thrombosis. Surgery is usually reserved for patients with either medical failed therapy, liver failure, and cirrhosis.

Primary Prevention

There are no established measures for the primary prevention of portal vein thrombosis.

Secondary Prevention

There are no established measures for the secondary prevention of portal vein thrombosis.

References


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