Portal vein thrombosis (PVT) refers to a blood clot partially or completely occluding the portal vein. While generally rare, it is more commonly found in individuals with hepatic cirrhosis.
Some patients with acute PVT may experience rapid and sudden onset of right upper quadrant pain, nausea and possibly fever. On physical exam, there is tenderness in the right upper quadrant and epigastric regions. Additionally, the underlying event that precipitated the PVT will present with its own clinical picture such as in cases with appendicitis, pancreatitis, infection, etc. However, this acute phase in most patients is asymptomatic as clinical manifestations usually occur during the subacute or chronic stage.
Once the patient develops PVT, one of two pathways will occur 1) the thrombus spontaneously resolves resulting in the alleviation of symptoms or 2) collateral vessels form which causes relief of symptoms. If the latter occurs, the clinical picture becomes distorted and the diagnosis is therefore frequently missed. Eventually patients with collateral vasculature develop portal hypertension.
In patients with chronic PVT, one of the most common findings on physical exam is splenomegaly, which is observed in 75% to 100% of patients. Hepatomegaly may also be seen while ascites is not common.
Patients with preexisting liver disease will exhibit certain clinical signs. The stigmata of chronic liver disease includes spider angiomata, palmar erythema, and caput medusa. The latter is a strong indication of portal hypertension. It occurs due to restructuring of the umbilical vein with collateral vessels . Note that liver disease is associated with other signs and symptoms as well.
A thorough history and assessment of underlying diseases and conditions should be obtained. Also a detailed physical exam is pertinent as it will yield clues regarding chronic liver diseases. PVT should be suspected in patients with portal hypertension or any of the risk factors discussed previously.
Laboratory testing includes liver functions tests (LFTs) and any other pertinent studies relevant to the clinical picture. If no liver cirrhosis or malignancy is present, LFTs are mildly elevated. Additionally, studies for coagulation disorders may be warranted if no etiology is determined.
Doppler ultrasonography is the imaging of choice. Its sensitivity and specificity for PVT range from 60% to 100% . This mode of imaging can identify the thrombus, which displays as a solid, hyperechoic lesion in the portal vein. It also detects collateral vessels in addition to cavernomatous transformation . Furthermore, ultrasonography will demonstrate the absence blood flow. Endoscopic use of ultrasound (EUS) for PVT exhibits sensitivity and specificity of 81% and 93%, respectively .
MRI is helpful in cases with hepatic malignancies for evaluation of liver parenchyma. Additionally, this measures portal and hepatic blood flow to aid in surgical planning. CT with contrast displays the thrombus as a nonenhanced lesion in the lumen. This is beneficial in evaluating possible causes or complications such as ischemic bowel . Angiography is commonly used in surgical planning prior to liver transplantation or a shunting procedure.
Thrombolysis and anticoagulation
In terms of thrombolysis, PVT is treated locally through the transhepatic route. The drug regimen consists of tissue-type plasminogen activator (tPA) followed by long term prophylactic therapy with coumadin for at least 3 months. Patients with inherited coagulation disorders require lifelong therapy. Additionally, anticoagulation treatment is recommended after shunt placement.
In cases with variceal hemorrhage, it is pertinent to stop the bleeding and prevent recurrent episodes. Therapy includes intravenous octreotide (successful in 85% of patients) and endoscopic ligation/banding (successful in 95% with acute bleeding). Beta blockers such as propranolol can be used to prevent future bleeding. Due to these treatments, the use of shunts have decreased. This is beneficial since surgery is associated with mortality.
Shunt surgery in treatment of variceal bleeding is debatable. The favored type is the distal splenorenal shunt. Another type called transjugular intrahepatic portosytemic shunting (TIPS) is generally not recommended as it requires frequent monitoring after placement. TIPS is an option for cirrhotic patients with uncontrollable variceal bleeding. Additionally, it can be performed as a bridge to liver transplantation.
In neonates and children, treating the precipitating cause of PVT is key.
Patients without underlying liver cirrhosis or malignancy have a good prognosis with a mortality rate under 10%. In addition, the 10 year survival rate is 75%. If cirrhosis or malignancy exist, these patients have a poor prognosis.
Children with PVT do well since malignancy and cirrhosis are not observed much in this population. The 10 year survival rate is above 70%.
The causes of PVT varies among the age groups.
Neonates and children
Half of all cases in this population are secondary to abdominal infection. Furthermore, neonatal sepsis secondary to umbilical catheter placement accounts for 10% to 26% of patients with PVT. Congenital abnormalities in the hepatobiliary system are responsible for 20% of portal vein obstruction and thrombosis in children. In terms of risk factors, appendicitis is associated with PVT formation.
24% to 32% of PVT cases are secondary to liver cirrhosis. The risk of developing PVT increases with more severe cases. Malignancy, the other frequent etiology, results in 21% to 24% of cases. Specifically, hepatocellular carcinoma and pancreatic carcinoma account for a majority of these . PVT in malignancy results from tumor compression, coagulation dysfunction, or vascular invasion.
Appendicitis, pancreatitis, cholecystitis, and other inflammatory conditions are the most common local risk factors. Adenopathy, fine needle aspiration in the abdomen, systemic inflammatory response system, and surgical trauma in the abdomen are less common local factors. Systemic risk factor include neoplasms and hypercoagulable disorders. The latter includes factor V Leiden and protein C deficiency.
The annual incidence of PVT is 0.7 per 100,000 population, the prevalence is 3.7 per 100,000 population. While it is rare in the general population, certain conditions such as liver cirrhosis exhibit higher occurrences. The prevalence of PVT in liver cirrhosis ranges from 4.4% to 15%. In developed nations, 5% to 10% of cases with portal hypertension are attributed to PVT . In developing nations, this number can reach 3 times as much since intrabdominal infections are more common.
Note that severity of liver cirrhosis is associated with higher prevalence of PVT. Individuals with early disease status exhibit 1% prevalence while those awaiting liver transplantation demonstrate 30% prevalence. In patients with hepatocellular carcinoma, the incidence of PVT ranges from 10% to 40%.
The site of origin of the thrombus varies according to the pathology. For example in liver cirrhosis, the blood clots propagate from the liver to the extrahepatic portal vein. The same occurs with hepatocellular carcinoma. This is in contrast to other causes of PVT in which the thrombus develops in the portal vein. In cases such as pancreatitis, the clot travels from the splenic vein to the portal vein.
Hypercoagulable thrombosis is either inherited or acquired. The former is characterized by mutations in prothrombin gene and deficiencies in the factors that play a role in the clotting cascade. Acquired hypercoagulable states are usually due to deficiency of antithrombin III secondary to pathological conditions such as sepsis, disseminated intravascular coagulation, or hepatic dysfunction.
An obstruction causes stasis of portal blood flow, and this results in the liver losing a significant portion of its perfusion (two thirds of blood supply). In individuals with cirrosis or other liver disease, this would affect hepatic function . In patients with no preexisting liver conditions, the body modifies its circulation and patients can remain asymptomatic. There are two mechanisms that occur. First, vasodilation of hepatic artery  maintains hepatic blood flow. Additionally, there is a rapid formation of collateral circulation as the systemic and splanchnic vascular physiology adapt . The collateral vasculature form a network known as cavernoma. These two mechanisms allow liver blood flow in the initial stages of PVT.
The two prophylactic regimens below provide promising treatment.
One small trial explored the prevention of PVT using enoxaparin in patients with underlying cirrhosis and Child-Pugh score of 7 to 10. In a 12 month period, it was effective in PVT prophylaxis. Additionally, enoxaparin demonstrated improvement in survival as well as a delay in liver decompensation.
Another study observed that the incidence of PVT post splenectomy is decreased with prophylactic use of antithrombin III concentrates.
Portal vein thrombosis (PVT) is characterized by a blood clot in the vasal lumen of portal vein  that results in a partial or complete obstruction. There are numerous causes including underlying hepatic disease, malignancy, inflammatory conditions, and hypercoagulable disorders. PVT is not common in the general population but has a higher prevalence in patients with liver cirrhosis as well as in patients with hepatocellular carcinoma. PVT in these two disorders is associated with higher mortality.
When a PVT forms, the thrombus either resolves spontaneously or the vasculature adapts to the new hemodynamics. Symptoms subside in either of these pathways. Hence PVT does not usually present acutely, therefore, the diagnosis is often missed. Gradually, existing PVT results in portal hypertension which manifests in key signs on the physical exam. Hence a PVT is diagnosed at this chronic phase.
In patients with portal hypertension, the causes and risk factors should be assessed thoroughly. This is followed by appropriate laboratory studies and imaging. The imaging of choice is doppler ultrasonography, which demonstrates the thrombus and other relevant findings.
Portal vein thrombosis is a blood clot that blocks the portal vein, which is the blood vessel that travels from the intestines to the liver. The block can be partial or complete. There are many causes such as preexisting liver diseases, liver cancer, infections, inflammation, and others as well. While there are a number of causes for the blood clot formation, the main cause is a condition called liver cirrhosis, which means the liver is scarred. This can cause the blood flow to slow down, and more likely to cause a blood clot.
While most people do not experience symptoms, the blood clot can remain and gradually cause problems. For example, the block in the blood vessel increases the pressure in the portal. This results in a condition called portal hypertension. This can cause the blood vessels in the stomach and esophagus to bleed. Since these regions receive a big blood supply, they can bleed a large amount.
The doctor will obtain the medical history and perform a thorough physical exam in all patients. There are certain signs that the doctor will look for. Also, there are important laboratory tests to assess the liver function and any other condition that may have caused this blood clot. Finally, there are useful imaging studies. The most favored one is ultrasonography. It is inexpensive and noninvasive. This will find the clot and provide important information about the blood vessels.
The treatment of the blood clots involves two phases. The first phases is with a drug that breaks the clot. The second part is for the prevention of future clots. This second treatment can last for 3 months or possibly more depending on the patient.
In patients with bleeding, there are surgical procedures and treatment options available.