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Splanchnic venous thrombosis involves thrombosis in the mesenteric, splenic, or portal veins, with or without the hepatic veins.
The superior mesenteric and splenic veins join to form the portal vein, which supplies up to 75% of blood to the liver.
The incidence is estimated to be between 1 to 4 cases per million people.
The portal and mesenteric veins are most commonly affected, while hepatic vein thrombosis, known as Budd-Chiari syndrome, is less frequent.
SVT can present with a wide range of symptoms.
SVT symptoms depend on the location of the thrombosis.
SVT symptoms: abdominal pain, gastrointestinal disturbances, and potential complications such as bowel ischemia.
Typical symptoms include abdominal pain or mid abdominal colicky pain,, abdominal distention, rebound tenderness, guarding, fever, anorexia, nausea, vomiting, diarrhea, gastrointestinal bleeding, hepatomegaly, and ascites.
Rarely SVT may be an incidental finding.
Chronic SVT may be asymptomatic due to the formation of collateral vessels.
The presence of splenomegaly or esophageal varices is a sign of portal hypertension associated with chronic SVT.
Acute SVT is associated with signs of symptoms of up to eight weeks duration.
Early diagnosis through imaging, like abdominal ultrasound or computed tomography scans, and prompt anticoagulation therapy are required.
Abdominal veins bring blood lacking oxygen from the abdomen to the inferior vena cava, draining to the right atrium.
Abdominal organs have 2 venous systems: the systemic one, which drains directly to the inferior vena cava, and the portal one, which drains to the hepatic portal vein and then to the inferior vena cava through the liver.
The systemic venous system includes common iliac, lumbar, renal, right testicular/ovarian, right suprarenal, inferior phrenic, and hepatic veins.
The portal venous system includes right and left gastric, cystic, para-umbilical, splenic, inferior mesenteric and superior mesenteric vein.
The splenic and superior mesenteric merge to form the portal vein.
Blood clots in these venous systems can lead to splanchnic venous thrombosis, and includes thrombosis in the splenic, mesenteric, portal, or hepatic veins.
The most common site of venous thrombosis is a portal and mesenteric vein, with the least common being the hepatic vein.
Left-sided portal hypertension results from complete obstruction of the splenic vein.
Splenomegaly may be detected on imaging.
Typical signs of portal hypertension, include gastroesophageal varices, ascites, and splenomegaly, similar to hepatic disease.
Complications of splanchnic venous thrombosis include gastrointestinal bleeding, esophageal or gastric varices, intestinal ischemia, anemia, thrombocytopenia, and infection.
The incidence and prevalence of splanchnic vein thrombosis are on the rise, attributed to the widespread use of computed tomography that picks up this disease.
The most common leading cause of portal vein thrombosis is liver cirrhosis, with ultrasound showing a prevalence of 5% to 24% for portal vein thrombosis.
Autopsy studies of patients who died of cirrhosis have reported a prevalence of 6% to 64%.
The prevalence of portal vein thrombosis unknown in individuals who are non-cirrhotic is unknown.
Chronic pancreatitis is the most common reason for splenic vein thrombosis.
Splenic vein thrombosis is reported in 5% to 22% of patients with chronic pancreatitis.
Gastric variceal bleeding is the initial presentation in between 45% to 72% of patients with splenic vein thrombosis.
Acute mesenteric venous thrombosis is the cause of acute mesenteric ischemia in 2% to 10% of the cases.
Of all cases of mesenteric venous thrombosis, only 24% to 40% were chronic mesenteric venous thrombosis.
Chronic mesenteric venous thrombosis is noted less than acute thrombosis because of lower incidence or a lack of symptoms.
Chronic mesenteric venous thrombosis incidence rate of 2.2 and 2.0 per million in women and men, respectively.
In contrast, hepatic venous thrombosis is more common in men than in women in Asian countries.
Sudden abdominal pain is the most common presentation of acute splanchnic venous thrombosis, while pain is absent in most cases of chronic venous thrombosis.
Chronic cases present mostly with upper gastrointestinal bleeding secondary to varices.
Patients with acute portal vein thrombosis usually present with severe abdominal pain and nausea in the absence of endoscopic findings.
Chronic cases can have esophageal or gastric varices, which can lead to gastrointestinal bleeding.
Splenomegaly, ascites, and palmar erythema are common in such cases.
Portal vein thrombosis can also be asymptomatic and can be discovered incidentally when a patient undergoes abdominal imaging for any other reason.
Portal vein thrombosis can compress bile ducts and cause biliary symptoms due to cholangiopathy and present with fever, pruritus, jaundice, and right upper quadrant abdominal pain.
Portal vein thrombosis usually has regular liver function tests, hyperbilirubinemia and increased alkaline phosphate levels can be present in cholangiopathy patients.
Splenic vein thrombosis presents in most cases with gastric varices.
If there are gastric varices are present but no esophageal varices, or if gastric varices are more prominent than esophageal varices, then splenic vein thrombosis should be suspected.
Patients with splenic vein thrombosis can be asymptomatic or can present with symptoms that include abdominal pain, variceal bleeding, splenomegaly, and thrombocytopenia.
Acute mesenteric venous thrombosis can lead to mesenteric ischemia and intestinal infarction, which presents with sudden periumbilical abdominal pain out of proportion to the clinical exam.
Abdominal distention might be present on physical exam, and an occult blood test may be positive.
Subacute mesenteric venous thrombosis can ensue when venous thrombosis is present, but there is also partial compensation through collateral vessels that allow for some circulation.
Subacute thrombosis can last days to weeks before any symptom is present.
Subacute thrombosis the most common presentation is nonspecific abdominal pain.
Chronic mesenteric thrombosis is usually asymptomatic and found accidentally on abdominal imaging.
Acute hepatic venous thrombosis presents with fever, abdominal pain, and jaundice, with or without hepatic encephalopathy.
15% to 20% of patients with subacute or chronic hepatic venous thrombosis are asymptomatic.
In chronic cases, symptoms occur when the patient is cirrhotic.
These symptoms include palmar erythema, spider angioma, ascites due to portal hypertension, and esophageal varices.
SPVT associated with decreased survival in patients with cancer.
Portal vein thrombosis has been reported in about 20 to 30% of patient hepatocellular carcinoma at the time diagnosis and is an independent predictor of poor survival.
Thrombotic events may occur in multiple segments or in isolated parts within the splanchnic vasculature: isolated portal vein thrombosis is the most common.
Thrombosis in multiple segments is associated with a significant decreased 10 year survival compared with isolated segment thrombosis.
With mesenteric vein thrombosis a 30 day mortality rate of 20% occurs.
Thrombosis in the mesenteric veincan lead to intestinal infarction, which is life-threatening.
Intestinal infarction has been reported in 30 to 45% of these patients at the time of diagnosis of which up to 19% were fatal.
Risk factors for SPVT include recent abdominal surgery, abdominal mass, cancer, abdominal cancers, pancreatitis, cirrhosis, PNH, myeloproliferative disorders, and JAK2 mutations with or without myeloperforative disorders, exogenous estrogen use such as oral contraceptives or hormone replacement therapy.
Computed tomography (CT) is the diagnostic method of choice in splanchnic vein thrombosis.
In portal vein thrombosis, Doppler ultrasound shows hyperechoic material in the portal vein.
It could show a decrease or even no flow to the portal vein.
The mesenteric or splenic veins can also be enlarged since they merge to make the hepatic portal vein.
Diagnosis includes evaluation with the history and physical exam laboratory testing, and imaging consisting of a CBC, PT, aPTT, metabolic profile, hepatic profile, serum, lactate levels imaging with ultrasound, CT of the abdomen and pelvis, and abdominal MRI.
If portal vein thrombosis is strongly suspected, it is best to start with a CT scan or MRI of the abdomen (CT scan is preferred over MRI).
CT scan of the abdomen shows a thrombus as a densely packed vein.
CT scan may show other pathology that might be present such as a cancerous tumor.
Angiography considered when planning shunt surgery.
Doppler ultrasound is the best initial diagnostic test in cases with a suspicion of splenic vein thrombosis.
A normal splenic vein Doppler makes diagnosing splenic vein thrombosis highly improbable.
In mesenteric venous thrombosis, study results have shown that a CT scan of the abdomen has 90% accuracy.
In cases where a CT scan is nondiagnostic, it is suggested to do CT angiography.
Magnetic resonance (MR) venography is the most reliable imaging for mesenteric venous thrombosis, however most cases can be seen on a CT scan without MR venography.
Doppler ultrasound diagnoses hepatic venous thrombosis, and a CT scan of the abdomen or MRI confirms it.
An upper endoscopy is needed in cases of hematemesis or upper gastrointestinal bleeding, as an endoscopy checks and confirms variceal bleeding.
Patients with portal vein thrombosis and cirrhosis are monitored for varices.
Treatment:
Treating the underlying cause, the thrombosis itself, and the complications that it causes, such as variceal bleeding is paramount.
Treating symptomatic splanchnic venous thrombosis with systemic anticoagulation improved survival and lowered recurrence. : asymptomatic patients should not be treated.
About 25% of splanchnic vein thrombosis cases present with gastrointestinal bleeding at diagnosis, usually from esophageal varices.
Patients with cirrhosis with portal vein thrombosis benefits from anticoagulation therapy, with a lower rate of variceal bleeding.
However, study results have not shown an increase in episodes of bleeding after anticoagulation therapy.
Low molecular weight heparin (LMWH) is the drug of choice for anticoagulation.
Splanchnic vein thrombosis cases have an increased risk of gastrointestinal bleeding, and therefore, LMWH (with a shorter half-life than warfarin) is the preferred medication.
22% to 27% of patients with splanchnic vein thrombosis have underlying solid malignancy.
All patients with splanchnic vein thrombosis should probably be anticoagulated for at least 3 months, but hypercoagulable states require more extended periods of treatment.
Studies using direct oral anticoagulant medications (dabigatran etexilate, rivaroxaban, apixaban, and edoxaban) in splanchnic vein thrombosis, showed an increased risk of gastrointestinal bleeding as compared to LMWH.
Furthermore, the use of direct oral anticoagulants is contraindicated in patients with an underlying liver impairment since their metabolism is through the cytochrome P (CYP)3A4 system.
With symptomatic splenic vein thrombosis, splenectomy is the best treatment.
Patients with cirrhosis and portal vein thrombosis need screening for esophageal varices, even in the absence of bleeding; via upper endoscopy to prevent future variceal bleeding.
Morbidity and mortality of splanchnic vein thrombosis have improved over the years with treatment, due to earlier diagnosis and treatment of the condition.
In a study that followed patients with chronic portal vein thrombosis for 5 years, results showed fewer than 5% of patients died of complications of thrombosis, such as gastrointestinal bleeding.
The mortality rate is higher in patients who have mesenteric vein thrombosis in addition to portal vein thrombosis.
Results from a study of patients with mesenteric vein thrombosis showed the mortality rate was 44% compared to a 66% mortality rate in arterial mesenteric thrombosis.
The mortality rate is higher in patients with intestinal infarction.
Some of the complications of splanchnic venous thrombosis include gastrointestinal bleeding, esophageal or gastric varices, intestinal ischemia, anemia, thrombocytopenia, and infection.
The Budd-Chiari syndrome, hepatic venous thrombosis, is the least common manifestation of splanchnic venous thrombosis, with an incidence of 0.5 to 1 case per million people per year .
They most common sites of splancnic vein thrombosis are the portal vein (77%) and the mesenteric vein (44%).
Splanchnic venous thrombosis causes intestinal infarction distinct from mesenteric arterial occlusion.
Mesenteric venous thrombosis accounts for 5% to 15% of all intestinal ischemic events.
Etiology of splanchnic venous thrombosis is divided into localized and systemic causes.
Local causes include: cirrhosis, solid cancer such as hepatocellular carcinoma or gastric and pancreatic adenocarcinomas, inflammatory disorders of the abdomen such as inflammatory bowel disease and diverticulitis, and abdominal surgery.
Systemic causes include inherited and acquired thrombophilic conditions: Inherited factors may include the factor V Leiden mutation and the prothrombin gene mutation 20210A; acquired thrombophilic causes include myeloproliferative neoplasms especially with positive JAK2 mutation, the antiphospholipid antibody syndrome, paroxysmal nocturnal hemoglobinuria, hormonal therapy, and abdominal malignancy.
Idiopathic splanchnic thrombosis accounts for about 15% to 27% of cases.
The most common local causes are liver cirrhosis (27.8%) and solid cancer (22.7%.
Myeloproliferative neoplasms are the leading systemic cause of splanchnic thrombosis.
Factor V Leiden is more associated with Budd-Chiari syndrome while the prothrombin gene mutation has a stronger association with portal venous thrombosis.
Clots seen in larger vessels are usually due to intra-abdominal causes.
With thrombophilic the thrombosis often begins in smaller vessels and progresses to involve larger vessels.
The most prominent feature of mesenteric ischemia, of arterial or venous type, is abdominal pain out of proportion to the physical exam.
Splanchnic venous thrombosis can be acute, subacute, or chronic.
With acute splanchnic venous thrombosis, abdominal pain begins suddenly and is associated with a risk of bowel infarction and peritonitis.
The subacute form of splanchnic venous thrombosis is characterized by abdominal pain lasting for days to weeks without bowel infarction.
Pain in acute and subacute thrombosis is mid-abdominal and colicky.
With acute Budd-Chiari syndrome there is an associated ascites and hepatic necrosis.
Patients with chronic splanchnic venous thrombosis may not exhibit pain, but develop extensive venous collateral circulation, and are at risk for complications such as bleeding esophageal varices.
Patients with chronic splanchnic venous thrombosis can develop fever, guarding, and rebound tenderness and progress to bowel infarction and peritonitis.
An abdominal CT scan is the best test for diagnosing splanchnic venous thrombosis.
Abdominal CT findings include: acute thrombus will appear as a central lucency in the mesenteric vein, and enlargement of the superior mesenteric vein.
If abdominal CT or MRI reveal developed collateral circulation in the mesentery and retroperitoneum, the thrombosis has been present for more than a few weeks.
Ultrasound usefulness in splanchnic venous thrombosis is limited by overlying bowel gas.
Doppler ultrasound has a sensitivity of about 90% for the diagnosis of Budd-Chiari syndrome and portal venous thrombosis.
Anticoagulation is recommended for all patients with splanchnic venous thrombosis for at least 3 months.
Longer treatment is proposed in patients with permanent thrombotic conditions and a low bleeding risk.
Extended anticoagulation is recommended for cancer-associated thromboembolism.
Anticoagulation for patients with acute portal venous thrombosis and Budd-Chiari syndrome is recommended for at least 3 months.
Where permanent risk factors or clot extension into the mesenteric veins exist, patients should receive anticoagulation indefinitely, as with patients with Budd-Chiari syndrome.
Thrombolytic therapy is for patients with severe symptoms, such as mesenteric venous thrombosis with ischemia, and a low risk of bleeding .
Direct oral anticoagulant drugs have the potential to make splanchnic venous thrombosis treatment easier.
The risk for both thrombosis recurrence and bleeding is higher in patients with portal venous thrombosis than in patients with isolated mesenteric venous thrombosis.
Anticoagulation therapy may improve survival, decrease the recurrence rate, and improve recanalization.
The recanalization in portal venous thrombosis may prevent subsequent development of portal hypertension.