What is Splanchnic Venous Thrombosis?
The veins in your belly carry blood from your abdomen back to your heart via a large vein known as the inferior vena cava. Organs in your belly utilize two systems of veins: one is the systemic venous system, which takes the blood straight to the inferior vena cava. The other is the portal venous system, which first carries blood to the liver through a vessel called the hepatic portal vein, then to the inferior vena cava.
The systemic venous system comprises veins from various organs such as common iliac, lumbar, kidney, right testicular or ovarian, right suprarenal, inferior phrenic and liver. The portal venous system includes the right and left gastric, para-umbilical, splenic, inferior mesenteric (via a splenic vein), and superior mesenteric veins. The splenic and superior mesenteric veins merge to form the portal vein.
If a blood clot forms in these systems, it can lead to a condition called splanchnic venous thrombosis. This condition includes blood clots in the veins of the spleen, intestines (mesenteric veins), portal vein, and liver veins (a situation known as the Budd-Chiari syndrome). The most frequent sites for these blood clots are the portal and mesenteric veins, while the least common location is the liver veins. Splanchnic venous thrombosis can cause different symptoms based on where the clot is located.
What Causes Splanchnic Venous Thrombosis?
Left-sided portal hypertension is a condition that involves high blood pressure in the veins leading to and from the spleen, and it typically happens when the main vein of the spleen gets completely blocked. However, this condition doesn’t happen in every case because everybody’s body structure can be different.
Many people with this condition don’t show any symptoms. However, significant enlargement of the spleen might be spotted during medical imaging tests. Some people may also display typical signs of high blood pressure in their spleen and liver, such as swollen veins in the stomach or esophagus, fluid build-up in the abdomen, and an enlarged spleen, which aren’t due to a liver disease.
There can be several complications associated with this condition, such as bleeding in the digestive system, swollen veins in the esophagus or stomach, lack of blood supply to the intestines, low red blood cell count or anemia, low platelet count, and infection.
Risk Factors and Frequency for Splanchnic Venous Thrombosis
Splanchnic vein thrombosis, a type of blood clot that affects veins in the abdomen, is becoming more common. Doctors often discover this issue through computerized tomography scans where they are either searching for something else or confirming their suspicions. A study in Sweden has observed the increase from 2 to 2.7 cases per 100,000 people from the 1970s to the 2000s.
Liver cirrhosis, a disease that impairs the liver’s functions, is a leading cause of this form of thrombosis. From five to twenty-four percent of patients with liver cirrhosis can display signs of this condition during an ultrasound, while autopsies can show symptoms in six to sixty-four percent of deceased patients with cirrhosis. It’s harder to determine how common the condition is in patients who don’t have liver cirrhosis.
In cases of splenic vein thrombosis, another type of blood clot, the most common cause is chronic pancreatitis, a prolonged inflammation of the pancreas. Different studies found this condition in 5 to 22 percent of people with chronic pancreatitis. 45 to 72 percent of cases of this condition initially show symptoms of bleeding in the stomach veins, known as gastric variceal bleeding.
Studies indicate that acute mesenteric venous thrombosis, a sudden blood clot in the intestinal veins, is responsible for two to ten percent of cases of sudden intestinal discomfort, or acute mesenteric ischemia. Only 24 to 40 percent of cases were chronic or long-term blood clots in the intestine (chronic mesenteric venous thrombosis). This might be less prominent than short term intestinal blood clots due to either a lower number of incidents or the lack of symptoms.
Hepatic venous thrombosis, a blood clot in liver veins, tends to be more common in women in their 30s and 40s in non-Asian countries. But in Asian countries, it’s more common in men. One study in Italy showed that for every million people, 2.2 women and 2.0 men were affected by this condition.
Signs and Symptoms of Splanchnic Venous Thrombosis
Acute splanchnic venous thrombosis, a type of blood clot in the abdominal veins, often results in sudden stomach pain. But interestingly, stomach pain is usually absent in chronic cases of these blood clots. Instead, people suffering from chronic blood clots in the abdominal veins more typically have upper digestive system bleeding due to dilated veins or varices.
When someone has an acute portal vein thrombosis, which is a blood clot in the main vein of the liver, they usually experience severe abdominal pain and nausea without any significant findings from an endoscopy. However, this can change in chronic cases, leading to bleeding in the esophagus or stomach due to varices. Enlarged spleen, fluid collection in the abdomen, and redness in the palms are also common in such cases. However, this type of blood clot can also show up with no symptoms and might only be discovered when a person undergoes an abdominal scan for another reason. Additionally, if the portal vein thrombosis presses against the bile ducts, it can cause symptoms related to bile duct disorders, including fever, itchiness, jaundice, and pain in the upper right part of the abdomen.
The symptoms of splenic vein thrombosis, or blood clots in the vein of the spleen, are most commonly related to gastric varices. Variceal bleeding, abdominal pain, an enlarged spleen, and a low platelet count could be seen in these patients. However, some may not show any symptoms at all.
Sudden severe abdominal pain, often around the belly button and disproportionate to the physical exam findings, is a hallmark of acute mesenteric venous thrombosis, or a blood clot in the mesenteric vein. This could even lead to a lack of adequate blood supply to the intestines and intestinal tissue death. Subacute mesenteric venous thrombosis, where there is partial restoration of circulation due to collateral vessels, typically presents with non-specific abdominal pain, whereas chronic mesenteric thrombosis, which lasts a long time, is usually asymptomatic and may often be found unexpectedly on abdominal scans.
Acute hepatic venous thrombosis, a blood clot in a liver vein, commonly presents with fever, abdominal pain, and jaundice, and in some cases, may lead to hepatic encephalopathy, a disruption of brain function due to liver disease. Surprisingly, 15-20% of people with subacute or chronic hepatic venous thrombosis don’t show any symptoms. For those with symptoms in chronic cases, they usually crop up when the patient develops liver cirrhosis, leading to redness in the palms, spider-like blood vessels on the skin, fluid accumulation due to portal hypertension, and esophageal varices.
Testing for Splanchnic Venous Thrombosis
When it comes to diagnosing splanchnic vein thrombosis, a term for blood clots in the veins that drain blood from your organs, a CT scan is typically the best method. However, if you’re experiencing upper right abdominal pain, doctors usually start with a Doppler ultrasound. This test uses sound waves to visualize the blood flow in your vessels and is less expensive and more comfortable than a CT scan or MRI.
If you might have portal vein thrombosis (a blood clot in a vein that brings blood to the liver), a Doppler ultrasound may reveal thick material in the portal vein and decreased or no blood flow. The veins coming from your intestines or spleen might also be enlarged since they merge to create the portal vein. If a doctor strongly suspects portal vein thrombosis, they might skip the ultrasound and go straight to a CT scan or MRI, with a CT scan being the preferred choice. These scans reveal a thrombus (or blood clot) as a tightly packed vein and can also highlight other potential issues, like a cancer tumor. Another tool doctors might use is an angiogram, which involves injecting dye into the blood vessels to make them easier to see on X-rays. However, this is less common than CT or MRI and is mainly used when planning specific types of surgery.
When there’s suspicion of splenic vein thrombosis (a blood clot in a vein draining the spleen), the best initial test is typically a Doppler ultrasound. If the ultrasound of the splenic vein appears normal, it’s highly unlikely that splenic vein thrombosis is the cause. For mesenteric venous thrombosis (a blood clot in a vein that drains blood from the intestines), a CT scan of the abdomen has shown to be 90% accurate. If the CT scan isn’t conclusive, doctors might recommend a CT angiogram. In some cases, an MRI scan of the veins (MR venography) may be recommended as it’s deemed the most reliable. However, most mesenteric venous thrombosis cases can be diagnosed via a CT scan without MR venography. For hepatic venous thrombosis (a blood clot in a vein that drains blood from the liver), a Doppler ultrasound generally makes the diagnosis, and a CT scan or MRI can confirm it.
In anyone with suspected vein thrombosis, and specifically patients with portal vein thrombosis who don’t have liver disease (cirrhosis), doctors will also want to check for problems with blood clotting.
Lastly, if there’s any indication of vomiting blood or bleeding in the upper part of your digestive system, you’ll need an endoscopy. This test uses a flexible tube with a light and camera to view the digestive tract and can check for bleeding from swollen veins (varices) in the esophagus or stomach. Regular endoscopies may also be necessary in patients with portal vein thrombosis or splenic vein thrombosis to monitor these swollen veins.
Treatment Options for Splanchnic Venous Thrombosis
Treating a condition called splanchnic venous thrombosis involves several steps, all aimed at reducing harm and the risk of death. This process involves addressing the root cause, the blood clot itself known as thrombosis, and any complications it might have caused, such as variceal bleeding, which is bleeding from enlarged veins. There isn’t a one-size-fits-all treatment for this condition. Some small studies have suggested that using blood thinners can lower the risk of additional clots forming and increase survival rates.
The American College of Chest Physicians advises using blood thinners for patients who have symptoms. However, they do not recommend treatment for patients without symptoms. According to one estimate, around 25 percent of people with splanchnic vein thrombosis experience gastrointestinal bleeding when they’re diagnosed. This bleeding often comes from enlarged veins in the esophagus. Therefore, it’s important for a doctor to tailor the treatment to each patient, taking into account the risk of bleeding and the potential benefits of using blood thinners. While active bleeding makes using blood thinners unsafe, having a history of bleeding doesn’t necessarily rule it out.
Research suggests that patients with liver scarring (cirrhosis) who also have a blood clot in the portal vein can benefit from blood thinners; they have a lower rate of bleeding from enlarged veins. However, it isn’t as clearcut if a blood clot in the portal vein exists without liver scarring. Studies have found that blood thinner use in these circumstances doesn’t necessarily lead to an increased rate of bleeding.
A drug called low molecular weight heparin (LMWH) is typically used to thin the blood in patients with splanchnic vein thrombosis. Since this condition increases the risk of gastrointestinal bleeding, LMWH is preferred. It has a shorter duration in the body than another drug called warfarin. Additionally, between 22 and 27 percent of patients with splanchnic vein thrombosis have an underlying solid cancer. LMWH is more often used, and more effective, in these cases than warfarin. Deciding how long to use blood thinners depends on the root cause; if there’s a high risk of bleeding, that might be a reason to stop treatment.
There’s some evidence on using different kinds of blood thinners in treating splanchnic vein thrombosis, but one of these drugs, rivaroxaban, has been found to increase the risk of gastrointestinal bleeding compared to LMWH. Furthermore, these kinds of blood thinners should be avoided in patients who have liver problems since these drugs are metabolized in the liver.
If a patient has clogged the splenic vein and is experiencing symptoms, removing the spleen is the best approach. It’s not clear whether patients without symptoms should have their spleen removed. These patients tend to have a low risk of bleeding and might only need their spleen removed if they start experiencing symptoms.
Patients with liver scarring and a clogged portal vein should be checked for enlarged veins in the esophagus even if they’re not showing signs of bleeding. This is done with an upper endoscopy to prevent future bleeding. If these enlarged veins are found, the patient should receive preventive treatment with drugs called non-selective beta-blockers.
What else can Splanchnic Venous Thrombosis be?
When trying to diagnose splanchnic venous thrombosis, which is a blood clot in the veins of the abdomen, doctors will think about and investigate other possible conditions such as:
- Overexposure to arsenic
- Budd-Chiari syndrome (a rare liver disease)
- Cirrhosis (scarring of the liver)
- Congenital hepatic fibrosis (a rare inherited liver disease)
- Granulomatous hepatitis (a form of liver inflammation)
- Hepatoportal sclerosis (hardening of the liver blood vessels)
- Primary biliary cirrhosis (a progressive disease of the liver)
- Sarcoidosis (an inflammatory disease that can affect multiple organs)
- Schistosomiasis (a disease caused by parasitic worms)
What to expect with Splanchnic Venous Thrombosis
The outcomes and survival rates of patients with splanchnic vein thrombosis, a type of blood clot in the veins of the abdomen, have improved over time partly thanks to early diagnosis and treatment. In research that tracked 136 people with a long-term form of this type of clot, called chronic portal vein thrombosis, over 5 years, less than 5% died from complications related to the clot, like bleeding in the digestive tract.
However, survival rates decrease when patients have an additional clot in the mesenteric vein, a vein that supplies blood to the intestines. Examples are seen in a study tracking 3700 patients with this condition where the mortality rate was 44%, compared to 66% mortality rate in arterial mesenteric thrombosis, which is the clotting of the artery and not the vein.
Unfortunately, patients who also suffer from intestinal infarction, a severe condition where the blood supply to the intestines is cut off, causing tissue death, face even higher mortality rates.
Possible Complications When Diagnosed with Splanchnic Venous Thrombosis
Left-sided portal hypertension happens when the blood flow in the splenic vein, which drains blood from the spleen, is completely blocked. This doesn’t happen in all cases because our bodies have different anatomical variations. A lot of the time, people don’t even know they have it. However, in some cases, tests might show an enlarged spleen.
Some people may have symptoms linked to portal hypertension, including bleeding in the gut and varicose veins in the esophagus or stomach, build-up of fluid in the abdomen (ascites), and an enlarged spleen. These symptoms aren’t related to liver disease.
Complications of splanchnic venous thrombosis, which is a blood clot forming in the blood vessels that drain the spleen, liver, and stomach, can include:
- Bleeding in the digestive tract
- Varicose veins in the esophagus or stomach
- Reduced blood flow to the intestines
- Anemia
- Low platelet count (thrombocytopenia)
- Infections
Preventing Splanchnic Venous Thrombosis
Splanchnic venous thrombosis is a very uncommon health concern. Learning about this condition can be very helpful to patients. In simple terms, splanchnic venous thrombosis involves a blood clot in the veins in the abdomen. If you have this condition, you should understand how to recognize the signs of abdominal pain and when to get medical help.
One way to prevent this condition is by teaching patients about the risk factors involved and encouraging changes in their lifestyle habits, like diet and exercise. In addition, patients should also be knowledgeable about the early signs of this condition, which can help in taking quick action. The more active and responsible you are towards your health, the lower the chances and severity of splanich venous thrombosis can be.
