What is Inferior Vena Caval Thrombosis?
Inferior vena cava (IVC) thrombosis, a disease associated with high illness rates, is when a blood clot forms in the major vein carrying blood from your lower body back to your heart. Although it’s considered a rare condition, case studies show that it might not be diagnosed as often as it should be. For instance, blood clots in the lungs, or pulmonary embolisms, are usually thought to come from a clot in a deep vein in the lower leg. However, there have been cases where the lung clot was actually caused by an IVC thrombosis.
Thus, if a patient is at risk for a blood clot traveling to other parts of the body (a condition called a thromboembolic event), the possibility of IVC thrombosis should be considered by doctors. Once an IVC thrombus is identified, the doctors will work to figure out the cause, as there could be many possible reasons. For example, some people may have a condition that makes their blood clot more easily.
What Causes Inferior Vena Caval Thrombosis?
Virchow’s triad is a concept that can help us understand why someone might experience a blockage, or thrombosis, in the large vein that carries blood from your lower body back to your heart (known as the inferior vena cava or IVC). This concept states that a thrombosis can occur due to three main factors: slow blood flow, damage to the lining of a blood vessel and an increased tendency for blood to clot (hypercoagulability).
We can classify the causes of an IVC thrombosis into two main groups:
1. IVC Thrombosis in a Normally Developed Inferior Vena Cava
In cases where the IVC has developed normally, thromboses usually form because of pressure from nearby body parts. Examples of these include kidney tumors, pancreatic cancer, large uterine fibroids, and others. Additionally, some people might be more likely to develop blood clots because of certain genetic conditions like thrombophilia or the factor V Leiden mutation. Life choices such as taking oral contraceptives, smoking, having too much weight, being pregnant, or taking hormonal replacement therapy can also increase the risk. To prevent blood clots, some people might have a filter placed in their IVC, but this actually can also cause an IVC thrombosis. Lastly, trauma or injury can also cause an IVC thrombosis.
2. IVC Thrombosis in an Abnormally Developed Inferior Vena Cava
Sometimes, people are born with an IVC that is not formed as usual. This leads to an irregular flow of blood, increasing the chance of a thrombosis forming. Although abnormal IVCs occur in about 1% of the population, within that group, about 60 to 80% develop an IVC thrombosis. The exact location of the clot depends on what the particular abnormality is. For example, this could include having a duplicate IVC, not having an IVC below the kidney, or an additional vein from the left kidney, which can all lead to a formation of a clot.
Risk Factors and Frequency for Inferior Vena Caval Thrombosis
The number of cases of IVC thrombosis, a type of blood clot in the large vein in the middle of your body, is hard to pinpoint. This is because the symptoms can vary a lot from person to person. Of the people diagnosed with deep venous thrombosis, another type of blood clot, it’s reported that 4-15% also have IVC thrombosis. However, the actual number might be higher because the different symptoms make it hard to identify. For instance, people diagnosed with lung blood clots might have IVC thrombosis that hasn’t been diagnosed because no one suspected it and therefore didn’t do the right tests to identify it.
Signs and Symptoms of Inferior Vena Caval Thrombosis
Inferior vena cava (IVC) thrombosis, a condition where a blood clot forms in the IVC, can show different symptoms depending on where the clot is and how big it is. Common symptoms include feeling of heaviness in the legs, pain, swelling, and cramping. Less specific symptoms might include abdominal, flank, or back pain, and men may experience scrotal swelling. These unclear symptoms can sometimes mean the condition isn’t diagnosed until the clot moves to the lungs or kidney veins, both of which can create other symptoms like shortness of breath or decreased urine output. If both legs are swollen or if someone has enlarged superficial veins on their abdomen, that might indicate they have an IVC thrombus. However, because the symptoms can be so broad, it is often hard to definitively diagnose IVC thrombosis just based on patient history and physical exam findings.
- Feeling of heaviness in the legs
- Pain
- Swelling
- Cramping
- Abdominal, flank, or back pain
- Scrotal swelling in men
- Shortness of breath
- Decreased urine output
- Swelling in both legs
- Enlarged superficial veins on the abdomen
Testing for Inferior Vena Caval Thrombosis
There aren’t currently any official guidelines to help in identifying and treating a condition called IVC thrombosis. However, there are several ways doctors can look for it if they suspect it. These include methods like ultrasound, CT scans, MRI scans, and catheter venography.
IVC duplex ultrasound is a type of ultrasound scan that can help to identify a potential blood clot. However, this method has some limitations. For instance, it might be hard to see clearly if the patient is obese or if there’s gas in the intestines. But because it’s a low-risk method, it’s often considered as a starting point. There have been cases reported where IVC thrombosis was identified through ultrasound in emergency situations. Some signs that doctors look for on the ultrasound can include changes in the blood flow pattern, a “choppy” sign which means increased blood speed, and not being able to squeeze the blood vessel.
CT scans can also help to locate the blood clot. However, for most reliable results, an MRI scan is usually the best option as it can see clearly both the clot and how much space it covers. However, because MRIs aren’t always available and can be expensive, they usually aren’t used as the first option. The most common way to confirm a diagnosis is through catheter venography, a method that involves inserting a thin, flexible tube into your veins.
Once the blood clot is diagnosed, your doctor might also want to check for any potential complications that could result from the IVC thrombosis. For example, about 12% of patients with an IVC thrombosis will develop blood clots in the lungs, also known as pulmonary emboli. In this case, a dedicated CT scan of the chest may be needed to check for these. If your doctor is worried about kidney involvement, they may use a nuclear kidney scan to see if there’s any blood flow problems to your kidneys.
Treatment Options for Inferior Vena Caval Thrombosis
The first step in treating a blood clot, also known as an IVC (inferior vena cava) thrombus, usually involves giving the patient a medication that helps prevent more clots from forming. This type of medication is called an anticoagulant.
In the emergency department, doctors might give the patient a medicine called heparin, a type of anticoagulant. The goal is to eventually switch the patient to warfarin or a newer generation anticoagulant, which are types of medications that also help prevent clots.
There are also other treatment options available, depending on how old the clot is. If the clot is new (less than 14 days old) or somewhat new (15 to 28 days old), and the patient doesn’t have a high risk of bleeding, doctors might consider removing it with a catheter, a flexible tube that can be threaded through the body to the clot. This is called catheter-directed thrombolysis or thrombectomy.
Sometimes doctors might consider a treatment known as percutaneous transluminal angioplasty, which involves inserting a small balloon inside a blood vessel to help improve blood flow, and then placing a stent to keep the blood vessel open. If the clot is more than 28 days old, this treatment might be more effective than trying to remove the clot with a catheter.
It’s important to start giving heparin as soon as possible when a patient comes into the emergency department with an IVC thrombus. Doctors will also speak with a vascular surgeon to discuss other possible treatment options.
If the clot has been caused by something from outside the blood vessel, like a tumor, then more tests will be needed to figure out the best way to treat it.
What else can Inferior Vena Caval Thrombosis be?
When a patient is suspected of having IVC thrombosis, there are many different conditions that doctors might consider as part of their diagnosis. These could include:
- Kidney stones (nephrolithiasis)
- Kidney cancer (renal cell carcinoma)
- Pancreatic cancer
- Deep vein thrombosis (DVT)
- Liver disease
- Spinal pathology
- Blood clots in the lungs (pulmonary emboli)
- Bowel obstruction
- Difficulty emptying the bladder (urinary retention)
What to expect with Inferior Vena Caval Thrombosis
The overall outcome depends on what specifically caused the blood clot, or thrombus. If a patient has a hereditary disease that makes their blood clot more easily, they are more likely to develop blood clots. However, if they regularly take their blood-thinning medication as directed, their outlook should be good. On the other hand, if the patient is diagnosed with a rapidly advancing cancer, like pancreatic cancer, that has spread and is putting pressure on the large vein in the abdomen (the inferior vena cava or IVC), their outlook may not be as good.
Children who have had a procedure known as catheterization have developed swelling and ongoing pain in one leg. Lastly, there’s the possibility that the blood clot may break loose and move to the lungs, causing a blockage (a condition known as a pulmonary embolism) if the inferior vena cava has a blood clot that isn’t firmly attached.
Possible Complications When Diagnosed with Inferior Vena Caval Thrombosis
If left unchecked, patients may develop a condition called post-thrombotic syndrome. This leads to changes in venous blood flow, causing sores or ulcers on the lower limbs. Other potential complications include blockages in the lungs known as pulmonary emboli and a decreased blood supply to the kidneys, known as renal ischemia, due to the clot spreading. Therefore, if there’s a suspicion of a clot in the large vein that carries blood from the lower body back to the heart (IVC thrombosis), it’s crucial to not postpone scanning the body for signs of this condition.
Typical Complications:
- Post-thrombotic syndrome resulting in sores or ulcers in the lower limbs
- Pulmonary emboli (blockages in the lung arteries)
- Renal ischemia (decreased blood supply to the kidneys)
Remember, if there’s any suspicion of IVC thrombosis, immediate imaging tests should be done to confirm or rule out the condition.
Preventing Inferior Vena Caval Thrombosis
The key to teaching patients about their health revolves around focusing on those who have risk factors that can be changed. Certain people are at a higher risk of forming blood clots, including those who are overweight, use birth control pills, or have a history of smoking. Teaching these patients about these risks and how to prevent them can make a big difference to their health.
For patients who have a genetic condition like Factor V Leiden, it’s important to discuss the need for ongoing blood thinning treatment. This is done to stop blood clots from forming. Factor V Leiden is a mutation of one of the clotting factors in the blood, which increases the chance of developing abnormal blood clots in veins or arteries.
