Deep Vein Thrombosis (DVT)

What is Deep Vein Thrombosis (DVT)?

Deep vein thrombosis (DVT) is a condition where a blood clot blocks a deep vein, usually in the leg, but it can also happen in the arms and even in veins supplying the brain and intestines. This blockage interferes with the normal flow of blood. DVT is a pretty common health problem, having an average yearly occurrence of about 1.6 cases per 1000 people. The formation of this blood clot specifically depends on the anatomical location, with 40% in distal veins, 16% at the back part of the knee (popliteal), 20% in the femoral vein, another 20% in the common femoral vein and 4% in the iliac veins.

DVT usually starts in a deep vein in the calf region and tends to move upwards. It falls under the category of venous thromboembolism disorders and is the third leading cause of death from heart-related diseases, following heart attacks and stroke. Even if a patient with DVT doesn’t develop a lung clot, the reoccurrence of the clot and resulting ‘post-thrombotic syndrome’ are significant sources of illness.

It’s significant to note that DVT is a major medical problem causing most cases of lung clotting (pulmonary embolism). Therefore, it’s critical to diagnose and treat DVT early to prevent serious health problems.

What Causes Deep Vein Thrombosis (DVT)?

Deep vein thrombosis or DVT, is a condition where blood clots form in veins located deep in your body. This can happen due to several risk factors such as:

• Restricted blood circulation: Being immobile for a long time, caused by things like prolonged bed rest, anesthetics, surgeries, stroke, or long flights can affect blood flow.
• Increased vein pressure: This situation can arise from physical constraint or functional issues that hamper vein flow; situations like cancer, pregnancy, vein stenosis (narrowing), or birth defects which resist blood outflow can cause these.
• Damage to the vein: Occurrences like injuries, surgeries, inserted catheters, past DVT, or intravenous drug misuse can harm the veins.
• Thickened bloodstream: Medical conditions like polycythemia rubra vera, thrombocytosis, dehydration can thicken the blood.

Different structures of veins in individuals may also impact the development of blood clots.

The probability of blood clotting can also increase due to:

• Genetic predispositions: Deficiencies in certain anticoagulation proteins or presence of certain gene mutations.
• Acquired conditions: Conditions such as cancer, sepsis, heart attacks, heart failure, inflammation of the blood vessels, autoimmune diseases, digestive system conditions, kidney conditions, burns, usage of oral hormones, smoking, high blood pressure, or diabetes can increase the risk.

Certain lifestyle factors like obesity, pregnancy, being over 60, having surgery, being admitted to intensive care, dehydration, and cancer are established as contributing to the chances of getting DVT and complications related to it, known as VTE.

Obesity may contribute to blood clots in two ways, firstly, by raising the levels of a blood protein called fibrinogen, and secondly, by slowing down blood flow, especially in the lower body. Both these factors impact various blood clotting elements, which can lead to thrombosis, thrombophlebitis, and thromboembolic events, the deadliest of which is pulmonary thromboembolisms (blood clots in lungs), which is the chief cause of death in obese patients.

The risk factors can be divided into three categories based on if they are temporary, constant, or unexpected. Temporary risk factors are surgery with anesthesia, hospitalization, cesarean section, hormone therapy, pregnancy and the period around childbirth, injury to the lower body requiring remaining immobile for more than 72 hours. It’s important to note that being given general anesthesia for more than 30 minutes and staying in hospital for over 72 hours are also classified as temporary risk factors.

Persistent risk factors include active cancers and specific conditions that increase the risk of VTE. These conditions, which make one more susceptible, include systemic lupus erythematosus and inflammatory bowel disease.

When risk factors do not fit in either the temporary or the persistent categories, they are considered unprovoked. For instance, a recent study of 500 participants showed a connection between blood fat levels and lower-body DVT. It found that higher levels of total cholesterol, high-density lipoprotein (HDL-C), and apolipoprotein A1 (ApoA1) were linked with a lower risk of lower extremity DVT. However, higher levels of triglycerides, a type of blood fat, were linked with a higher risk.

Risk Factors and Frequency for Deep Vein Thrombosis (DVT)

Deep-vein thrombosis (DVT) and pulmonary embolism are fairly common health issues that often go unnoticed or undiagnosed. This is primarily because these conditions often show no symptoms and are only discovered during an autopsy. As a result, it is thought that the prevalence of these conditions is often underestimated.

• The yearly frequency of DVT is presumed to be around 80 cases per 100,000 people.
• The existence of DVT in the lower limbs is estimated to be 1 case per 1,000 individuals.
• Every year, in the United States, over 200,000 people develop venous thrombosis, a blood clot in the vein. Of these, 50,000 cases are complicated by a pulmonary embolism, a blockage in one of the pulmonary arteries in the lungs.

DVT is quite rare in children and tends to occur more often in people over 40. As for gender differences, there is no clear agreement on whether DVT is more common in one sex over the other.

In terms of ethnicity, data from the United States suggests that DVT and related complications are more prevalent among African Americans and white people compared to Hispanics and Asians.

Common health conditions related to the occurrence of DVT in hospitalized patients include cancer, congestive heart failure, obstructive airway disease (a blockage in the airway), and patients who are recovering from surgery.

Signs and Symptoms of Deep Vein Thrombosis (DVT)

Acute lower extremity Deep Vein Thrombosis (DVT) is a health condition that can show up differently in different people. Depending on where the blood clot is located in the body, how big the clot is, and how much it blocks blood flow, people could have varying symptoms. Some people might not even have any symptoms, while others might have swelling and blue discoloration that’s so severe it can lead to tissue death (venous gangrene).

• Three types of DVT, depending on where the blood clot is: calf vein (distal), femoropopliteal, and iliofemoral thrombosis. Symptoms get more intense the higher up the clot is.
• Up to 50% of people with DVT might not have clear symptoms
• People who’ve had surgery are more likely to have small, symptomless blood clots
• Symptoms of acute lower extremity DVT can include pain, swelling, redness, tenderness, fever, noticeable surface veins, pain when the foot is flexed, and blue tinges to the skin.
• The most serious form of acute lower extremity DVT is called Phlegmasia cerulea dolens, which is characterized by severe swelling, blue discoloration, and pain due to a complete blockage of a vein.

It can be tough to diagnose DVT based on clinical signs and symptoms alone because they tend to be vague. Conditions like lymphedema, superficial venous thrombosis, and cellulitis might be mistaken for DVT. The most common signs of DVT are calf pain and swelling, but these might not always be present or noticeable.

• In their medical history, patients might report:
  • Pain (50% of patients)
  • Redness
  • Swelling (70% of patients)
• During a physical examination, doctors might find:
  • Limb swelling, which could affect one or both limbs
  • Red, hot skin with dilated veins
  • Tenderness

Testing for Deep Vein Thrombosis (DVT)

The Clinical-Etiology-Anatomy-Pathophysiology (CEAP) classification categorizes certain veins as deep veins. These include veins like the inferior vena cava, common iliac, and femoral, among others.

To investigate if a person potentially has a Deep Vein Thrombosis (DVT), National Institute for Clinical Excellence (NICE) guidelines recommend a few tests. These include a D-dimer test, which is very sensitive but not very specific, a coagulation profile, and a proximal leg vein ultrasound.

Whether you need these tests or not depends on the risk of you having a DVT. The first step is to calculate this risk using the Wells scoring system. If your score is 0 to 1, the risk is low, but if it’s 2 or higher, the risk is high.

In high-risk cases, an ultrasound scan of the proximal leg vein should be done within 4 hours. If the scan is negative, a D-dimer test should be done. If getting a scan within 4 hours is not possible, a D-dimer test should be done first, followed by a scan within 24 hours.

If your DVT Wells score is less than 2 but your D-dimer test is positive, an ultrasound scan should be performed within 4 hours. If that’s not possible, you would get an interim dose of an anticoagulant and a scan within 24 hours. If you are diagnosed with a DVT, treatment is initiated as if there’s a positive ultrasound scan.

Clinical decision rules like the “Pulmonary Embolism Rule-Out Criteria” and the “Wells Criteria” are useful when dealing with a potential DVT case. If a patient meets the criteria, they may not need further testing. Still, if they don’t, a D-dimer test can be useful, especially if there’s a low probability of having DVT.

There are various ways to check for DVT, including diagnostic ultrasound, CT venograms, and point-of-care ultrasound (POCUS). POCUS can be especially handy in urgent cases where access to 24-hour ultrasound may not be readily available. It involves examining two high-probability locations for identifying a DVT: the femoral and popliteal veins.

During POCUS, the patient lies down and the doctor uses a high-frequency linear transducer (a special ultrasound tool) to examine the common femoral vein. If the vein completely collapses under pressure, there is no DVT present.

If no DVT is found but doctors are still concerned, testing may be repeated in a week or two. Alternatively, a D-dimer test could suffice in some cases. It is also typical to evaluate a patient’s coagulation status, blood count, and kidney function.

Treatment Options for Deep Vein Thrombosis (DVT)

Treatment for deep vein thrombosis (DVT) is a balance between preventing further blood clots from causing lung problems, reducing the impact of the disease on the patient, and minimizing chances of developing a condition called post-thrombotic syndrome, which can damage veins and cause leg pain and swelling.

At the core of DVT treatment is something called anticoagulation; you can think of this as thinning your blood to slow down clot formation. Guidelines from the UK’s National Institute for Health and Care Excellence (NICE) typically only recommend this treatment for major cases of DVT, which can possibly lead to lung clots. It’s vital to weigh the possible risks of anticoagulation treatment against the benefits for each patient.

Choice of anticoagulation medication, which help slow down clot formation, depends largely on what caused the DVT:

– For cancer-associated blood clots, low molecular weight heparin (a kind of blood-thinner) and factor Xa inhibitors (clot formation blockers), including rivaroxaban, are typically used. However, doctors may consider stronger anticoagulation in patients with newly diagnosed cancer, extensive blood clots, and cancer treatments causing severe side effects such as vomiting.
– If the preferred treatment is once-daily oral medication, rivaroxaban, edoxaban (both are factor Xa inhibitors), or vitamin-K antagonist (another kind of blood-thinner) can be used.

In patients with liver disease, doctors prefer to use a low-molecular-weight heparin. It’s important to note that direct oral anticoagulants are not recommended if the patient has raised INR levels, a marker of blood thinning. For patients with kidney disease where kidneys don’t efficiently filter creatinine (a waste product), doctor’s usually opt for vitamin-K antagonists. Patients with advanced kidney disease should avoid DOACs and low-molecular-weight heparin.

In patients with significant past coronary heart disease, they can choose between a vitamin-K antagonist, rivaroxaban, apixaban or edoxaban. If a patient has a history of throwing up or bleeding in their stomach or intestines, the preferred treatments would be a vitamin-K antagonist or apixaban.

Unfractionated heparin, another type of anticoagulant, is recommended if there’s a need for clot breakdown treatment. Regarding reversal of clot breakdown therapy, it’s important to remember that reversal agents for oral anticoagulants are not universally available. And since most anticoagulants have the potential to reach a developing baby, low molecular weight heparin is the preferred therapy for pregnant women.

It’s also important to keep treatment duration guidelines in mind:

– Anticoagulation with low-molecular-weight heparin, fondaparinux or unfractionated heparin for patients with kidney failure for 5 days until reaching a certain level of blood thinning.
– Vitamin K antagonists for three months.
– For patients with cancer, it is advisable to use low-molecular-weight heparin for six months.
– For patients with unexplained DVT, vitamin K antagonists may be considered for more than three months.

New blood clot prevention drugs like Rivaroxaban, apixaban, dabigatran, edoxaban, and betrixaban are newer factor Xa inhibitors being used.

Usually, DVT treatment lasts for 3 to 6 months, but recurring episodes may require at least a year of treatment, possibly longer for patients with cancer.

Finally, patients might wear compression stockings to support blood flow, and if blood thinners are contraindicated or not preventing blood clots, an inferior vena cava filter might be used. They’re not recommended as a first option, only for those with high risk factors who can’t use anticoagulation treatment.

What else can Deep Vein Thrombosis (DVT) be?

When a doctor is diagnosing deep vein thrombosis (a blood clot in a deep vein), they need to consider other possible conditions that have similar symptoms. These could include:

• Skin inflammation (cellulitis)
• Post-thrombotic syndrome (specifically conditions like venous eczema and lipodermatosclerosis that occur after a blood clot)
• Ruptured Baker cyst (a fluid-filled cyst behind the knee)
• Injuries (trauma)
• A clot in a superficial vein (superficial thrombophlebitis)
• Buildup of fluid causing swelling (peripheral edema), heart failure, liver disease (cirrhosis), kidney disorder (nephrotic syndrome)
• Obstruction in the veins or lymphatic system
• Abnormal connections between arteries and veins (arteriovenous fistula) and other abnormalities in the blood vessels from birth (congenital vascular abnormalities)
• Inflammation of blood vessels (vasculitis)

It’s crucial for the doctor to contemplate these possibilities and carry out suitable tests to arrive at the correct diagnosis.

Surgical Treatment of Deep Vein Thrombosis (DVT)

People suffering from clinically active cancer face a higher risk of blood clots, hence experts suggest they could benefit from measures to prevent clot formation, also known as thromboprophylaxis. This was strongly supported by findings from a large analysis of 33 studies featuring nearly 12,000 patients. It indicated a decrease in the occurrence of venous thromboembolism (VTE or blood clots) in cancer patients undergoing chemotherapy or surgery, without subsequently increasing episodes of significant bleeding.

Existing care standards from the National Comprehensive Cancer Network (NCCN) endorse the use of specific anticoagulants in hospitalized cancer patients to prevent blood clots. However, there are instances when a mechanical method should be preferred over drug therapy. These include cases where patients are actively bleeding, have low platelet count, evidence of coagulation issues causing bleeding, or have a catheter in the spinal canal. It’s also necessary to refrain from mechanical prophylaxis if a patient has acute deep vein thrombosis or severe arterial problems.

A recent large study questioned whether a longer or standard duration of clot-preventing medicines is most beneficial for cancer patients who have been hospitalized due to acute illnesses. The study found that extending the duration of medication didn’t significantly lower the risk of blood clots but almost doubled the risk of bleeding.

In the context of preventing blood clots in outpatients, it is beneficial for surgical oncology patients who have had pelvic or abdominal surgeries to continue with clot prevention measures up to four weeks after their operation. Aspirin or clot-preventing medicines are recommended for patients with a specific type of bone marrow disease called multiple myeloma on certain medications, assessed on a score known as the IMPEDE VTE. For patients with solid cancers on chemotherapy who have a high risk of developing blood clots, specific anticoagulants have demonstrated success in reducing the incidence of clots in the lung arteries.

A particular type of anticoagulant known as low molecular weight heparin (LMWH) remains the preferred option for managing blood clots connected with cancer. However, care needs to be taken with dosage adjustments for those with impaired kidney function and its usage should be avoided in patients on dialysis. Other possible treatment alternatives include direct oral anticoagulants. The usage of a specific medicine called apixaban was found to be as effective as LMWH in managing cancer-linked blood clots without increasing the risk of significant bleeding.

In emergency situations, clot-dissolving therapy can be used for patients at risk of losing life or limb due to a blood clot in the lungs or a deep vein, taking into account contraindications like brain tumors or spreading, active bleeding, and a past instance of internal brain bleeding. Anticoagulation treatment is recommended for a minimum of three months or until such time the cancer remains a threat. For patients who suffered from a blood clot not related to catheter usage, long-term use of anticoagulation medicines is advised.

It’s crucial to keep assessing the benefits and risks and monitor for any complications in all cases. In scenarios where blood clots are found in specific veins and anticoagulation medicines are not advisable, retrievable filters can be placed in the main vein carrying deoxygenated blood to the heart to prevent lung blood clots. Follow-up care is critical to check when contraindications might have resolved to allow for filter removal and a switch to anticoagulation therapy. For those with a catheter-related blood clot, therapy includes removing the catheter or starting anticoagulation if the catheter needs to stay.

What to expect with Deep Vein Thrombosis (DVT)

Many deep vein thrombosis (DVT) cases can resolve on their own without any complications. However, “post-thrombotic syndrome” can occur in 43% of patients two years after experiencing DVT. This syndrome manifests mildly in 30% of cases, moderately in 10% of cases, and severely in 3% of cases.

The risk of experiencing DVT again is significantly high, with a recurrence rate of up to 25%. Furthermore, death within one month of diagnosis is reported in about 6% of DVT cases, and 12% of cases involving a lung clot, known medically as a pulmonary embolism.

The risk of dying early after a clot in the veins, referred to as venous thromboembolism, is greatly associated with the patient having a pulmonary embolism, being older, having cancer, and suffering from underlying heart disease.

Possible Complications When Diagnosed with Deep Vein Thrombosis (DVT)

The two major complications that can arise from Deep Vein Thrombosis (DVT) are:

• Pulmonary emboli, which can become paradoxical emboli if there’s an atrial-septal defect
• Post-thrombotic syndrome

Another issue is bleeding from the use of anticoagulants, or blood thinners, typically used to treat DVT.

Recovery from Deep Vein Thrombosis (DVT)

Strategies to prevent blood clots in the deep veins (deep vein thrombosis) for hospitalized patients who are at risk usually involve a combination of medicine and physical methods. The medicines that might be used include various types of heparin (a blood-thinning drug), new types of pills called novel oral anticoagulants (NOACs)—like dabigatran and rivaroxaban—and other common drugs such as aspirin or warfarin.

Research suggests that NOACs can effectively prevent blood clots or death related to blood clots when used for extended periods. However, the risk of unwanted bleeding can vary. In this context, Apixaban has stood out as the safest choice when compared to other NOACs, warfarin (and its ideal level of action), and aspirin.

On the physical side, different methods can be used such as:

1. Special compression stockings
2. Devices that regularly squeeze the legs (intermittent pneumatic compression)
3. Devices that create a pumping sensation in the feet (venous foot pumps)
4. Devices that use mild electrical pulses (electrical stimulation devices)

However, it’s important to note that these physical methods should be used in conjunction with medication to prevent blood clots effectively.

Preventing Deep Vein Thrombosis (DVT)

Patients should start to move around as much as possible. In addition to this, they should wear special socks that help improve blood flow called compression stockings. Lastly, quitting smoking is highly recommended because it significantly improves the body’s ability to heal itself.