Introduction

Overview about Deep-Vein Thrombosis (DVT)

 

DEEP VEIN THROMBOSIS (DVT) happens when a blood clot is formed in veins located deep inside the body. Deep veins are located within muscle groups whereas superficial veins are located closer to the skin. Mostly, these clots occur in the lower limbs (legs), pelvic region and the thighs. They can also be found in other body areas such as in the arms, brain and liver.

The blood clot, otherwise known as thrombus, develops due to injury to the vein or slow movement of blood through the veins. The blockage may be partial or complete.

This condition is also referred to as venous thrombosis.

DVT as itself is not a life-threatening condition. However, the thrombus may break free and get carried through the bloodstream to other body regions such as the lungs. When in the lungs, these lodge in the vessels of the lung leading to a condition called pulmonary embolism (PE).

Being a serious and life-threatening, pulmonary embolism requires very early diagnosis and correct strategies for treatment.

 

 Key Facts & Statistics

Key facts and statistics that surround DVT

• DVT is a medical condition with complications that are life-threatening. Early treatment can help in prevention of these serious complications.
• Each year in the United States of America about 1-3 persons in every 1,000 individuals develop DVT or pulmonary embolism (PE). A total of 300,000 persons perish yearly due to DVT or PE.
• In the United Kingdom, 1 person in every 1,000 individuals are affected per year.
• The yearly incidence of DVT is 80 cases per 100,000. DVT in the lower limb has a prevance of 1 case per 100,000.
• After heart attacks and stroke, DVT is ranked as the third most common vascular disease.
• Anatomical location affects the rate of involvement of a particular site:

1.  Distal veins – 40%
2. Popliteal vein- 16%
3. Femoral vein- 20%
4. Common femoral vein- 20%
5. Iliac veins- 4%

 

Risk Factors & Causes

What are the risk factors for DVT?

• Obesity. Being excessively overweight (BMI ranging between 25-29.9) or morbidly obese (BMI >40) can predispose an individual to DVT.
• Age. Being older than 60 years. However, DVT can occur in persons of any age. 0nly 1 in 10,000 persons aged younger than 20 years get DVT as compared to 100 in 10,000 (1 in 100) aged above 80 years.
• Smoking. Consumption of tobacco products increases risk for DVT.
• Taking medications such as oral contraceptive pills (OCPs) or receiving hormone replacement therapy that have oestrogen.

• Anatomical variations is anatomy of the veins can lead to thrombosis.
• Having health conditions such as cancer or heart failure. Cancers such as pancreatic and lung cancer increase the risk for DVT, especially if the individual is receiving chemotherapy.
• Having varicose veins.
• Placement of a central venous catheter or pacemaker.
• Family history of blood clots.
• Recently conducted surgical procedures. These include hip and leg surgery.
• Fractures in the hip.
• Polycythemia vera. This is a blood condition characterized by higher than normal haemoglobin levels due to production of excessive blood cells by the bone marrow.
• Being sedentary. Bed rest or excessive sitting (such as during long  journeys in a plane or on the bus ) is a risk factor for DVT. Immobilization limits blood flow in the deep veins.
• Pregnancy or childbirth that occurred within the previous 6 months. Expectant women have a 5- to 10-fold increased likelihood of developing DVT.
• Presence of autoimmune conditions such as lupus and inflammatory bowel disease (IBD).

 

 Signs & Symptoms

What are the signs and symptoms of DVT?

•  Swollen legs.
• Red, discolored or white skin.
• Tachycardia.
• Pain in the legs when walking.
• Warm skin.

 

Pathophysiology

What are the main mechanisms of pathophysiology involved in DVT?

As stated under Virchow’s Triad, they are:

•  Damaged endothelium (vessle wall).
• Blood flow turbulence.
•  Hypercogulability.

 

 Diagnostic Procedures  & Tests

How is DVT diagnosed?

• A physical examination is performed by the clinician.
• Patient history must be reviewed.
• In addition to these, imaging tests can also be conducted. They include:

1.  Duplex venous ultrasound.
2. Venography.
3. Magnetic resonance venography (MRV).
4. Computed tomography (CT) scan.

 

Blood tests. Special blood tests can be conducted:

• For persons from families with history of blood clots.
• For individuals who have a family history of a genetic blood clotting disorder.
• If the patient has clots in an unusual area such as the liver.
• If the history of blood clots cannot be linked to other causes.

 

D-Dimer blood test is used to rule out PE. D-dimer is a kind of protein that blood clots produce. Mostly, there are raised levels of D-dimer in almost all persons with venous thrombosis.

Further discussion on imaging tests;

• Duplex venous ultrasound. This is a non-invasive and majorly available procedure for diagnosis of DVT. It is also the most commonly utilized procedure for DVT diagnosis. Blood flow and any thrombus in the veins are shown by used of ultrasound waves.
• Venography. It is an invasive procedure which is used rarely in these times. Using a catheter, a dye (contrast material) is injected into the veins of the neck. It is used for viewing any blood clots that block venous blood flow, whether partial or complete blockage.
• Magnetic resonance venography (MRV). it is used to view images of the veins in specific parts of the body.
• Computed tomography (CT) scan. This is a form of X-ray that shows internal body structures. It can be used to identify blood clots in the lung, brain and abdomen.

 

 Treatment and Management

How is DVT treated?

The aims of  DVT treatment are to:

• Prevent the clot from becoming larger.
• Prevent breaking off in the vessel and travelling into lungs.
• Lower the risk or chance of development of another deep vein thrombus.
• Prevent chronic complications such as chronic venous insufficiency that could be caused by the clot.

 

DVT drugs include:

• Anticoagulant agents. These are also referred to as blood thinners. Basically, they make it harder for clotting to occur (block clotting). they also prevent these clots from getting larger or moving away. Types of anticoagulants include warfarin, heparin and oral Xa inhibitors.
• Thrombolytic agents. These class of drugs breaks down  blood clots. They are also called busters and are used for in more serious kinds of DVT or PE. They are administered directly into the clot through a catheter.

 

Other strategies include:

• Using filters. For persons unable to take blood thinners,  a filter placed into the inferior vena cava in the abdominal region prevents clots that break off from getting lodged in the lungs.
• Compression stockings. These are also called support stockings, and play a role in prevention of blood-pooling within the legs.

 

Differential Diagnosis

What are the differential diagnoses of DVT?

• Trauma.
• Venous or lymphatic obstruction.
• Peripheral edema.
• Post-thromootic syndrome.
• Cellulitis.
• Vasculitis.

 

 Complications

What are the complications of DVT?

• Pulmonary embolism (PE). blood clots can breakdown, travel within the blood to the lungs where they get lodged.
• Post-thrombotic syndrome. It is characterized by chronic signs and symptoms such as welling and pain in some people who have suffered from DVT.
• Bleeding from the utility of anti-coagulant drugs.

 

Prevention

How do we prevent DVT?

 

Embrace lifestyle modifications such as:

• Consuming healthy, well-balanced diets.
• Perform physical activities. Exercise regularly by jogging, running, walking or swimming.
• Avoid consuming tobacco products, for example through smoking cigarettes.
• Stay hydrated. Properly hydrated blood flows easily and strain on the veins is prevented. However, in dehydration the blood becomes more vsicous and the risk for formation of clots is raised.