Ms V had been taking daily oral contraceptive pills after she had an unplanned pregnancy few years earlier. She alighted at the airport after an uninterrupted flight that lasted 17 hours. After obtaining her luggage, she felt a sudden chest pain with difficulty with breathing. Before she could get adequate attention, she slumped and died. An autopsy confirmed blood clots in her thigh and pelvic veins. In the arteries of her lungs were found blood clots. Pulmonary embolism (PE) was the cause of her death.
WHAT IS THROMBOSIS?
Normally, blood flows with ease through the vessels in the body. This is because it is in a liquid state. Due to several causes, the blood constituents may clump together to form a solid mass, called thrombus or blood clot. In the affected part of the blood vessel, the thrombus will obstruct blood flow through the vessel. Thrombosis refers to the entire process involved in the formation of the thrombus. Part of the thrombus may break off, called embolus, to cause further obstruction in distant areas of the body.
Thrombosis can occur anywhere within the body circulation. Asides the blood, the circulation principally comprises the heart (the pump) and blood vessels including veins and arteries. The veins can be superficial (near the skin surface) or deep (within the muscles or surrounding the organs). Formation of blood clot in the deep veins is called deep vein thrombosis (DVT). Predominantly, DVT affects the legs, but can also occur in the pelvic area or arms.
HOW COMMON IS DEEP VEIN THROMBOSIS?
DVT affects hospitalized patients and otherwise healthy persons in their homes. In a number of cases, the blood clot may dislodge in the deep veins of the legs and move to block a major vessel in the lungs, causing a life threatening condition called pulmonary embolism (PE). Hence, DVT is a ‘silent killer.’
According to US Center for Disease Control and Prevention, about 60,000 – 100,000 Americans die of DVT/PE annually. Approximately 10 – 30% of affected people will die within one month of diagnosis.
WHAT CAUSES THROMBOSIS?
The causes may be inherited or acquired. Inherited causes include
- An inherited tendency to have excessive blood clotting, generally termed thrombophilia. There is a genetic basis for the abnormal clot formation in such individuals. Such conditions include Leiden V mutations, Antithrombin deficiency, Protein C and Protein S deficiency and others.
Acquired risk factors are by far the most common. They include
- Increasing age (> 40 years)
- Immobility as in prolonged travel without exercising the legs; bed-ridden states (lasting > 72 hours); immobilizing plaster (POP) casts (lasting > 1 month). This allows for stasis of blood in the legs. Blood components therefore have enough time to interact and form clots.
- Congestive heart failure (lasting > 1 month)
- Acute myocardial infarction (heart attack)
- History of major surgery
- Overweight or obesity
- Use of oral contraceptives
- Cancers (history or present)
- Sickle cell disease
HOW DOES DEEP VEIN THROMBOSIS AFFECT THE INDIVIDUAL?
Most individuals with DVT do not have any complaint. This is because in the early stage, the deep veins are big enough not to have blood flow obstructed in them by the blood clot. However, the usual presentations are
- Pain, tenderness, swelling, warmth, and redness on the affected limb, mostly the leg.
- If the clot had travelled to the lung arteries (pulmonary embolism), features include shortness of breath, rapid breathing, chest pain, rapid heart rate, and light headedness.
- In 25 percent of people having pulmonary embolism, first observation is sudden death. Therefore, there is a need for awareness and prevention.
HOW IS DVT DIAGNOSED AND TREATED?
Diagnosis requires a high index of suspicion due to numerous possible causes. Once there is a clinical suspicion of deep vein thrombosis, laboratory and radiological investigations are done to confirm it.
The treatment involves efforts to achieve anticoagulation ( to antagonize blood clotting). There is also the need to remove the underlying cause or risk factor. Anticoagulation involves
- Making the blood less sticky with medications.
- In some cases, attempt is made to break the formed clots using clot dissolving medications.
- Removal of the blood clot via surgery may be necessary.
- In more challenging cases (where medications or surgery is considered dangerous), blood filters may be placed in the inferior venae cava (a very large vein in the abdomen) to prevent a fatal pulmonary embolism.
HOW IS DEEP VEIN THROMBOSIS PREVENTED?
Everyone is at risk of forming blood clots. It is important to be aware and to prevent its occurrence.
- If you have any symptoms, talk to your doctor about it.
- If you have been planned for surgery, talk to your doctor about prevention of DVT particularly if you have a personal or family history of thrombosis.
- Get up and move around as soon as possible, after being bedridden, after surgery or any major illness or injury.
- If you are travelling for a long period (road or air) exceeding four hours, avoid sitting for long; get up and move around every 2 – 3 hours.
- Maintain a healthy weight and be active. If overweight or obese, ensure weight reduction.
- Take adequate water for proper hydration.
- Avoid cigarette smoking (active or passive).
Dr Adewoyin Ademola is a Nigerian-based Physician with specialization in Haematology. Dr Adewoyin earned his medical degree (MBBS) from the University of Lagos in 2007. Dr Adewoyin is a fellow (by examination) of the faculty of Pathology (National Postgraduate Medical College of Nigeria) and faculty of laboratory medicine (West African College of Physicians). His core competences include clinical/laboratory management of blood and blood related disorders, medical consultations, laboratory leadership/quality and medical research. Professional memberships include Nigerian Medical Association, Nigerian Society of Haematology and Blood Transfusion, American Association of Blood Banks, United States and Canadian Academy of Pathology. He is a Consultant Hematologist in Lagos, Nigeria. He can be contacted via firstname.lastname@example.org.