DVT: recognising a possible clot in the leg

Understanding deep-vein thrombosis

Deep-vein thrombosis (DVT) is a blood clot that forms inside a deep vein, most often in the calf or thigh. Deep veins carry blood back to the heart from the muscles; when a clot partly or fully blocks one, blood backs up behind it, causing the swelling, pain and warmth that bring most patients to see a doctor. Symptoms can closely resemble a pulled muscle, cellulitis (a skin infection) or simple swelling from standing too long, which is why examination and imaging — not self-diagnosis — are needed to tell them apart.

The reason DVT is taken so seriously is not usually the leg itself. A piece of clot can break free and travel through the bloodstream to the lungs, where it lodges in a lung artery — this is called a pulmonary embolism (PE), and it is a medical emergency. Understanding this connection is the single most important thing in this guide.

What DVT feels like in the leg

These are useful clues to discuss with a clinician, not a checklist for diagnosing yourself — DVT cannot be reliably confirmed or ruled out by symptoms alone.

• ●New swelling affecting one leg noticeably more than the other
• ●Calf or thigh pain, tenderness or a cramping ache, sometimes worse when standing or walking
• ●Warmth over the affected area
• ●A change in skin colour — redness or a slight blue or purple tinge
• ●Visibly more prominent surface veins on the affected leg
• ●Occurring after immobility, hospital admission, surgery, pregnancy, long travel, or a previous clot

What causes a clot to form

Clots form when three things combine: blood flow slows down, the vein wall is irritated or injured, or the blood itself clots more easily than usual. Most real-world cases involve more than one of these at once.

Slowed blood flow

Long periods of immobility — after surgery, during hospital admission, on long flights or road journeys, or with reduced mobility from illness — let blood pool in the leg veins rather than being pumped along by muscle movement.

Vein wall injury

Surgery, trauma, or an intravenous line or catheter can irritate or injure the vein lining, creating a surface where a clot can start.

Increased clotting tendency

• ●Pregnancy and the weeks after childbirth
• ●Oestrogen-containing contraceptives or hormone therapy
• ●Cancer and some cancer treatments
• ●Inherited clotting disorders
• ●Dehydration
• ●Some chronic inflammatory conditions

Who is more likely to develop DVT

Risk rises with the number of these present together, and it is worth mentioning any that apply at your appointment:

• ●Recent surgery, especially hip, knee or abdominal surgery
• ●Hospital admission or prolonged bed rest
• ●Long-distance travel by air or road without moving
• ●Pregnancy or recent childbirth
• ●Hormonal contraceptives or hormone replacement therapy
• ●A previous DVT or pulmonary embolism
• ●A family history of clotting problems
• ●Cancer
• ●Obesity
• ●Smoking
• ●Increasing age

What happens if DVT is missed or untreated

The complications of DVT range from serious and immediate to gradual and long-term.

Pulmonary embolism. As above, a piece of clot travelling to the lungs is the most dangerous complication and the reason DVT is never treated as a minor problem.

Post-thrombotic syndrome. Even after treatment, some people develop long-term swelling, aching, heaviness or skin changes in the affected leg because the vein's internal valves were damaged by the clot — a reason early, adequate treatment matters.

Recurrence. Anyone who has had one DVT has a higher chance of another, which is why the underlying cause and the right duration of treatment are carefully considered rather than assumed.

Chronic pulmonary hypertension. Rarely, unresolved clot in the lung arteries causes persistent high pressure in the lung circulation, a serious but uncommon long-term complication.

How Cardiocare confirms or rules out DVT

The right pathway depends on your symptoms, examination and risk factors. It typically draws on some or all of the following:

• 01
  Clinical probability assessment. A structured review of your symptoms, examination findings and risk factors, used to decide how likely DVT is and which test to do next.
• 02
  D-dimer blood test. Measures a substance released when a clot breaks down; a normal result in a low-probability patient makes DVT unlikely, but a raised result does not confirm it — many other things raise it too.
• 03
  Compression ultrasound. A painless scan of the leg veins, and the main test used to directly confirm or rule out DVT.
• 04
  CT pulmonary angiogram or other lung imaging. Used when pulmonary embolism is suspected, to look directly for clot in the lung arteries.
• 05
  Blood testing for an underlying clotting tendency. Considered in selected situations, such as a clot without an obvious trigger, recurrence, or a strong family history.
• 06
  Cancer screening where relevant. An unprovoked clot in an older adult occasionally prompts a search for an undiagnosed underlying illness.

How DVT and pulmonary embolism are treated

Treatment reduces the immediate danger and lowers the chance of recurrence — there is no single treatment; it is matched to the clot's location and your individual risk.

Medicines, by class

• ●Anticoagulants (blood thinners) — the mainstay of treatment; they do not dissolve an existing clot directly but stop it growing and prevent new clots, giving the body's own systems time to break the clot down naturally
• ●Thrombolytic (clot-dissolving) medicines — reserved for selected, more severe cases, such as a large pulmonary embolism causing significant strain on the heart

The duration of anticoagulant treatment varies — often a matter of months, sometimes longer — depending on whether a clear trigger was found and whether it has resolved.

Other measures

• ●Compression stockings — support leg circulation and can reduce swelling and the risk of post-thrombotic syndrome during recovery
• ●IVC filter — a small device placed in the main vein returning blood to the heart, used in specific situations where anticoagulants cannot safely be given; available through Cardiocare's on-site cardiac catheterisation ("cath") laboratory

Living with a DVT diagnosis: everyday self-care

• ✓Take blood thinners exactly as prescribed, at consistent times — missed or extra doses change how well they protect you
• ✓Tell every clinician and dentist you see that you are taking a blood thinner before any procedure
• ✓Watch for unusual bruising or bleeding and report it rather than adjusting the medicine yourself
• ✓Move regularly during long journeys, and mention DVT prevention before any planned surgery or hospital stay
• ✓Stay well hydrated, especially when travelling or in Abuja's heat
• ✓Attend follow-up to review the cause, the planned duration of treatment, and future prevention

Preparing for your appointment

What to bring

• ✓A list of all medicines you take, including herbal and over-the-counter products
• ✓Details of any recent surgery, travel, hospital admission or pregnancy
• ✓Any previous clot history, in yourself or close family
• ✓Your HMO card or payment details

What we will ask

When symptoms started, recent surgery, travel or immobility, medicines including contraceptives, any personal or family history of clots, and whether you have any breathing symptoms.

Questions worth asking us

• ●How likely is it that this is a clot, and what test confirms it?
• ●How long will I need to take a blood thinner?
• ●What symptoms mean I should seek emergency care before my next visit?
• ●Do I need any further tests to look for an underlying cause?