It starts quietly. A little swelling in one leg. Some heaviness, maybe mild pain in the calf. Nothing that seems alarming enough to go to a hospital for.
This is how Deep Vein Thrombosis — a blood clot inside a deep vein of the leg — usually begins. And this is exactly why it is so dangerous.
Because what most patients do not know is that this clot in the leg can break free, travel through the bloodstream, and reach the lungs — where it becomes a Pulmonary Embolism (PE). A pulmonary embolism can block the blood supply to the lungs, strain the heart beyond its limits, and kill within minutes. There is no warning. There is no second chance.
This guide, by Dr. Ashutosh Kumar Pandey — Vascular Surgeon in Lucknow — explains exactly what DVT is, how it progresses to pulmonary embolism, who is at risk, what the warning signs are, and how this condition is treated before it becomes fatal.
Deep Vein Thrombosis (DVT) is the formation of a blood clot inside one of the deep veins of the body — most commonly in the calf, thigh, or pelvis. Unlike the surface veins visible under the skin, deep veins lie within the muscle. They carry the majority of the body's blood from the legs back up to the heart and lungs.
When a clot forms inside these deep veins, blood flow through that segment is partially or completely blocked. This is what causes the classic symptoms of DVT — swelling, pain, warmth, and redness in the affected leg.
But DVT's true danger is not the blockage it causes in the leg. It is what happens when a piece of that clot — or the entire clot — detaches from the vein wall and enters the bloodstream.
Because the deep veins drain back to the heart, any clot that detaches from a leg vein travels directly upward through the venous circulation, passes through the right side of the heart, and then enters the pulmonary arteries — the blood vessels that supply the lungs.
When that clot lodges in the lungs, it becomes a Pulmonary Embolism. And that is where DVT stops being a "leg problem" and becomes a potentially fatal medical emergency.
A Pulmonary Embolism (PE) occurs when a blood clot — most often originating from the deep veins of the leg or pelvis — travels through the bloodstream and becomes lodged in one of the pulmonary arteries, the vessels that carry blood from the heart into the lungs for oxygenation.
When this blockage occurs, two things happen simultaneously:
First, the blocked section of lung can no longer participate in oxygen exchange. Depending on the size and position of the clot, a small, medium, or large portion of the lung becomes non-functional. The patient's oxygen levels begin to fall.
Second, the right side of the heart — which is pumping blood into those now-blocked lung arteries — faces a sudden, severe increase in resistance. The right heart begins to strain. In a massive pulmonary embolism, the right heart can fail completely within minutes — and the patient collapses.
This is why pulmonary embolism can be instantly fatal even in an otherwise healthy, young person. It does not give the body time to adapt. It does not announce itself with days of warning. It can strike in the middle of a normal day — while walking to the bathroom, climbing a staircase, or simply getting up from a chair.
DVT and PE together are classified under the medical term Venous Thromboembolism (VTE) — because they are, in reality, two stages of the same disease process.
Understanding this journey helps explain why time matters so much in DVT Treatment..
Step 1 — A clot forms in the deep vein of the leg. It may be triggered by prolonged immobility, surgery, dehydration, or one of several other factors described below. Initially, the clot may be partially attached to the vein wall.
Step 2 — The clot grows or is disturbed. If untreated, the clot enlarges. Physical activity, especially sudden or forceful movement, can cause a piece of the clot to break away from the vein wall.
Step 3 — The clot fragment enters the circulation. The fragment — now called a thromboembolus — travels upward through the deep veins of the leg, enters the inferior vena cava (the large vein running through the abdomen), and reaches the right side of the heart within seconds.
Step 4 — The clot enters the pulmonary arteries. From the right heart, the thromboembolus is pumped directly into the pulmonary arteries. Here, depending on its size, it either lodges in a large pulmonary artery (massive PE, immediately life-threatening) or travels into a smaller branch (submassive or minor PE, less immediately dangerous but still requiring urgent treatment).
Step 5 — Lung tissue is deprived of blood supply. The affected portion of the lung cannot receive blood, cannot exchange oxygen, and if the clot is not dissolved quickly, that lung tissue begins to die — a process called pulmonary infarction.
This entire journey — from the leg vein to the lung artery — can take minutes. There is no stage at which the patient feels the clot "moving." The first sign is often a sudden and severe deterioration in breathing.
Yes. DVT can and does cause death — through pulmonary embolism.
Here is what the medical evidence tells us:
Not every DVT leads to a pulmonary embolism. Clots that remain in the calf veins without propagating upward carry a lower risk of embolisation. However, clots in the thigh veins (femoral and iliac veins) carry a significantly higher risk of breaking off and causing PE.
In approximately 25% of pulmonary embolism cases, the very first presentation is sudden death — with no prior warning signs that were recognised or acted upon.
The risk of death is highest in patients who have:
The risk of death drops sharply when DVT is diagnosed and treated early — before the clot has the opportunity to embolise to the lungs.
This is the single most important message of this blog: DVT is a treatable condition. Pulmonary embolism is a preventable complication. But only if the patient seeks medical attention before the clot moves.
DVT is not a rare condition that only affects elderly or seriously ill patients. It can affect anyone — including young, otherwise healthy adults. Several risk factors are particularly common in the population of Uttar Pradesh and the surrounding region.
When the leg muscles are inactive for extended periods, blood flow through the deep veins slows significantly. This sluggish flow encourages clot formation. Any period of immobility lasting more than four hours increases DVT risk.
This is especially relevant for:
Surgery — especially orthopaedic surgery (hip and knee replacements, fracture repair), abdominal surgery, and gynaecological surgery — is one of the strongest triggers for DVT. Both the surgical trauma and the period of immobility following an operation activate the body's clotting system.
DVT risk is highest in the first 2 to 10 days after surgery and remains elevated for up to 3 months. Patients who undergo major surgery at hospitals in Lucknow, Kanpur, or Gorakhpur and then return home to their districts for recovery — often without proper anticoagulation guidance — are particularly vulnerable.
Active cancer significantly increases the blood's tendency to clot. Certain cancers — particularly pancreatic, colorectal, lung, and gynaecological cancers — are associated with a very high DVT risk. Patients receiving chemotherapy are at even higher risk.
Pregnancy increases DVT risk by 5 to 10 times compared to non-pregnant women of the same age. The expanding uterus compresses the deep veins of the pelvis, and pregnancy-related hormonal changes make the blood more likely to clot. This risk extends through the first 6 weeks after delivery, making the postpartum period particularly important to monitor.
Excess body weight increases pressure in the leg veins, slows venous return, and is associated with a chronic low-grade inflammatory state — all of which promote clot formation. With obesity rates rising across UP's urban centres including Lucknow, Kanpur, and Varanasi, this risk factor is increasingly relevant.
A patient who has had DVT before has a significantly higher risk of a second episode. Similarly, inherited clotting disorders — such as Factor V Leiden mutation, Protein C or Protein S deficiency — run in families and predispose affected members to DVT, sometimes at a young age. Anyone with a first-degree relative who has had DVT or unexplained pulmonary embolism should discuss screening with a Vascular Doctor In Lucknow..
DVT does not always announce itself loudly. In fact, research shows that up to 50% of DVT cases are "silent" — they produce no obvious symptoms at all. This is one reason the condition is so frequently missed until it has already caused a pulmonary embolism.
When symptoms do appear, they typically affect one leg — not both. This asymmetry is an important clue.
Symptoms to watch for in the leg:
An important point: these symptoms can be confused with a muscle pull, a ligament sprain, or general leg tiredness. Many patients in Gopalganj, Ayodhya, and the surrounding districts come to Lucknow after weeks of treating a "muscle strain" with pain balms — only to find on a Doppler scan that they have had a DVT the entire time.
If you have one-sided leg swelling that appeared without injury, please do not delay. Get a Colour Doppler Ultrasound of the leg as soon as possible.
Pulmonary embolism symptoms can appear suddenly and deteriorate rapidly. They are frequently mistaken for a heart attack or an anxiety attack — which causes dangerous delays in getting the right treatment.
The most common symptoms of pulmonary embolism are:
If any person — whether or not they have known leg symptoms — develops sudden breathlessness, chest pain, or collapses, this must be treated as a medical emergency. Call for help immediately and do not wait.
Pulmonary embolism is often difficult to diagnose because its symptoms overlap with those of heart attack, pneumonia, asthma, and anxiety. A CT Pulmonary Angiography (CTPA) scan is the gold-standard test for confirming PE.
Ramesh Tiwari (name changed with consent), a 44-year-old government clerk from Faizabad Road, Lucknow, noticed swelling in his left leg about ten days after returning from a week-long family visit to Kanpur. The journey had involved an overnight bus ride each way, and he had been sitting for long stretches without moving.
He initially assumed it was a muscle issue and applied a pain relief ointment. When the swelling did not reduce after five days and his calf became tender to touch, his wife insisted he see a specialist. A relative directed the family to Dr. Ashutosh Kumar Pandey at Tender Palm Hospital.
"I honestly thought it was just tiredness from the journey. But when Dr. Ashutosh explained what was happening on the Doppler scan — that there was a clot in my thigh vein — and told me it could have moved to my lungs, I was shocked. I had no idea a swollen leg could be so dangerous."
A Colour Doppler Ultrasound confirmed a proximal DVT in the left femoral vein. Ramesh was started on anticoagulation treatment immediately, admitted for monitoring, and discharged after a few days with a structured plan for continuing blood thinners at home. A follow-up scan at six weeks confirmed the clot had resolved significantly.
"The quick diagnosis saved me from something much worse. I am grateful I did not wait longer."
This experience reflects what Dr. Ashutosh Kumar Pandey sees regularly in his practice — patients who live with an undiagnosed DVT for days or weeks because they do not know what to look for. Early consultation is the difference between a manageable condition and a life-threatening emergency.
📍 If you or a family member have unexplained leg swelling, do not wait.
Diagnosing DVT requires a combination of clinical assessment and imaging. The following are the key tests:
Colour Doppler Ultrasound of the leg: This is the first-line test for DVT. It is non-invasive, involves no radiation, and can be done quickly. It directly visualises the deep veins of the leg, confirms the presence of a clot, identifies its location and extent, and assesses whether blood flow is partially or completely blocked.
D-Dimer blood test: D-dimer is a protein fragment released when a blood clot breaks down. A significantly elevated D-dimer level raises the suspicion of DVT or PE. However, D-dimer alone cannot confirm DVT — it requires imaging for confirmation. It is most useful for ruling out DVT in low-risk patients.
CT Pulmonary Angiography (CTPA): If pulmonary embolism is suspected, a CTPA scan is the gold-standard test. It involves an intravenous contrast injection and a CT scan of the chest, which directly visualises the pulmonary arteries and identifies any clots within them.
Venography: In selected complex cases, a contrast dye study of the veins (venography) may be used to map the extent of clotting — particularly before planning a surgical or endovascular intervention.
Thrombophilia screening: In young patients, patients with recurrent DVT, or those with a strong family history of clotting, blood tests for inherited clotting disorders (thrombophilia screening) may be recommended to identify an underlying cause.
The goal of treatment has three components: stop the clot from growing, prevent it from reaching the lungs, and dissolve or remove the clot that already exists. The approach depends on the location, size, and severity of the DVT or PE, and on the individual patient's overall health.
Anticoagulants — commonly known as blood thinners — are the cornerstone of DVT treatment. They do not dissolve an existing clot, but they prevent the clot from growing larger and significantly reduce the risk of new clot formation and embolisation.
Anticoagulation is typically started immediately once DVT is confirmed. Initial treatment may involve injectable anticoagulants such as Low Molecular Weight Heparin (LMWH) or fondaparinux, followed by or replaced with oral anticoagulants — either the newer Direct Oral Anticoagulants (DOACs such as rivaroxaban or apixaban) or the older warfarin (adjusted using INR monitoring).
Treatment duration is typically 3 to 6 months for a first episode of DVT with an identifiable cause (such as recent surgery or travel), and may be longer or indefinite for patients with recurrent DVT, active cancer, or inherited thrombophilia.
In patients with extensive, proximal DVT — particularly in the iliac and femoral veins — or in patients with moderate-severity pulmonary embolism who are deteriorating despite anticoagulation, catheter-directed thrombolysis may be performed.
In this minimally invasive procedure, Dr. Ashutosh Kumar Pandey guides a thin catheter directly to the site of the clot using live X-ray imaging. Clot-dissolving medication (thrombolytic agent) is then delivered directly into the clot through the catheter — dissolving it far faster and more effectively than systemic (intravenous) medication, while minimising the risk of bleeding complications in other parts of the body.
This technique is particularly valuable in young patients with massive iliofemoral DVT, where rapid clot removal can prevent long-term complications such as post-thrombotic syndrome (chronic leg swelling and pain that can last for years after DVT).
In patients who cannot receive anticoagulation therapy — due to recent surgery, active internal bleeding, or very high bleeding risk — an Inferior Vena Cava (IVC) filter is placed to physically prevent clots from reaching the lungs.
The IVC is the large vein that carries blood from the legs and abdomen back to the heart. An IVC filter is a small, cone-shaped metal device that is implanted inside the IVC through a small puncture — no open surgery required. It acts as a physical barrier, trapping any clot that breaks away from the leg veins before it can reach the pulmonary arteries.
IVC filters can be permanent or retrievable (temporary). Retrievable filters are removed once anticoagulation can be safely restarted. Dr. Ashutosh Kumar Pandey is one of the few vascular surgeons in Lucknow with extensive experience in both IVC filter placement and retrieval using advanced endovascular techniques.
In rare cases — typically massive pulmonary embolism that is immediately life-threatening — surgical removal of the clot (pulmonary embolectomy) or catheter-based mechanical thrombectomy may be required. These procedures are reserved for the most severe cases where other treatments have failed or cannot be used quickly enough, and where the patient is at immediate risk of cardiac arrest.
Untreated DVT does not simply "go away." It has consequences — both immediate and long-term.
Pulmonary Embolism: The most feared and most immediately life-threatening complication, described in detail throughout this blog.
Post-Thrombotic Syndrome (PTS): After a DVT, the damaged vein valves may not recover fully. This leads to chronic venous insufficiency — a condition where blood pools in the lower leg, causing persistent swelling, aching, skin discolouration, and eventually, venous ulcers. Studies show that post-thrombotic syndrome develops in up to 50% of DVT patients within 2 years of their initial clot — and is more common when treatment is delayed or inadequate.
Recurrent DVT: A patient who has had one episode of DVT has a significantly higher risk of developing another — particularly in the same leg. Each recurrent episode carries the same risk of pulmonary embolism.
Chronic Thromboembolic Pulmonary Hypertension (CTEPH): In a small but significant proportion of patients who survive pulmonary embolism, the clots in the pulmonary arteries do not dissolve completely. Over time, they scar and narrow the pulmonary arteries permanently — causing chronically high blood pressure in the lung circulation (pulmonary hypertension) that progressively strains the right heart.
None of these complications are inevitable. All of them are significantly less likely when DVT is diagnosed and treated correctly and promptly.
DVT is a condition that can, in many cases, be prevented — especially in high-risk situations. These steps are particularly relevant for patients living in Lucknow, Kanpur, Gorakhpur, Gopalganj, Ayodhya, and the surrounding districts, where long-distance travel by bus and train is part of everyday life.
On long journeys — bus or train: Get up and walk for at least 5 minutes every 2 hours. While seated, flex and extend your ankles repeatedly — this activates the calf muscle pump and keeps blood moving through the deep veins. Stay well hydrated. Avoid alcohol and excessive tea or coffee, which cause dehydration.
After surgery: If you are scheduled for any major surgery, discuss DVT prevention with your surgeon in advance. Ask whether you need anticoagulant injections or compression stockings during your recovery. Do not remain in bed longer than necessary — begin walking as early as your surgeon permits.
During illness or bed rest: Prolonged bed rest — whether recovering from infection, injury, or any other illness — increases DVT risk. Move your legs regularly even while in bed. Ankle pumping exercises are simple and effective.
If you are pregnant: Discuss your DVT risk with your obstetrician, especially if you have other risk factors such as previous DVT, obesity, or a family history of clotting disorders. Be aware of the warning signs of DVT and PE throughout your pregnancy and in the 6 weeks after delivery.
Maintain a healthy weight: Obesity is a modifiable DVT risk factor. Even a modest reduction in weight significantly reduces venous pressure in the legs.
Stay active: Regular walking and leg exercises improve circulation through the deep veins and reduce the overall risk of clot formation.
DVT and pulmonary embolism do not exist in isolation. Several other vascular and non-vascular conditions are closely linked — either as risk factors for DVT or as conditions that share overlapping symptoms and require specialist evaluation.
Varicose Veins: Patients with significant varicose veins have impaired venous return from the legs, which increases the risk of blood pooling and clot formation. While superficial varicose veins do not cause DVT directly, they are a marker of venous system disease. Read more about varicose veins treatment on our Varicose Veins Treatment page.
Peripheral Artery Disease (PAD): PAD is sometimes confused with DVT because both cause leg pain and discomfort. However, they affect completely different vessels — PAD affects arteries, while DVT affects veins. A vascular assessment correctly distinguishes between them.
Carotid Artery Disease: Like DVT, carotid artery disease is a condition involving blood vessel pathology that can lead to sudden, life-threatening events (stroke). Patients with generalised vascular risk factors — hypertension, diabetes, obesity, smoking — should be assessed for multiple vascular conditions.
If you have been diagnosed with any of these conditions, or if you have multiple vascular risk factors, a comprehensive vascular assessment with Dr. Ashutosh Kumar Pandey is strongly recommended.
DVT is not a condition to observe at home. It is not something that resolves with rest, warm water soaks, or pain balms. It is a vascular emergency that can progress to a fatal pulmonary embolism within hours — and the only way to prevent that outcome is prompt diagnosis and treatment by a specialist.
If you or a family member has:
— please do not delay. Seek immediate consultation with a vascular specialist.
Dr. Ashutosh Kumar Pandey is the best vascular surgeon in Lucknow for the diagnosis and treatment of Deep Vein Thrombosis, Pulmonary Embolism, and all related venous and arterial conditions. As the only MCh (Vascular Surgery) superspecialist trained at Sree Chitra Tirunal Institute, Trivandrum, practising in Lucknow, Dr. Pandey offers the complete range of treatment — from anticoagulation and catheter-directed thrombolysis to IVC filter placement and surgical thrombectomy — under one roof.
Disclaimer: This blog is intended for general educational and informational purposes only. It does not constitute medical advice, diagnosis, or a treatment recommendation. Always consult a qualified vascular surgeon for a personalised evaluation before making any medical decisions. Outcomes may vary from patient to patient.
