Blood clots & lung circulation - Adult patient guide
Blood Clots: DVT and Pulmonary Embolism Explained
An unexplained swollen leg or sudden breathlessness should not be dismissed as a muscle strain or lack of fitness. A blood clot in a deep vein can travel to the lungs, where prompt assessment and treatment can be lifesaving.
Deep vein thrombosis (DVT) is a clot in a deep vein, often in a leg. Pulmonary embolism (PE) is a blockage in a lung artery, usually caused by a clot traveling from elsewhere. Suspected PE needs urgent hospital assessment; treatment commonly involves anticoagulants.
New one-sided leg swelling needs prompt assessment. Sudden breathing difficulty may be an emergency.
The medicine and duration depend on the clot, its cause and your bleeding risk.
Persistent breathlessness after a PE deserves reassessment, even when treatment has been completed.
When to seek urgent help
New pain, swelling, warmth or discoloration affecting one leg can indicate DVT and needs prompt medical review. If leg symptoms occur with chest pain or breathlessness, treat this as an emergency. Other conditions can look similar, so symptoms alone cannot establish the diagnosis. [1], [2]
How DVT and pulmonary embolism are related
Doctors use the term venous thromboembolism (VTE) for DVT and PE together. Deep-vein clots often arise in the leg or pelvis; part of a clot may break away and pass through the right side of the heart into a lung artery. A PE can occur without obvious leg symptoms. [3]
A lung clot can interfere with blood flow and put strain on the right side of the heart. Its seriousness depends on its effects on circulation and breathing, as well as the person's underlying health. This is different from the artery blockage that usually causes a heart attack.
Why do blood clots develop?
Risk increases with recent surgery, hospitalization, reduced mobility, a previous clot, active cancer, pregnancy or the period after childbirth, and estrogen-containing contraception or hormone therapy. Some inherited or acquired clotting disorders also contribute. Several risks may be present together. [2], [3]
A clot after a temporary trigger is often described as provoked. Sometimes no clear trigger is found. Tell your clinician about recent travel, injuries, operations, family history and every medicine you take; this helps guide the assessment and longer-term plan.
Long journeys involving prolonged sitting can add to risk, especially when other factors are present. The issue is immobility: it can occur in a car, bus or train as well as on an aircraft. [6]
How are blood clots diagnosed?
| Test | What it contributes |
|---|---|
| Leg ultrasound | Looks for a clot in the deep veins when DVT is suspected. |
| D-dimer blood test | Can help exclude a clot in appropriately selected patients. A raised result alone does not prove DVT or PE. |
| CT pulmonary angiography (CTPA) | A contrast-enhanced CT examination of the lung arteries, commonly used to investigate PE. |
| Ventilation-perfusion (V/Q) scan | An alternative lung scan in selected circumstances, for example when CTPA is unsuitable. |
The sequence depends on clinical probability, pregnancy, kidney function, contrast reactions and other factors. A normal home oxygen reading or ordinary chest X-ray does not replace a proper assessment for suspected PE. [4], [5]
Further investigations for an underlying cause are selected from your history, examination and initial results. An unexplained clot does not automatically mean cancer, and extensive cancer scans or inherited clotting tests are not appropriate for everyone. [5]
What treatment involves
Anticoagulants reduce further clot formation and help prevent an existing clot from enlarging while the body gradually clears it. Options include injections and tablets such as apixaban, rivaroxaban or warfarin. They are not interchangeable: pregnancy, kidney function, cancer, antiphospholipid syndrome and other medicines may change the choice. [4]
A severely unwell person may need clot-dissolving treatment or a specialist procedure. These treatments carry risks and are reserved for selected situations. Hospital assessment is essential, but a carefully assessed low-risk PE may sometimes be managed through a structured outpatient pathway with reliable follow-up. [4], [5]
Confirmed PE or proximal DVT generally requires at least three months of anticoagulation. At review, the clinician balances recurrence and bleeding risks before deciding whether to stop or continue. Do not stop treatment simply because the pain or breathlessness has improved. [5]
Taking anticoagulants safely
Know your medicine's name, dose, schedule and missed-dose instructions. Tell doctors, dentists and pharmacists that you take an anticoagulant. Check before adding aspirin, anti-inflammatory painkillers or herbal products, and ask for a plan before procedures. Warfarin requires INR blood tests; other anticoagulants still require appropriate clinical monitoring.
[7]Recovery and breathlessness after a PE
Recovery varies. Discuss a gradual return to normal activity and seek advice before flying after a recent clot. New or worsening chest pain or breathing difficulty should be assessed urgently rather than assumed to be part of recovery. [1], [2]
Some people remain breathless despite anticoagulation. There are several possible causes; one is persistent obstruction in the lung arteries, which can lead to chronic thromboembolic pulmonary hypertension (CTEPH). Our pulmonary hypertension guide explains why this needs specialist assessment. Do not wait for a scheduled follow-up if symptoms deteriorate. [8]
Bring your hospital discharge summary, scan reports, anticoagulant details and a record of symptoms to follow-up. Routine lung-function testing does not diagnose an acute clot; it may answer other questions when persistent breathlessness is being investigated.
Reducing future risk
During hospital care, the team should assess both clotting and bleeding risk before choosing preventive medicines or mechanical measures. Preventive anticoagulants are not automatically suitable for every hospitalized patient. [9]
On long journeys, move your ankles and calves and walk periodically when safe. If you have a previous clot or other significant risk factors, discuss whether properly fitted compression stockings or medication are appropriate. Do not start aspirin or anticoagulants yourself for travel. [6]
After a clot, ask for a written plan covering future surgery, prolonged travel, pregnancy and any treatment changes. The aim is practical prevention without unnecessary medication.
Patient videos in English and Urdu
You can also watch the clinic's explanations of pulmonary embolism in English and Urdu. They complement an individual care plan; urgent symptoms require medical care.
Common questions
Can I have a pulmonary embolism without a swollen leg?
Yes. A PE can occur without noticeable DVT symptoms. Sudden unexplained breathlessness or chest pain still needs urgent assessment.
Does a high D-dimer mean I have a clot?
No. D-dimer can rise for several reasons. Clinicians interpret it with the probability of a clot and arrange imaging when indicated.
Will I need blood thinners for life?
Not necessarily. Some people need a defined course; others benefit from extended treatment. The decision depends on the cause, recurrence risk, bleeding risk and your preferences.
Can I walk after a DVT or PE?
Once assessed and treated, many people are encouraged to return gradually to activity. Follow your treating team's advice, particularly after a severe PE or if symptoms persist.
When should persistent breathlessness be reviewed?
Discuss it at follow-up, especially if recovery stalls. Sudden or worsening breathlessness, chest pain or fainting needs urgent assessment rather than a routine appointment.
Follow-up after a lung clot in Lahore
For non-emergency review after hospital treatment or persistent breathing symptoms, bring your records to Australian Polyclinic, DHA Phase 5. Suspected acute DVT or PE requires urgent assessment; a routine clinic appointment is not an emergency pathway.
Request a follow-up consultationCall 0311 057 3333General patient information; diagnosis and treatment depend on an individual assessment. Severe or rapidly worsening symptoms need urgent care.