Pulmonary embolism: symptoms, causes, tests and treatment

The NHS lists the main symptoms as difficulty breathing that comes on suddenly, chest pain that is worse when you breathe in, and coughing up blood. You may also have pain, redness and swelling in one leg, usually the calf, which are symptoms of a blood clot (DVT).

Patient.info says symptoms depend on how large the clot is and how well your lungs can cope, and that they often start suddenly. A small PE may cause no symptoms at all, mild to obvious breathlessness, sharp pain on breathing in, coughing up blood, a mildly raised temperature or a fast heart rate. A massive PE or many clots may cause severe breathlessness, chest pain behind the breastbone, feeling faint or unwell, or collapse.

The NHS says to call 999 or go to A&E if any of these apply, because they could be signs of a pulmonary embolism or another serious condition. Do not drive to A&E: ask someone to drive you or call 999 for an ambulance, and bring any medicines you take.

• You have severe difficulty breathing.

• You feel pain in your chest or upper back.

• Your heart is beating very fast.

• Someone has passed out.

• The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you have difficulty breathing that comes on suddenly, or you are coughing up blood.

A pulmonary embolism (PE) is a blockage in one of the arteries in the lungs, usually caused by a blood clot. Patient.info says PE is part of a group of problems known as venous thromboembolism (VTE), alongside deep vein thrombosis (DVT).

In a typical case, a clot forms in a deep vein, usually in the leg or pelvis, breaks off and travels through the circulation until it lodges in a narrower blood vessel in the lung. NICE CKS describes PE as a life-threatening condition in which the clot obstructs the pulmonary arterial system and causes severe respiratory dysfunction.

Patient.info says that in almost all cases the cause is a blood clot that originally formed in a deep vein (a DVT). Rarely, the blockage may be something other than a clot, such as fatty material from a broken thigh bone, an air bubble or amniotic fluid in pregnancy.

NICE CKS lists major risk factors, and the NHS and Patient.info add to them.

• DVT, or a previous DVT or PE.

• Recent surgery, particularly pelvic, leg or gynaecological operations, and significant immobility.

• Active cancer, and blood conditions that make clots more likely (thrombophilia or antiphospholipid syndrome).

• Lower limb trauma, a recent heart attack, increasing age or a family history of DVT.

• Pregnancy and in particular the 6 weeks after giving birth.

• NICE CKS also lists combined oral contraception, hormone replacement therapy, smoking, long-duration travel and obesity.

• Patient.info says half of all people with a PE develop it when they are hospital inpatients. The NHS says risk of a travel-related DVT increases for flights lasting more than 4 hours.

Patient.info says diagnosis is often suspected from symptoms and history, for example sudden breathlessness after major surgery and immobility. Doctors may use the Wells score, which weighs signs of DVT, heart rate, recent immobility or surgery, previous DVT or PE, coughing up blood, cancer treatment and whether another diagnosis is less likely.

NICE CKS describes using the two-level Wells score to decide next steps: if PE is likely, an immediate CTPA scan is arranged (with interim anticoagulation if there is a delay), and if PE is unlikely, a D-dimer test is arranged. It says immediate hospital admission should be arranged for anyone who is pregnant or has given birth within the past 6 weeks.

The NHS says that if a GP thinks you have a PE you will be sent to hospital for tests and treatment, and you will probably be given an injection of anticoagulant medicine before any test results. Anticoagulants stop blood clots getting bigger and prevent new clots forming.

If tests confirm PE, the NHS says you continue with anticoagulant injections for at least 5 days and take anticoagulant tablets for at least 3 months. Patient.info says anticoagulation alters chemicals in the blood so clots form less easily, and does not dissolve the clot, which the body then breaks up itself. Apixaban or rivaroxaban tablets are offered to most people with confirmed PE, and treatment usually continues until 3 months after the PE, sometimes longer if there is a high risk of another.

Patient.info says oxygen is given in the early stages, and that people with features of a large PE, such as low blood pressure, fast heart rate or low oxygen levels, need to be admitted. Clot-dissolving medicine (thrombolysis), filters in a large vein or surgery are used for high-risk cases or when anticoagulants cannot be given.

NICE CKS lists pregnancy, and in particular the 6 weeks postpartum, as a major risk factor, and says anyone who is pregnant or has given birth within the past 6 weeks with suspected PE should be admitted to hospital immediately.

Patient.info says a pregnant woman with symptoms or signs suggesting PE should be admitted quickly because PE in pregnancy is very serious and rapid diagnosis and treatment are essential. It says leg compression ultrasound may be useful when radiation from other imaging may be harmful.

It also says that if you are pregnant, regular heparin injections are used rather than warfarin tablets because warfarin can potentially harm the unborn baby, and the newer anticoagulants are not suitable in pregnancy.

The NHS says that if you are being treated in hospital for another condition, your medical team should take steps to prevent DVT. For long journeys it advises:

• Sit comfortably, choose an aisle seat if possible, wear loose-fitting clothing and make sure you have plenty of leg room.

• Drink water regularly and take regular breaks from sitting.

• Bend and straighten your legs, feet and toes every 30 minutes while seated, and press the balls of your feet down against the floor.

• Wear flight socks.

• Do not sit for long periods without moving, drink alcohol or too much caffeine, or take sleeping pills.

The NHS says you should make a full recovery if the PE is spotted and treated early. NICE CKS says that left untreated the prognosis is poor and the risk of death is high, and that some people develop complications after treatment such as chronic thromboembolic pulmonary hypertension.

After hospital, NICE CKS says primary care follow-up should include monitoring of treatment, an anticoagulant information booklet and alert card, and for an unprovoked PE, investigations to assess for undiagnosed cancer and, where appropriate, hereditary thrombophilia testing.

Suspected pulmonary embolism is an emergency. Assessment is through 999, emergency departments or acute medical units, where scans and treatment are started without waiting for a routine appointment. A private appointment is not a substitute for emergency care if you have sudden breathlessness or chest pain.

After discharge, your GP or a specialist clinic usually manages how long to continue anticoagulants and whether any underlying cause needs investigation. Some people choose a private haematology or respiratory review afterwards, which should complement rather than replace the NHS follow-up.