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Health condition

Pleural disease, when fluid, air or infection gathers around the lung.

The pleura is the lining of the lung, and it can be inflamed, filled with fluid, pus or air, or scarred. This overview explains how it is assessed and points you to the guide for each condition.

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A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Editorial team

    Written by our editorial team from the UK sources listed on each page.

  • 02

    Sourced from guidance

    Checked against British Thoracic Society (BTS) guidance and peer-reviewed sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK practice including ultrasound-guided sampling, indwelling pleural catheters and respiratory MDT review.

Key facts

Pleural disease at a glance.

The essentials, in plain English - what the pleura is, what can go wrong, and how it is investigated in the UK today.

  • What the pleura is

    A thin, two-layered membrane - one layer covering the lung, one lining the chest wall - with a film of fluid between them that lets the lung glide.

  • What can go wrong

    Inflammation (pleurisy), fluid (effusion), pus (empyema), air (pneumothorax), blood (haemothorax), plaques or thickening, and tumours including mesothelioma.

  • First tests

    A chest X-ray, then thoracic ultrasound - which confirms fluid and marks a safe site for any needle or drain.

  • Fluid analysis

    Samples are checked for protein and LDH (Light’s criteria), pH if infection is suspected, cell counts, culture and cytology.

  • Cause-specific care

    Treat the underlying problem, drain when needed, and use pleurodesis, an indwelling catheter or surgery when fluid or air keeps returning.

  • UK guidance

    Practice follows BTS pleural disease guidance, with complex cases discussed at a respiratory multidisciplinary team (MDT).

Why this guide matters

One space, many very different problems.

Chest pain and breathlessness can come from the pleura for many reasons. The three points below shape everything else on this page.

  • One symptom, many causes

    Sharp chest pain or breathlessness can come from fluid, air, infection or cancer - and the treatment for each is very different.

  • A sample beats a guess

    Ultrasound-guided aspiration and fluid analysis identify the cause in many patients, which is why a sample is usually sent rather than fluid simply drained.

  • Some causes are time-critical

    Tension pneumothorax, pleural infection and haemothorax need prompt hospital care - knowing the warning signs matters.

The pleural conditions

Find the guide for your condition.

Each has its own detailed guide. Where the cause is not yet known, the assessment below is how it is found.

Also see our guide to malignant mesothelioma, and pneumonitis, which inflames the lung tissue itself rather than its lining.

How the diagnosis is made

From first breathlessness to a clear cause.

The steps a UK respiratory team will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    History and examination

    Pain pattern, breathlessness, fever, cancer history, heart disease and - importantly - any asbestos exposure.

  2. 02

    Assessing

    Chest X-ray

    Usually the first image - shows fluid, air or a collapsed lung, though small collections can be missed.

  3. 03

    Assessing

    Blood tests

    Inflammatory markers and clotting, plus serum protein and LDH taken at the same time as any fluid sample.

  4. 04

    Sampling

    Thoracic ultrasound

    Confirms fluid, shows septations and marks a safe site. BTS advises ultrasound guidance for pleural fluid procedures.

  5. 05

    Sampling

    Aspiration and fluid analysis

    Appearance, protein and LDH (Light’s criteria), pH when infection is suspected, cell counts, culture and cytology.

  6. 06

    Deciding

    CT of the chest

    Often with contrast - shows pleural thickening, nodules, underlying lung disease and helps plan next steps.

  7. 07

    Deciding

    Thoracoscopy, biopsy and MDT

    If the cause is still unclear or cancer is suspected, pleural biopsy - then a respiratory MDT agrees the plan.

Typical timeline: urgent cases can be scanned and sampled within days - complex cases take longer while results and MDT discussion are awaited.

Symptoms

What pleural disease actually feels like.

Symptoms overlap between conditions, and some people have none. And the features that mean you should be seen quickly.

  • Pleuritic chest pain

    Sharp, stabbing pain worse on a deep breath or cough - the classic sign of an inflamed pleura.

  • Breathlessness

    Fluid or air stops the lung expanding fully - from mild on exertion to distressing at rest.

  • Dry cough

    A persistent, non-productive cough is common with pleural fluid or irritation.

  • Fever and sweats

    Suggest infection such as pneumonia with a parapneumonic effusion or empyema.

  • Heaviness or tightness

    A dull ache or sense of pressure on one side of the chest, often with a large effusion.

  • Shoulder-tip pain

    Irritation of the pleura near the diaphragm can refer pain to the shoulder.

  • No symptoms at all

    Pleural plaques and small effusions are often found by chance on a scan or X-ray.

  • Red flag - sudden pain with breathlessness

    Sudden onset suggests a pneumothorax or clot and needs same-day emergency assessment.

Treatment

How pleural disease is treated in the UK.

Management follows the cause - treat the underlying condition, drain what is needed, and step up to pleurodesis, catheters or surgery when problems recur.

  • Treat the underlying cause

    Heart failure, pneumonia, liver or kidney disease and cancer each have their own treatment - often the effusion improves as the cause is controlled.

  • Therapeutic aspiration

    A needle draws off fluid or air under local anaesthetic, guided by ultrasound - relieves breathlessness and is often used first.

  • Chest drain

    A small tube placed between the ribs, ideally under ultrasound guidance, drains fluid, pus, blood or air over hours to days.

  • Antibiotics and fibrinolytics

    Pleural infection needs prolonged antibiotics and drainage - intrapleural alteplase with DNase may be added for complex collections.

  • Pleurodesis

    Sterile talc is introduced to stick the two layers together, preventing fluid or air from returning - used for malignant effusion and recurrent pneumothorax.

  • Indwelling pleural catheter

    A thin tube left in place lets fluid be drained at home - a well-established option for recurrent malignant effusion.

  • Surgery (VATS)

    Keyhole surgery clears infected collections, treats recurrent or persistent pneumothorax and can free a lung trapped by scar tissue.

  • Oncology-led care

    For mesothelioma and pleural metastases, treatment is planned by the MDT - systemic therapy, symptom control and palliative support.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP or respiratory physician knows your history and can tell you which parts apply to you. If in doubt, get seen.

  • British Thoracic Society. Pleural Disease Guideline 2023 (Thorax 2023;78 Suppl 3).

  • British Thoracic Society. Pleural procedures and thoracic ultrasound guideline (2010).

  • British Thoracic Society. Spontaneous pneumothorax guideline (2010).

  • Light RW et al. Pleural effusions: the diagnostic separation of transudates and exudates. Annals of Internal Medicine, 1972.

Red flags

When chest symptoms need urgent attention.

Some pleural problems can be managed calmly in clinic. These cannot - seek same-day help, or call 999 for severe symptoms.

  • Sudden breathlessness with chest pain

    Suggests a pneumothorax - go to A&E or call 999, especially if severe or worsening.

  • Fever with pleuritic pain

    May mean pleural infection - a same-day assessment, because delays make empyema harder to treat.

  • Coughing up blood

    Haemoptysis needs prompt assessment for infection, clot or cancer - do not wait for it to settle.

  • Asbestos history with new symptoms

    New pleural fluid, pain or breathlessness after asbestos exposure warrants an urgent respiratory referral to exclude mesothelioma.

  • Collapse or severe distress

    Fast heart rate, blue lips, low blood pressure or collapse can indicate tension pneumothorax - call 999.

  • Pain with leg swelling or recent travel

    Pleuritic pain can be caused by a pulmonary embolism - especially after surgery, immobility or long-haul travel.

  • Chest injury then breathlessness

    Air or blood in the pleural space after trauma needs emergency assessment.

  • Unexplained weight loss or night sweats

    With a pleural effusion these features raise concern for cancer or chronic infection and need investigation.

  • Drain or catheter problems

    Fever, spreading redness, leakage or a drain that falls out - contact your pleural team the same day.

Living with it

Recovery, recurrence and staying well.

Four things that make the biggest difference after treatment - watching for recurrence, stopping smoking, planning travel sensibly and using the support on offer.

A quiet reminder

Early reporting makes treatment simpler.

A quick call about a new symptom is far easier for everyone than waiting until breathing is difficult.

  1. 01 Follow-up

    Know the signs of recurrence

    Returning breathlessness or one-sided chest tightness can mean fluid or air has come back - report it early rather than waiting for the next appointment.

  2. 02 Smoking

    Stopping smoking lowers your risk

    Smoking is a major risk factor for spontaneous pneumothorax and for lung disease that affects the pleura - stopping helps and support is available.

  3. 03 Travel

    Ask before you fly or dive

    After a pneumothorax, air travel and any diving need specialist advice - never assume it is safe once you feel better.

  4. 04 Support

    Ask about practical and emotional help

    For catheter care, asbestos-related disease or cancer, specialist nurses and palliative care teams can help with symptoms, benefits and wellbeing.

Frequently asked

Everything we get asked about pleural disease.

Quick answers on the pleura, fluid testing, asbestos plaques and when surgery is needed.

  • What is the pleura and what does it do?

    The pleura is a thin, two-layered membrane around each lung. One layer covers the lung and the other lines the inside of the chest wall. A small amount of lubricating fluid between them lets the lung slide smoothly as you breathe.

  • What is the difference between pleurisy, effusion, empyema and pneumothorax?

    Pleurisy is inflammation of the pleura, causing sharp pain on breathing. Pleural effusion is fluid in the space, empyema is infected fluid or pus, and pneumothorax is air, which can collapse the lung. They can overlap, and each has its own guide on this site.

  • How is fluid around the lung tested?

    After a chest X-ray, an ultrasound confirms the fluid and marks a safe site. A small needle then takes a sample, which is checked for protein, LDH, pH if infection is suspected, cells and cytology. Light’s criteria help separate transudates from exudates, alongside clinical judgement.

  • Does a pleural effusion always mean cancer?

    No. Heart failure, pneumonia and liver or kidney disease are common causes, and cancer is only one possibility. Because cancer is an important cause, a new unexplained effusion is normally sampled rather than assumed to be benign.

  • Are asbestos pleural plaques dangerous?

    Pleural plaques are usually harmless and are not cancer, and they do not turn into mesothelioma. They do show that you were exposed to asbestos, so report any new breathlessness, chest pain or weight loss to your GP promptly.

  • When is surgery needed for pleural disease?

    Surgery, usually keyhole (VATS), is considered when infection does not clear with drainage and antibiotics, when a pneumothorax keeps returning or does not seal, or when scar tissue traps the lung. Most pleural problems are managed without an operation.

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