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Sputum is the mucus you cough up from your lungs — not saliva or spit from the mouth. Looking at how much there is, its colour and how thick it is (and sometimes sending a sample to the laboratory) helps show whether there is a chest infection, how active a lung condition is, and whether airway-clearance treatment is doing its job.
What it tells us
Assessment of sputum — its volume, colour and consistency, and where indicated its microbiology and cytology — is a simple bedside outcome that reflects airway inflammation, infection and the effectiveness of airway clearance.1
How a sample is taken
The patient provides a deep-cough specimen (not saliva) into a clean pot, ideally first in the morning. Airway-clearance techniques or nebulised saline can help produce a sample. Twenty-four-hour volume, colour (against a validated colour chart) and viscosity are documented; when infection is suspected the sample is sent for microscopy, culture and sensitivity. A good-quality specimen contains few squamous (mouth) cells.
Sputum colour chart
Sputum colour is read alongside how much there is, how thick it is, and how it compares with your usual baseline — a sustained change matters far more than a one-off. An increase in volume together with a change in colour (usually toward deeper yellow or green) is a hallmark of a chest infection or exacerbation and may need a cardiorespiratory physiotherapy review — to step up your airway clearance and help decide whether antibiotics are needed. Any fresh blood should prompt review, and a large amount is an emergency. Validated colour charts predict bacterial load reasonably well, particularly in bronchiectasis and COPD.2,3
Use in cardiorespiratory physiotherapy
- Quantifying wet-sputum weight before and after treatment measures the effectiveness of airway clearance.
- Tracking colour and volume helps detect exacerbations early and prompt timely referral for antibiotics.
Cautions
Sputum must be distinguished from saliva and post-nasal secretions, or results mislead. Fresh blood (haemoptysis) should be escalated. Samples are handled with appropriate infection-control precautions, and sputum findings are always interpreted alongside the wider clinical picture.
References & evidence base
- Stockley RA, O’Brien C, Pye A, Hill SL. Relationship of sputum colour to nature and outpatient management of acute exacerbations of COPD. Chest 2000;117(6):1638–1645.
- Murray MP, Pentland JL, Turnbull K, MacQuarrie S, Hill AT. Sputum colour: a useful clinical tool in non-cystic fibrosis bronchiectasis. Eur Respir J 2009;34(2):361–364.
- Miravitlles M, Kruesmann F, Haverstock D, et al. Sputum colour and bacteria in chronic bronchitis exacerbations: a pooled analysis. Eur Respir J 2012;39(6):1354–1360.
References are numbered in citation order (Vancouver/BMJ style) and were current at the time of writing. Guidelines are living documents — verify against the latest version before clinical use.
Clearing mucus well is a skill rather than a machine. We match a technique to your lungs and your routine, then coach it until you can do it at home on a bad morning.
Corrections: If something on this page is wrong, out of date or unclear, we want to know. Email reception@inspireclinic.au with the page name and what you believe is incorrect. Substantive corrections are made promptly, and the guide’s version and last-updated date are changed to reflect it.