Normal airways produce mucous. The mucous lines the airway’s surface to trap air borne particles, viruses, bacteria, and fungi. This trapped material, within a small amount of mucous, will be transported up the airways by the cilia, to be swallowed. The mucous also keeps the airways hydrated.
Diseases of the lungs produce abnormal looking mucous which is called sputum or phlegm.
Describing accurately your sputum will help your doctor come to an accurate diagnosis of your lung condition.
It is a good practice to take a photo of the sputum which you have coughed out to show to your doctor. A picture of the sputum is worth a thousand words.
Note the volume of the sputum. It can be a little, or copious, like half a cupful. Some patients with extensive bronchiectasis produce a large volume of sputum every day.
Note the viscosity of the sputum. Sputum which is fluid or watery can be coughed out easily. Sputum which is viscid or thick can be difficult to cough out. A bout of severe cough can worsen breathlessness and may cause a person to faint. Mucolytics can be taken orally to reduce the viscosity of the sputum making it more fluid to be coughed out.
Next note the colour of the sputum.
Healthy airways produce mucous which is fluid and clear.
Whitish sputum is somewhat thicker and cloudier. A viral infection may cause the sputum to be white in colour.
Yellow coloured sputum contains white blood cells, particularly neutrophils and eosinophils. These cells are present at the site of inflammation, like in asthma, or in bacterial infection.
Green coloured sputum has a higher concentration of white blood cells which are involved in fighting an infection caused by bacteria.
During an active infection, there is activation of the host defence mechanism which results in neutrophil recruitment in the airways, to kill the bacteria. This neutrophil influx is associated with a change in nature of the airway secretions from mucoid to purulent looking.
The release of myeloperoxidase from the neutrophils, during the killing of the bacteria, is what makes the sputum green. When the bacterial load is reduced or eliminated with antibiotic therapy, there is resolution of the secondary host defence response, and the colour of the sputum will return back to normal or white in colour.
Red coloured sputum denotes the presence of blood. During active airway bleeding, the colour of the sputum freshly coughed out is bright red. When the airway bleeding has stopped, the sputum will contain stale blood which is dark red in colour.
Sputum with brown and black specs within, commonly come from smokers or mine workers.
It is very important for patients with chronic lung diseases to note their usual sputum colour, which may not be normal, even when their diseases are in a stable condition. Things to note are cough frequency, sputum characteristics, level of breathlessness during daily activities and other constitutional symptoms like fever, fatique, tiredness, appetite and sleep.
During an acute exacerbation of COPD, following a viral or bacterial infection, a patient will experience more cough, increasing sputum volume with change in sputum colour and increasing shortness of breath, perhaps with wheezing. Noticing these worsening symptoms, the patient should seek medical advice immediately.
Your doctor may ask for your sputum to be collected. At times, three consecutive specimens, on different days, maybe required.
The best time to collect your sputum is in the morning. Gargle and rinse your mouth with water before collecting the specimen. This helps to eliminate prior, accumulated cells and bacteria in your mouth that may interfere with test results.
You may wish to perform the huff manoeuvre to bring phlegm up to the upper airways to be coughed out and collected.
The sputum specimen, about 5 ml or more, must be put into a sterile container which are available from clinics or laboratories.
Please remember to collect sputum and not spittle, which contains mainly saliva.
The specimen is best sent to the lab within 2 hours of collection.