Brief overview
- What is sputum? Secretion from the airways when coughing
- What does sputum look like? e.g. white or colorless and clear (e.g. in COPD, asthma, cystic fibrosis), yellow-greenish and cloudy (e.g. in purulent angina, scarlet fever, pneumonia), brownish to black (e.g. in smokers) or bloody (e.g. in lung cancer).
- Cause: Natural cleansing process of the lungs to remove harmful substances and pathogens from the lungs.
- When to see a doctor? In the event of prolonged sputum production, blood contamination, additional symptoms such as fever or shortness of breath.
- Examination: Sputum examination in the laboratory
- Treatment: Depending on the underlying cause: e.g. mucolytic medication, antibiotics, inhalations.
Definition of sputum
Sputum is the medical term for sputum. It is a secretion or fluid produced by the mucous membrane of the bronchial tubes. It serves to cleanse the lungs. However, excessive sputum production can also be a sign of a respiratory disease.
Depending on the cause, the amount, color and consistency of the sputum may change. The appearance and consistency of the sputum often gives the doctor an initial indication of whether a respiratory disease (e.g. pneumonia, COPD, lung cancer, bronchitis) is present.
What does sputum look like?
The consistency of the sputum can also vary and can be thin, viscous, sticky, lumpy, crumbly, foamy or flaky, for example.
Meaning: Color and texture
Healthy sputum is usually glassy-bright and occurs only occasionally and in small quantities. Excessive or discolored sputum, on the other hand, often indicates a disease of the respiratory tract. On the one hand, inhaled pollutants (e.g. smoking) can damage the mucous membrane of the bronchial tubes, on the other hand, inhaled viruses, bacteria or fungi can trigger an infection and inflame the airways (respiratory tract infection). The color and consistency of the sputum provide an initial indication of the cause.
Important: Although the sputum can give the doctor an initial indication of the cause, further examinations are necessary for a reliable diagnosis.
Vitreous-whitish sputum
Increased, glassy-white sputum often indicates a viral infection such as acute bronchitis, flu or a simple cold.
However, chronic lung diseases such as COPD, bronchial asthma or chronic bronchitis as well as cystic fibrosis (cystic pulmonary fibrosis) can also lead to excessive production of glassy white sputum. The sputum is then usually thick and slimy. The sputum occurs over a longer period of time or repeatedly.
Yellowish-greenish sputum
Yellowish to greenish sputum usually contains pus and often indicates a bacterial respiratory infection such as purulent angina, scarlet fever, pneumonia, whooping cough or tuberculosis. In the case of bacterial infections, the sputum often also smells foul and is crumbly. Viruses are also rarely the cause of yellowish-greenish sputum.
If the mucus is yellow or green, this does not necessarily mean that bacteria are responsible for the infection. The doctor should therefore only administer antibiotics after a reliable diagnosis of a bacterial infection (in the laboratory).
Many of these illnesses are also accompanied by fever, cough and sore throat. However, a cough without sputum (e.g. dry cough) can also occur. It is also possible for sputum to be produced without a cough.
Large quantities of greenish-yellowish sputum may indicate pathological enlargement of the lungs (bronchiectasis). This sputum usually consists of a foamy upper layer, a mucous middle layer and a viscous sediment with pus (“three-layer sputum”). An allergy (allergic asthma) can also be the cause of yellowish sputum.
Greyish, brownish or black sputum
Smoker’s cough, on the other hand, usually occurs together with brown or, more rarely, black sputum in the morning.
Bloody sputum
Sputum that contains blood (hemoptysis) may look pink, light red or rusty brown and contain red or brown spots. It may indicate an injury or disease of the respiratory tract. For example, rusty-brown secretions sometimes occur in pneumonia.
Bright red and streaky bleeding in the sputum is also frequently seen in the case of an inflamed trachea or bronchial tubes as well as lung cancer. However, aspergillosis (a disease caused by molds), COPD, chronic bronchitis, bronchial asthma, lung abscesses, bronchiectasis or tuberculosis can also lead to blood in the sputum. In the case of tuberculosis in particular, this usually manifests itself in the form of small blood spots in the sputum.
If the sputum consists exclusively of blood (hemaptoe), this can also indicate lung cancer or a burst bronchial artery. Pink and frothy sputum, on the other hand, usually indicates pulmonary edema. This is water in the lungs, which is a medical emergency.
How is sputum produced?
The bronchial system is embedded in the lungs and functions like a tube system that transports oxygen into the body. From the lung tube, the bronchi branch out into both lungs like the branches of a tree. In the mucous membrane of the bronchi, certain cells – so-called goblet cells – form a secretion that covers a large part of the airways with a thin layer of mucus.
This has the task of protecting the lungs from foreign bodies, dust, pathogens (e.g. viruses, fungi, bacteria) or smoke particles. To do this, the cilia on the surface of the mucous membrane transport the secretions to which the harmful substances adhere towards the mouth in rhythmic movements, as if on a treadmill. There it is then coughed up in the form of sputum (productive cough). The formation of sputum is therefore a natural reaction of the body to cleanse the airways.
However, if the mucous membrane is damaged (e.g. by smoking), viruses, bacteria and other harmful organisms can easily multiply on it and cause inflammation, for example. As a result, the mucus-producing cells produce more and more (usually thickened) mucus to cleanse the lungs of harmful substances. Depending on the cause, the color and consistency of the sputum may also vary (see above).
When to see a doctor?
- the sputum and cough persist for more than a few days.
- the sputum is bloody or purulent (yellowish) in color.
- additional symptoms such as fever, chest pain or shortness of breath occur.
Bloody sputum must be checked by a doctor, especially in smokers.
How does the doctor examine sputum?
The color and consistency of the sputum can give the doctor an initial indication of the cause and possible illnesses. However, in order to make a reliable diagnosis, the doctor will usually carry out further examinations. For example, the doctor will examine the sputum in the laboratory under a microscope (sputum examination).
This allows pathogens such as bacteria, fungi or viruses, which are often responsible for respiratory infections, to be detected in the sputum. The doctor can also detect pathologically altered cells in the sputum, which can sometimes indicate lung cancer.
If necessary, the doctor will also carry out a blood test to determine the inflammation levels and possible pathogens. Depending on the suspected cause, the doctor will then arrange further examinations such as a lung X-ray, CT scan, MRI or bronchoscopy.
How is the sputum examination carried out?
If an infection with bacteria or fungi is suspected, the sputum sample is stored in a nutrient solution in an incubator for a few days. If a bacterial or fungal culture grows from it, the doctor can then determine the exact pathogen and initiate the appropriate treatment.
The following tips will help you to obtain sputum:
- It is easiest to cough up sputum in the morning after getting up.
- Rinse your mouth thoroughly with tap water beforehand. This ensures that the sputum mixes as little as possible with the germs naturally present in the mouth (oral flora). Important: Do not brush your teeth beforehand and do not rinse your mouth with mouthwash.
- Cough the mucus forcefully upwards into your mouth and then spit it into the cup. To obtain a sufficient amount, it is often necessary to repeat the process.
- Close the cup immediately afterwards and hand it in to the doctor as soon as possible. If this is not possible, keep the container with the sputum in the refrigerator until you hand it in.
What does the treatment look like?
In the case of respiratory tract infections accompanied by coughing and sputum production, it is important that you drink enough and take it easy physically. In the case of a productive cough, the doctor may also prescribe expectorant medication in the form of tablets, juices or inhalations. These agents make the viscous mucus more fluid and make it easier to cough up the sputum. Anti-inflammatory medication can also help with inflammation of the bronchial tubes. It is best to ask your doctor or pharmacist about this.
