Sputum : Causes, Symptoms, Diagnosis & Treatment

Last Updated: 21/08/2022

Sputum is the pathological contents of the respiratory tube, represented by the discharge of glandular cells of the mucous membrane of the trachea and bronchi with an admixture of saliva, nasopharyngeal secretion. Coughing up of sputum occurs during infectious and inflammatory processes of the upper and lower respiratory tract, allergies, inhalation of irritating substances. Radiation studies of the chest, bronchoscopy, and laboratory tests help to identify diseases in which sputum appears, to establish the causes of the formation of pathological mucus. The choice of treatment tactics depends on the nature of the underlying pathology.

general characteristics

In the lumen of the tracheobronchial tree of a healthy person, up to 10 ml of transparent mucus is collected during the day, which has bactericidal properties, is involved in metabolism, elimination of infectious agents and small foreign particles from the respiratory tract. Secretion formation does not cause coughing or discomfort and goes unnoticed. Sputum is secreted in excess in diseases of the nose, its paranasal sinuses, respiratory and digestive organs.

The volume of discharge varies depending on the pathological process, in some diseases it reaches 400 ml per day. Sputum can be easily separated or coughed up with difficulty. Mucus often contains blood impurities, foreign inclusions (dust, metal particles, microliths). In most cases, the bronchial secret is odorless, the nature of the underlying disease affects the color.


The consistency of sputum is thick, viscous and liquid watery. When settling, it in some cases is divided into 2 or 3 layers. According to physical properties (color, smell, transparency, other macroscopic characteristics), the following types of sputum are distinguished:

  • Serous. It is isolated in acute left ventricular failure, accompanied by pulmonary edema. Characterized by the absence of smell, watery consistency, an abundance of foam. Serous sputum is usually colorless, sometimes with a pinkish tint.
  • Mucous. The appearance of a mucous discharge indicates the onset of inflammation of the respiratory tract or the attenuation of the activity of an acute pathological process. Sputum is coughed up in a small amount, it is a colorless viscous mucus.
  • Mucopurulent. It is formed in the acute period of many diseases of the respiratory system. For such a secret, an increased viscosity is typical, the presence of impurities of yellow or green color.
  • Purulent. Appears with severe inflammation, suppurative processes of the respiratory system. The consistency of the purulent secret is liquid, the color is green or yellow-green, sometimes there is a putrid smell.

Perhaps hidden here are shocking photos of medical operations that show blood and intestines Are you 18 years old? yes no Purulent sputum


Reasons for the formation of sputum

Causes of purulent sputum

The appearance of purulent yellow or yellow-green discharge indicates the presence of a severe acute respiratory infection or an exacerbation of a chronic inflammatory disease of the respiratory tract. Purulent fetid sputum secreted with a cough accompanies various destructive processes of the lungs, it is observed with stagnation of pathological contents in bronchiectasis. The most common causes of purulent secretion are:

  • Bronchitis: acute purulent bronchitis, chronic purulent process in the acute phase.
  • Bronchiectasis: bronchitis or mixed variant of COPD, bronchiectasis.
  • Pulmonary destruction: lung gangrene, lung abscess.
  • Neoplasms: decaying lung cancer.

Causes of thick/viscous sputum

Coughing up of viscous mucus or mucopurulent secretion occurs in most diseases of the bronchopulmonary system. Any acute respiratory pathology manifests as an unproductive cough with thick light or yellowish sputum. Chronic diseases are accompanied by the release of a viscous secret during remission. The most common coughing up of thick mucus is observed in the following pathologies:

  • Acute respiratory infections: tracheitis, bronchitis, pneumonia.
  • Hereditary diseases: cystic fibrosis, Kartagener's syndrome.
  • Pulmonary mycoses: candidiasis, aspergillosis, zygomycosis.
  • Chronic lung diseases: COPD, bronchial asthma, chronic bronchitis.

Causes of mucous sputum

Some diseases of the respiratory system are manifested by the discharge of liquid watery mucus. Sometimes such sputum is secreted by single spitting, but in a number of diseases there is a lot of it. Cough with mucus is often observed in acute infections of the airways. Mucous sputum, the causes of which are associated with chronic pathology, is coughed up during remission. Excessive production of clear mucus occurs against the background of the following conditions:

  • Manifestation of acute respiratory diseases: bronchitis, pneumonia.
  • Remission of chronic respiratory pathology: COPD, chronic bronchitis.
  • The onset of bronchial asthma.
  • Infiltrative pulmonary tuberculosis.
  • Neoplastic process:  non-small cell carcinoma, lung adenomatosis.
  • Diseases of the digestive system: GERD.

Causes of yellow sputum

Often the sputum secreted by the patient turns yellow due to the activation of the bacterial microflora. The appearance of such mucus in the morning may occur due to the admixture of nasal secretion, which flows into the trachea during sleep. Sometimes sputum acquires a rich yellow tint due to food coloring, an increased content of eosinophils. The main diseases with the release of yellow sputum:

  • Diseases of the nose, paranasal sinuses: rhinitis, sinusitis.
  • Acute diseases of the respiratory system: bronchitis, tracheitis, pneumonia.
  • Chronic respiratory diseases: chronic bronchitis, bronchiectasis, COPD.
  • Eosinophilic infiltrates: ascariasis, hookworm, drug allergy.
  • Specific infections: pulmonary forms of syphilis, tuberculosis.

Causes of mucopurulent sputum

Expectoration of mucus with pus indicates an acute advanced stage of bronchopulmonary disease. Sometimes mucopurulent sputum is rusty in color and may contain streaks or droplets of blood. Simultaneously with the appearance of pathological impurities, the volume of the discharge increases. The main diseases in which there is a release with a cough of mucopurulent contents:

  • Acute diseases of the bronchi, lungs: bronchitis, pneumonia.
  • Chronic pathology of the respiratory tract: chronic bronchitis, COPD, the presence of bronchiectasis.
  • Specific diseases: tuberculosis of the bronchi, lungs, pulmonary syphilis.
  • Rare hereditary pathology: cystic fibrosis.
  • Malignant neoplasms: bronchopulmonary carcinoma.
  • Pulmonary mycoses: actinomycosis.

Causes of fetid sputum

A strong unpleasant odor of sputum is due to stagnation of the contents of the cavity formations of the lungs, putrefactive processes associated with the activity of anaerobic microflora. When such a cavity is drained into the bronchus, a fetid semi-liquid secret is coughed up in large quantities. Morning sputum sometimes smells strongly due to impurities from the discharge of the nasopharynx. The main pathologies accompanied by this symptom include:

  • Suppurative pulmonary diseases: lung abscess, lung gangrene, pleural empyema.
  • Neoplastic processes: the disintegration of a cancerous tumor.
  • Specific infections: decay of syphilitic gum, drainage of a tuberculous cavity.
  • bronchiectasis.
  • Diseases of the nasopharynx: Ozena.

Causes of green sputum

Green sputum is the result of bacterial infection and stagnation of secretions in the respiratory tube, bronchiectasis, and cavity formations. Such discharge usually has a purulent, mucopurulent character, sometimes has an intense putrefactive odor. Coughing up green contents may indicate a serious bronchopulmonary disease, often observed in pathologies such as:

  • Acute diseases of the respiratory system: bronchitis, pneumonia.
  • Pulmonary purulent destruction: gangrene, lung abscess.
  • Suppurative diseases of the pleura: pyothorax.
  • Tuberculosis of the respiratory organs: fibrous-cavernous pulmonary tuberculosis, pleural empyema with tuberculous pleurisy.
  • Bronchiectasis of any origin.
  • Hereditary diseases: cystic fibrosis.


Diagnosis of diseases in which sputum is separated is carried out by pulmonologists or therapists. During the survey, the duration of the disease, the presence of occupational hazard, and the relationship with smoking are specified. Examination reveals signs of hypoxia, symptoms of distal hypertrophic osteoarthropathy. To finally find out why the patient coughs up sputum, the following methods help:

  • Physical research. Local dullness of percussion sound suggests pneumonia, the presence of pleural effusion. Dry wheezing during auscultation indicates bronchial obstruction, moist and crepitating pathological breath sounds are heard during infiltration of the lung tissue.
  • visualization methods. X-ray of the lungs reveals infiltrates of the pulmonary parenchyma, spherical formations, the presence of lung destruction. CT, MRI of the chest are prescribed to clarify the localization of the pathological process. Visualization of signs of pyothorax can be done using X-ray examination or ultrasound of the pleural cavity.
  • Endoscopic techniques. Bronchoscopy makes it possible to examine the mucous membrane of the bronchi, trachea. Using this method, you can detect manifestations of bronchitis, bronchiectasis, bronchoconstriction zones. Under the control of a bronchoscope, a biopsy of suspicious sections of the bronchial wall is performed. Fibrogastroscopy is performed to exclude GERD, rhinoscopy - if a pathology of the nasopharynx is suspected.
  • Laboratory research. Peripheral blood tests reflect inflammatory changes in the body. During a microscopic examination of sputum, its physical qualities are evaluated, Kurshman spirals, Dietrich plugs, and other inclusions are detected. The cultural method allows you to detect the causative agent of an infectious disease, to determine its sensitivity to antibiotics.

Sometimes, when coughing with sputum, spirometry, body plethysmography, and allergy diagnostics are additionally performed. To exclude syphilis, helminthic invasions, pulmonary mycoses, serological tests are performed. For the diagnosis of hereditary pathology, molecular genetic methods and special studies are used. To confirm tuberculosis, the Mantoux test, diaskin and quantiferon tests can be used.

Bronchoscopy is performed for both diagnostic and therapeutic purposes.



Help before diagnosis

Long-lasting, regularly expectorated sputum is a reason for a mandatory visit to the doctor. When coughing up liquid purulent contents with a full mouth, hemoptysis or rusty sputum, a visit to a medical facility should be urgent. Before establishing a diagnosis, it is recommended to drink plenty of warm alkaline drinks, expectorant herbal preparations and medicines, and breathing exercises.

Conservative therapy

There are a large number of pathologies in which sputum is coughed up, treatment depends on the etiology and mechanism of the development of the disease. Conservative measures include the use of pharmacological agents and physiotherapeutic procedures, physiotherapy exercises. Medicines can be divided into the following groups:

  • Etiotropic. Antibiotics are prescribed for a bacterial infection, taking into account the sensitivity of the microflora. In the treatment of tuberculosis, combinations of anti-tuberculosis drugs are used. Antifungal drugs are indicated for fungal diseases, anthelmintic drugs for helminthic invasions.
  • Pathogenetic. Includes expectorants. Against the background of treatment, sputum becomes more liquid, better excreted from the bronchi. Preference is given to mucolytics and mucoregulators. The group of pathogenetic agents also includes bronchodilators, corticosteroid hormones used in bronchial obstruction. Anticancer drugs are recommended for malignant neoplasms.

In a number of pulmonary diseases, physiotherapy is actively used. Patients are prescribed medicinal inhalations, breathing exercises. Sputum is well coughed up after percussion massage of the chest. Patients are trained in postural drainage techniques. If necessary, sanation bronchoscopy is performed.


Surgical treatment is subject to patients with abundantly secreted purulent sputum, which is formed during suppurative-destructive diseases, as well as patients with lung tumors. The volume of the operation depends on the prevalence and nature of the pathological process. Segmental resections, lob-, bilo- and pulmonectomy are carried out. With pyothorax, drainage of the pleural cavity is performed.

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