SYMPTOMS

What is expectoration?

Sputum is the secretion from the trachea, bronchi, or exudate from the alveoli. The act of expelling sputum from the mouth through the force of airflow during coughing is called expectoration.

Normally, the respiratory tract secretes a small amount of viscous fluid to keep the mucous membrane moist. When the respiratory tract is infected by pathogens, irritated by foreign substances, or triggered by allergies, an inflammatory response occurs, leading to increased mucus secretion. This mucus mixes with immune reaction products, inhaled dust, and damaged tissues to form sputum.

Additionally, pulmonary congestion or edema can cause fluid exudation in the lungs and bronchi, resulting in expectoration. Abnormal increases in respiratory secretions may also be expelled through the mouth.

Sputum can be classified based on its nature^[1]:

• Mucoid sputum: Thick and sticky, often difficult to expel due to high viscosity. It is usually colorless, transparent, or slightly white and is commonly seen in respiratory inflammation, asthma, lobar pneumonia, etc.
• Serous sputum: Thin and watery, sometimes foamy, typically seen in pulmonary congestion or edema.
• Purulent sputum: Discolored, appearing yellow, green, or other opaque purulent fluids. It is usually caused by bacterial or viral infections in the respiratory tract, such as tuberculosis, lung abscess, or advanced cancer with secondary infection.
• Bloody sputum: Sputum containing blood streaks or clots.

TREATMENT

How to relieve phlegm?

• Back patting: It can cause vibrations in the air in the lungs, loosening and dislodging phlegm attached to small bronchi and moving it into larger bronchi.
• Effective coughing: Deep breathing can expand the lungs to their maximum capacity, and rhythmic deep breathing can induce coughing.
• Drinking water: Water moistens the respiratory tract and thins phlegm. Those with thick, difficult-to-expel phlegm should drink plenty of water.

It is important to note that if these measures do not alleviate phlegm or if symptoms worsen, seek medical attention promptly to further identify the cause.

DIAGNOSIS

Under what circumstances should you seek medical attention for phlegm?

• Persistent phlegm production lasting two weeks or longer, which may indicate chronic respiratory disease;
• Coughing up phlegm accompanied by other abnormal symptoms such as fever, chest pain, weight loss, or wheezing;
• Production of purulent or bloody phlegm;
• Abnormal phlegm color, such as yellow, bright green, rust-colored, or bloody phlegm, or changes in texture, such as sticky, stringy mucus;
• Daily production of large amounts of frothy, serous phlegm;
• Presence of foreign material in the phlegm, such as membrane-like substances.

POTENTIAL DISEASES

What are the possible causes of sputum production?

Both upper and lower respiratory tract diseases can cause sputum production^[2]:

• Mucoid sputum is commonly seen in acute tracheobronchitis, bronchial asthma, and the early stages of lobar pneumonia, as well as tuberculosis. Chronic cough with small amounts of mucoid sputum may indicate chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis with airflow limitation and/or emphysema.

• Thin, watery, pink, and frothy sputum is often associated with pulmonary edema.

• Purulent sputum occurs in bacterial infections of the lower respiratory tract; foul-smelling sputum suggests anaerobic bacterial infection. Yellow-green or emerald-green sputum may indicate Pseudomonas aeruginosa infection, while golden-yellow sputum is seen in Staphylococcus aureus infection. White, thick, and stringy sputum that is difficult to expectorate may suggest fungal infection.

• Dark red sputum resembling rust color is indicative of Streptococcus pneumoniae pneumonia.

• Bloody sputum results from damage to the respiratory mucosa, vascular rupture, or blood entering the lungs. It may occur in lung tumors, lung cancer, tuberculosis, bronchiectasis, or acute pulmonary edema.

• Watery sputum in large quantities with membrane-like fragments resembling eggshell may suggest hydatid disease (echinococcosis).

• Increased sputum volume is commonly seen in bronchiectasis, lung abscess, and bronchopleural fistula.

• If hundreds to thousands of milliliters of frothy serous sputum are produced daily, the possibility of lung adenocarcinoma should also be considered.