Sputum examination

Anamnesis collection and obtaining the material

Patient complaints of a productive cough require detailed clarification. It is important to remember that a strong cough effort does not always guarantee expectoration. The patient may not produce sputum due to its increased viscosity or may simply swallow the secretion (the latter is especially typical for women and children).

Often, patients omit mentioning the presence of secretions. For instance, scanty morning sputum in the "smoker's bronchitis" phenomenon is perceived by the patient as normal. The doctor's task is to actively identify this complaint during the interview.

Key questions for productive cough:

• Dynamics and volume: frequency of coughing and daily amount of secretion.
• Mechanics: how difficult it is to expectorate the sputum.
• Postural dependence: whether a drainage position exists (body position in which the secretion drains better).
• Characteristics: color, presence of solid particles, plugs, or blood (bright red or dark).

The material can be obtained through natural expectoration or instrumentally (aspiration during bronchoscopy). The main rule: the material must come from the trachea and bronchi without saliva contamination. This is critically important for subsequent microscopy and Gram staining.

Diagnostic value of volume and consistency

The amount of sputum produced varies in a very wide range. Abundant production, reaching 1–1.5 liters per day, is a formidable symptom and is characteristic of:

• Large bronchiectasis;
• Lung abscess and tuberculous cavities;
• Pulmonary edema (toxic or cardiogenic);
• Rupture of pleural empyema into the bronchus;
• Bronchorrhea.

The consistency of the secretion directly depends on the pathological process. In purulent-inflammatory diseases, the character of the sputum is mostly mucopurulent, and its thickness (liquid or viscous) is determined by the mucus content.

Particularly viscous sputum is typical for acute inflammatory processes and the initial period of a bronchial asthma attack. Conversely, a liquid or serous consistency is less common (e.g., in pulmonary edema).

Macroscopic evaluation: color and odor

Visual evaluation of sputum provides the physician with immediate clues about the nature of the disease.

What the color indicates:

• Yellowish-green: indicates the presence of pus and a bacterial infection.
• Yellow (canary): a sign of accumulation of a large number of eosinophils (typical for bronchial asthma and allergic processes). Less commonly, this color is observed in pronounced jaundice.
• Gray or black: a consequence of inhaling coal dust (anthracosis in miners and workers in hazardous industries).

Sputum odor: Normally, the secretion has no pronounced odor. An unpleasant, putrid, or foul odor is an alarming sign. It indicates the breakdown of lung tissue (gangrene, cancer, abscess), anaerobic infection, or the combined action of anaerobic and streptococcal flora.

Three-layer phenomenon

In conditions accompanied by congestion or tissue breakdown (e.g., in pulmonary edema or alveolar cell carcinoma with protein transudate), sputum stratification is observed. If such secretion is collected in a clear container and allowed to settle, it will divide into three distinct layers:

1. Top layer: foamy serous fluid.
2. Middle layer: largest in volume, liquid. Contains leukocytes, erythrocytes, and bacteria.
3. Bottom layer: purulent sediment. Microscopically, neutrophils and massive bacterial flora are found in it.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Microscopic sputum examination
• Cytological evaluation and cell identification
• Bacteriological examination and Gram staining
• Pathological impurities in sputum (blood, casts, solid particles)

Other topics in the "Respiratory System" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.