Macroscopic examination of sputum

Macroscopic examination of sputum in patients with pneumonia has important diagnostic value, often helping to establish the nature of the pathological process and possible complications (for example, bleeding or suppuration).

The amount of sputum in respiratory diseases can vary widely (from 10 to 500 ml or more per day) and is determined mainly by two factors:

1. the nature and degree of activity of the pathological process in the lungs and
2. the ability to easily cough up the resulting sputum.

A relatively small amount of sputum (no more than 50-100 ml per day) is typical for most patients with pneumonia and other inflammatory lung diseases (acute tracheitis, acute and chronic bronchitis, etc.).

A significant increase in the amount of sputum (more than 150-200 ml per day) is usually observed in diseases accompanied by the formation of a cavity communicating with the bronchus (lung abscess, tuberculous cavity, bronchiectasis), or tissue decay (gangrene, decaying lung cancer, etc.). It should be noted in this regard that sometimes in these patients the amount of sputum may decrease due to a violation of the drainage of the inflammatory focus.

In severe cases of pneumonia and elderly patients, the cough reflex is often suppressed, as a result of which sputum is secreted in small quantities or is absent altogether.

The color of sputum depends on the composition of pathological tracheobronchial secretions and the presence of various impurities (for example, blood impurities).

The main reasons for changes in the color of sputum in pneumonia and other lung diseases

Color and character of sputum	The nature of the pathological process
Colorless, transparent (mucous sputum)	Many acute diseases of the lungs, trachea and bronchi (especially in the initial stage), accompanied mainly by catarrhal inflammation. Often - chronic diseases in the remission stage
Yellowish tint (mucopurulent)	The presence of a moderate amount of pus in sputum. Characteristic of most acute and chronic lung diseases at a certain stage of inflammation development
Greenish tint (mucopurulent or purulent)	Stagnation of purulent sputum, accompanied by the breakdown of neutrophilic leukocytes and the release of the enzyme verdoperoxidase, the transformation of the iron porphyrin group of which causes a greenish tint to the sputum
Yellow (canary) color of sputum	The presence of a large number of eosinophils in sputum (for example, in eosinophilic pneumonia)
Rusty color	Penetration of erythrocytes into the lumen of the alveoli by diapedesis and the release of hematin from disintegrating erythrocytes (most characteristic of lobar pneumonia)
Pinkish color of serous sputum	Admixture of slightly changed erythrocytes in serous sputum in alveolar pulmonary edema
Other shades of red (scarlet, brown, etc.)	Signs of more significant blood impurities (hemoptysis, pulmonary hemorrhage)
Blackish or greyish color	Coal dust impurities in sputum

It should be borne in mind that the appearance of blood impurities in sputum, regardless of the nature of the underlying pathological process (catarrhal, purulent or fibrinous inflammation, tumor, etc.), significantly changes the color of the sputum (see below).

The smell of sputum. Usually, serous and mucous sputum has no smell. A foul, putrid smell of freshly secreted sputum indicates:

1. about putrefactive decay of lung tissue in lung abscess, lung gangrene, and decaying lung cancer;
2. about the decomposition of sputum proteins (including blood proteins) when it remains in cavities for a long time (lung abscess, less often bronchiectasis), mainly under the influence of anaerobic flora.

Character of sputum. Depending on the consistency, color, transparency, odor and other physical signs revealed during macroscopic examination, there are four main types of sputum:

1. Mucous sputum is colorless, viscous, odorless. It occurs in the initial stages of inflammation or when its activity subsides.
2. Serous sputum is also colorless, liquid, foamy, odorless. It appears, as a rule, in alveolar pulmonary edema, when, as a result of increased pressure in the pulmonary circulation or increased permeability of the vascular wall during inflammation, transudation of protein-rich blood plasma into the lumen of the respiratory tract increases. Due to active respiratory movements (suffocation, dyspnea), the plasma foams and is released as a foamy liquid, sometimes diffusely colored pink, which indicates a significant increase in the permeability of the vascular wall and bleeding of the per diapidesum type.
3. Mucopurulent sputum - viscous, yellowish or greenish in color - is usually found in many respiratory diseases, including pneumonia. In some cases, mucopurulent sputum may have a mild unpleasant odor.
4. Purulent sputum is liquid or semi-liquid, greenish or yellowish in color, often with an unpleasant fetid odor. It occurs in acute or chronic suppurative processes in the lungs and bronchi, in the decay of lung tissue (abscess and gangrene of the lung, bronchiectasis, decaying lung cancer, etc.). When purulent sputum is left to stand, two or three layers are usually formed. Purulent sputum in some lung diseases (abscess, gangrene of the lung, bronchiectasis, purulent bronchitis) separates into two or three layers when left to stand for several hours.

Two-layered sputum is more common in lung abscesses. The upper layer consists of serous foamy fluid, and the lower layer consists of greenish-yellow opaque pus.

Three-layer sputum is most typical for gangrene of the lung, although sometimes it can appear in patients with bronchiectasis and even putrefactive bronchitis. The upper layer of such sputum consists of foamy colorless mucus containing a large number of air bubbles, the middle layer - of a turbid mucous-serous liquid of a yellowish-greenish color, the lower - of yellow or greenish opaque pus.

Hemoptysis. Blood in sputum is of great diagnostic importance, often indicating the development of serious complications. Depending on the degree and nature of damage to the lung tissue and respiratory tract, blood in sputum (hemoptysis - haematoptoe) may be different: 1) blood streaks, 2) blood clots, 3) "rusty" sputum, 4) diffusely colored pink sputum, etc. If pure scarlet blood without any mucus or pus is released during coughing, this is called pulmonary hemorrhage (haematomesis). Hemoptysis (haematoptoe) is the release of sputum with blood. In pulmonary hemorrhage (haematomesis), pure scarlet blood is released during coughing (tuberculosis, lung cancer, bronchiectasis, traumatic injuries, etc.).

In pneumonia, especially in lobar pneumonia, it is also possible to have blood in the sputum in the form of "rusty" sputum, streaks or blood clots. Hemoptysis and pulmonary hemorrhage may also occur in other respiratory diseases. However, it should be borne in mind that in real clinical practice, blood in the sputum may often have other characteristics. For example, contrary to popular belief, "rusty" sputum may occur not only in lobar pneumonia (typical cases), but also in focal and influenza pneumonia, pulmonary tuberculosis with caseous decay, pulmonary congestion, pulmonary edema, etc. On the other hand, in lobar pneumonia, streaks or even blood clots may sometimes appear in the sputum, or, conversely, it does not have any blood impurities and is mucous or mucopurulent in nature.

The main causes of hemoptysis and the most typical type of sputum

Main reasons	Nature of blood admixture
Bronchiectasis, chronic purulent bronchitis	Most often in the form of streaks or clots of blood in sputum of a purulent or mucopurulent nature
Lobar pneumonia	"Rusty" sputum
Abscess, gangrene of the lung	Purulent-bloody, semi-liquid, spit-like consistency, abundant sputum of brown or red color with a sharp putrid odor
Lung cancer	Bloody, sometimes gelatinous sputum (like "raspberry jelly")
Pulmonary tuberculosis	Blood streaks or clots in mucopurulent sputum; when a cavity forms, copious bloody sputum of brown or red color may appear
Pulmonary infarction	Blood clots or diffusely brown-stained sputum
Alveolar pulmonary edema	Diffusely stained pink frothy serous sputum
Staphylococcal or viral focal pneumonia	Blood streaks or clots in mucopurulent sputum, and sometimes “rusty” sputum
Actinomycosis of the lung	Blood streaks or clots in mucopurulent or purulent sputum

It should be remembered that almost all of the diseases listed in the table may lead to the development of massive pulmonary hemorrhage.

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