An abscess is most often caused by the penetration of microorganisms (in most cases of staphylococci, epidermal streptococcus, bacteroids) into tissues and organs as a result of injuries (including operating theaters), superficial injections with short needles of pharmaceutical solutions of increased concentration or on an oil basis, and non-compliance of asepsis rules.
Etiology and pathogenesis
An abscess may occur with boils, carbuncles, lymphadenitis, hematoma suppuration. Favorable factors for the occurrence of this pathology are diabetes mellitus, obesity, vitamin deficiencies, immunodeficiency, imperfect or negligent techniques for performing operations and injections. There are external (exogenous) and internal (endogenous – metastatic) infections. The latter occurs in sepsis.
A feature of the abscess as a limited purulent process is the presence of a purulent membrane (shell) in it, the inner wall of which is lined with granulation tissue. The purulent membrane separates the purulent-necrotic process from nearby tissues that produce exudate. This property of tissues adjacent to the abscess indicates adequate adaptation and protective reactions of the body. In case of such serious diseases as dystrophy, diabetes mellitus, vitamin deficiency, malignant tumors, it is difficult to avoid the purulent process in nearby tissues. Taking into account these diseases, an abscess has a tendency to spread.
An abscess is formed in dead tissues in which microchemical processes of autolysis take place (in case of injury, vascular thrombosis), or in large-scale infected living tissues. In the initial period of abscess development, a limited area of tissue is infiltrated with leukocytes, connective tissue cells, and exudate. Under the action of enzymes, tissues gradually melt, as a result of which a purulent exudate is formed, around which granulation tissue, enriched with new capillary vessels, actively develops (due to the endothelium of destroyed capillaries, fibroblasts, macrophages). Initially, the walls of the abscess are covered with purulent-necrotic layers. Over time, demarcation inflammation occurs along its periphery. Gradually, granulation tissue matures and two layers are formed in the purulent membrane: the inner – granulation (vascular) and outer – mature connective tissue.
An abscess may result in a spontaneous breakthrough out into the body cavity, into a hollow organ, or scarring. An abscess is very rarely encapsulated. At the same time the pus thickens, cholesterol crystals fall out of it, on the border of the abscess a thick scar capsule is formed. Sometimes the abscesses that occur around animal parasites or their larvae (cysts) are petrified. If foreign bodies or sequesters are present in the abscess cavity, long-healing fistulas may be formed.
The nature of pus (color, texture, odor) is determined by the type of pathogen: fetid odor, dirty gray color characteristic of putrid flora, thick yellow-green pus – for staphylococcus, blue-green with a sweetish sugary smell – for blue pus bacillus, scanty, liquid and hemorrhagic, with droplets of fat present in it – for bacteroids.
Common symptoms are fever, weakness, headache, lack of appetite, leukocytosis, a shift in blood count to the left, an increase in ESR. Severe abscess with dominance of general intoxication is due to the absorption of toxic substances from the source of inflammation (toxic-resorptive fever), as well as sepsis.
Differential diagnosis of an abscess is performed with hematomas, aneurysm, cysts, disintegrating tumors, and cold abscess (with tuberculosis). Palpation with the definition of a symptom of purulent softening is of diagnostic importance; percussion with listening to the tympanic sound of gassing; X-ray examination, during which the horizontal level of the fluid and the gas bubble above it are often determined inside the abscess; Ultrasound examination, during which an abscess is defined as a hypo- or anechoic formation of a heterogeneous structure with hyperechoic inclusions of necrotic tissues, relatively clear but somewhat blurred outlines, oval or rounded, with tangential shadows of the pattern; diagnostic puncture, by which the abscess contents are selected for bacteriological examination. However, this diagnostic method is considered invasive, as it can lead to additional infection or injury to internal organs.
In the stage of infiltration of an abscess, conservative methods are used: exercise restriction, physiotherapeutic procedures (UHF, electrophoresis of drugs, bio-galvanization), vibroacoustic therapy (as it facilitates the rapid resorption of the abscess). The melting of the infiltrate and the formation of a cavity is an absolute indication for surgical treatment. An abscess is cut and drained regardless of its location. Do not cut cold abscesses (tuberculosis nodules), because they are always infected. Anesthesia should be general, an abscess incision should be adequate for its further revision, it is possible to use the needle left in the abscess after a preliminary diagnostic puncture, as a drainage. During an operation for an abscess, pus is removed from it, in a blunt way without damaging the purulent membrane, purulent necrotized sequesters are removed, pockets and partitions are eliminated, and a single cavity is formed, which is washed with antiseptic solutions. If necessary, it is possible to perform an additional incision (contraception) to create more efficient drainage. In the postoperative period, the treatment of an abscess is similar to the one of purulent wounds, taking into account the stage of development of the wound process.