Post injection abscess is a limited purulent–inflammatory focus at the injection site of the drug. The abscess is characterized by the appearance of local swelling and redness of the skin, gradually increasing in the volume of compaction, an increase in pain of a bursting nature, fluctuation. The diagnosis is made on the basis of anamnesis and clinical picture (the appearance of a purulent-inflammatory focus at the site of intramuscular and intravenous injections), ultrasound data, MRI of soft tissues. At the stage of infiltration, conservative treatment is effective. The formed abscess is opened surgically and drained.
Cases of post-injection abscessing of soft tissues occur in people of all ages, more often in obese, overweight patients. Most of the postinjection ulcers develop in the buttocks, since the gluteal muscle is used most often for parenteral administration of drugs. Children have a large proportion of shoulder abscesses as a result of vaccinations. Intravenous drug administration is the most common cause of the formation of a focus of suppuration in the area of the ulnar fossa. Post-injection abscesses of this localization account for 69% of all cases of purulent-inflammatory processes of soft tissues in drug addicts.
For the formation of a post-injection focus of suppuration, it is not enough just for bacteria to enter the tissues. The human immune system is able to cope with a small number of pathogenic and opportunistic microorganisms that have overcome the protective barrier of the skin. For the development of an abscess, other contributing factors must be present:
- High pathogenicity of microorganisms. Different types of bacteria have different rates of cell division and the ability to resist the immune system. Staphylococcus aureus or Pseudomonas aeruginosa more often cause the formation of a post-injection abscess than conditionally pathogenic species that make up the microflora of the skin.
- Weakening of immunity. It may be a consequence of a banal seasonal acute respiratory infection or a serious concomitant disease. The probability of developing abscesses is higher in patients with diabetes mellitus, severe cardiovascular, endocrine, and infectious diseases.
- Local circulatory disorder. This is facilitated by the simultaneous introduction of significant volumes of the solution into the muscle (more than 5 ml), simultaneous administration of several drugs into one buttock. The first sign of abscessing is a significant seal at the injection site. The risk of postinjection suppuration increases in bedridden patients, patients with bedsores.
- Local irritating effect of drugs. Not only bacteria, but also chemicals can provoke purulent melting of tissues. Erroneous intramuscular administration of drugs intended for intravenous or subcutaneous infusions can cause necrosis and inflammation. An individual reaction can be given by a drug that is allowed for intramuscular use, but is not suitable for a specific patient.
- Violation of injection technique. Factors in the development of post-injection complications are non-compliance with the rules of asepsis and antiseptics, the use of the wrong solvent, too rapid introduction of solutions, incompatibility of different drugs. One of the consequences of incorrect technique can be damage to vessels of various diameters with a needle. Blood clots are a substrate for the reproduction of microorganisms and the formation of a post-injection abscess.
The development of an inflammatory reaction is based on the release of a large number of lysosomal enzymes from damaged and dead cells into the extracellular environment, which alter the metabolism in the pathological focus. In the necrosis zone, metabolism slows down, and in the areas adjacent to it sharply increases, which leads to an increase in oxygen and nutrient consumption, the development of acidosis due to the accumulation of under-oxidized products: lactic, pyruvic and other acids.
The blood supply to the pathological focus changes: the blood flow increases and the outflow slows down. This explains the redness of the affected area. Blood vessels expand, the permeability of capillaries to blood plasma and cells increases. Leukocytes and macrophages enter the tissues. Local inflow of fluid leads to the formation of edema. Compression of nerve endings provokes pain. This is the stage of infiltration, when there is no pus in the focus of inflammation yet. Under favorable conditions at the stage of infiltration, the changes are reversible.
At the stage of abscessing, dead tissues and dead cells of the immune system form pus. The post injection abscess is located in the center of the focus of inflammation. Pus clots are separated from healthy tissues by a granulation shaft. The pus does not dissolve. It is possible to eliminate inflammation only if conditions are created for the outflow of the contents of the abscess.
The pathological focus is formed within a few days. The onset of the disease may go unnoticed for the patient due to the insignificant degree of severity of symptoms. The first manifestations of developing purulent inflammation can be masked by pain and swelling of injection sites caused by a physiological reaction to the administration of drugs. It is possible to distinguish between the formation of an inflammatory infiltrate and a normal reaction for intramuscular injections with careful attention to your feelings.
The pain after the injection is immediately sharp bursting, then aching. Its intensity decreases quite quickly. The pain of a maturing abscess is constantly increasing. Normally, the seal after injections is fairly uniform, its temperature does not differ from the temperature of the surrounding areas, the skin above the seal is of the usual color. The addition of an inflammatory reaction is marked by a noticeable local increase in temperature. The increase in swelling and pain in the buttock leads to the fact that it is impossible to sit on the affected side. Unpleasant sensations increase when walking and performing other movements. Pressing on the area of the abscess is sharply painful, whereas the usual seal can be felt without provoking pronounced unpleasant sensations in the patient.
Post injection abscess is characterized by fever with an increase in body temperature to 39-40oC. However, it is not necessary to focus only on this symptom. If the inflammatory focus develops against the background of ongoing injections of nonsteroidal anti-inflammatory drugs with analgesic and antipyretic effects, then hyperthermia is absent.
The rapid development of infection in the focus can provoke the formation of pus congestion in the intermuscular spaces. The spread of bacteria in the tissues causes the development of extensive phlegmon of the buttock, hip, shoulder. There is a danger of the formation of long-term non-healing soft tissue fistulas and rectal fistulas. The breakthrough of pus into the bloodstream causes sepsis, pericarditis, osteomyelitis, DIC syndrome – in these cases, even with the appointment of adequate treatment, the outcome for the patient may be unfavorable.
The diagnosis does not cause difficulties for the consulting surgeon. The characteristic pentad of signs of inflammation (redness, swelling, pain, fever, dysfunction) at the injection site allows you to quickly determine the nature of the pathological process. A positive symptom of fluctuation indicates the presence of fluid in the focus, which is an indication for surgery. To confirm the diagnosis of a post-injection abscess in doubtful cases:
- Ultrasound of the abscess. In three out of four cases, the accumulation of pus is localized in the thickness of the muscle and the intermuscular spaces and only in 25% of cases in the subcutaneous tissue. The shape of the purulent cavity is oval. Its largest radius is located parallel to the axis of the body. Ultrasound of soft tissues makes it possible to distinguish between infiltration and suppuration with a deep location of the pathological focus in the tissues, to identify congestion and “pockets” that may go unnoticed during surgery.
- MRI of the affected area. It is prescribed in cases when the informative value of ultrasound is insufficient to make a correct diagnosis. Soft tissues, bones, and internal organs of the studied area are visualized on the images obtained by magnetic resonance imaging. This allows you to detect pathological changes, conduct differential diagnostics, and identify complications.
- Laboratory tests. In order to select an effective antibacterial drug, the contents of the abscess can be seeded on the flora and its sensitivity to antibiotics. It is mandatory to perform general and biochemical blood tests, a general urine test to exclude pathology from the internal organs.
Approaches to the treatment of abscesses at the stages of infiltration and suppuration are radically different. In the first case, conservative therapy is indicated, in the second – surgical operation. The basic principles of conservative local treatment of infiltrates can be successfully applied to the rapid resorption of post-injection seals that do not have signs of inflammation.
- General treatment. Its volume is determined by the doctor based on the clinical picture. Anti-inflammatory drugs and antibiotics are aimed at resolving the inflammatory process. Additionally, infusion therapy may be prescribed to combat intoxication.
- Local therapy. It involves applying Vishnevsky ointment to the affected area or using compresses with dimexide. At the initial stages, it is allowed to perform an iodine grid. If the condition does not improve during the day, it is advisable to use more effective drugs.
- Physical therapy. All thermal effects are prohibited. Electrophoresis of anti-inflammatory drugs, diadynamic currents are effective. Physiotherapy procedures are prescribed simultaneously with local and general anti-inflammatory treatment.
- Surgical operation. The opening and drainage of the purulent cavity is carried out under local anesthesia. Under general anesthesia, the operation is performed when the post-injection abscess is located deep in the tissues. In the postoperative period, general and local conservative treatment is carried out, physiotherapy procedures are prescribed.
Prognosis and prevention
The prognosis of postinjection suppuration is favorable, provided timely treatment for medical help. Otherwise, complications of the disease may develop. Spontaneous opening and emptying of a deep abscess is impossible, and recovery does not occur without evacuation of pus from the cavity. Surgical opening of the abscess allows you to solve the problem in one day.
Prevention of post-injection complications involves the administration of drugs parenterally in medical institutions by medical personnel, refusal of self-medication. It is advisable to change the places of administration of solutions during the course appointment: if seals have already formed on the buttocks, drugs can be injected into the muscles of the anterior surface of the thigh. You can not inject funds for intravenous infusions into the muscles, even if the veins are thin and brittle. It is advisable to make the injection course as short as possible, continuing treatment with taking pills.