Renal carbuncle is a localized purulent–necrotic process that is a complication of acute pyelonephritis or occurs due to hematogenic infection of the urinary system. It is manifested by a sharp intoxication of the body (fever, vomiting, weakness) and lower back pain. There may be signs of damage to other organs – the myocardium, liver, adrenal glands. Diagnostics is performed by ultrasound, kidney CT, urography, laboratory blood and urine tests play an auxiliary role. Treatment includes antibiotic therapy, autopsy and drainage of a purulent focus.
Meaning
Renal carbuncle is one of the forms of purulent lesions of the urinary system. Its peculiarity is the predominance of necrosis in pathogenesis, resulting in a particularly pronounced intoxication of the body. Often combined with purulent pyelonephritis and apostematous nephritis, it is believed that these three conditions are different stages of the same purulent-inflammatory pathological process.
In women, the disease occurs somewhat more often, which is due to the anatomical features of the urinary system, facilitating the upward penetration of infection. Sometimes there is a certain seasonality of morbidity with an increase in the number of cases in the cold season, the provoking factor is hypothermia.
Causes
The cause of the renal carbuncle is infection of the kidney medulla with a purulent bacterial microflora – most often with E. coli, staphylococci or streptococci. The infection can penetrate both directly from the external environment (through the urinary tract), and hematogenically, from other purulent or inflammatory foci. In the first case, the appearance of a carbuncle is often preceded by pyelonephritis, in the second – apostematous nephritis develops first. Urodynamic disorders facilitate the formation of a purulent-necrotic focus. The following groups of predisposing factors are distinguished:
- Inflammation of the urinary tract. Urethritis, cystitis and pyelonephritis, especially caused by purulent microflora, cause the formation of an infection reservoir. Penetrating into the kidneys, microbes can provoke a purulent-necrotic process in them.
- The presence of purulent foci in the body. Diseases of bacterial origin can be complicated by the development of a renal carbuncle. In this case, there is a hematogenic transfer of pathogens, often occurring against the background of weakened immunity.
- Urodynamic disorders. With a difficult outflow of urine, favorable conditions are created for the accumulation of microorganisms in the kidneys. Microbes can penetrate from the lumen of the tubules into the interstitial space and cause rapid inflammation. This phenomenon is noted in urolithiasis, urethral strictures, scarring of the calyx-pelvic system.
The reasons for which in some cases there is apostematous nephritis, and in others – an abscess or carbuncle are reliably unknown. It is assumed that the main role is played by the reactivity of inflammatory processes, immunogenicity and virulence of the pathogen, local hypothermia and other factors. The role of vascular reactions has not been studied – perhaps, against the background of arteriole spasm, as a result of inflammation, a heart attack is formed first, and then necrosis of the affected area of the kidney, accompanied by a purulent lesion of the renal tissue characteristic of the carbuncle.
Pathogenesis
The pathogenetic processes leading to the carbuncle of the kidney differ depending on the path of penetration of pathogenic microbes into the excretory organs. With pyelonephritis or ascending infection, bacteria initially enter the collecting tubules and convoluted tubules of the second order. The pathogen causes the destruction of the epithelial cover, penetrates through the basement membrane into the interstitial substance and triggers a violent inflammatory reaction. The resulting infiltration shaft complicates the blood supply to the affected area, provoking necrotic processes. Carbuncles developing by such a mechanism do not reach significant sizes, their manifestation often goes unnoticed against the background of purulent pyelonephritis.
With the hematogenic pathway of bacterial microflora, partial obturation of the branches of the renal artery by septic emboli is observed. The sources of the latter are inflammatory foci in other parts of the body. There is a septic kidney infarction, the volume of which depends on the caliber of the obstructed vessel. At the same time, pathogenic microorganisms that are part of the embolus cause purulent inflammation. The combination of immune and necrotic processes leads to the appearance of a renal carbuncle. The size and localization of the lesion depend on the volume of ischemic renal tissue.
Symptoms
There are two main forms of the disease that differ in their course and symptoms – violent (explicit) and latent. A typical clinical picture of a carbuncle is characterized by a sharp onset with an increase in body temperature to 40 degrees, chills, severe general condition (vomiting, delirium, psychomotor agitation). There is pain in the lumbar region, which then shifts towards the affected kidney, swelling may be detected in the area of its projection. The inflammatory process is able to spread to the parietal peritoneum with the formation of a picture of an “acute abdomen”.
The latent form of the renal carbuncle is similar in its symptoms to diseases of other organs and systems, may not be accompanied by a significant rise in body temperature. Signs of damage to the cardiovascular system with tachycardia, arrhythmia, and an increase in blood pressure often come to the fore. Some patients have mainly abdominal symptoms – painful sensations in the epigastrium, nausea, vomiting, diarrhea. Severe intoxication of the body by the products of tissue breakdown as a result of necrosis can cause liver damage, manifested by jaundice and signs of renal-hepatic insufficiency.
Changes in diuresis are rarely observed, especially in latent and atypical forms of pathology. Specific manifestations of kidney damage are usually absent, even Pasternatsky’s symptom is often negative. Renal insufficiency occurs only in 10-20% of patients, may be caused by a bilateral lesion. Inflammation often passes from the kidneys to other organs (adrenal glands, pleura) with the appearance of appropriate symptoms.
Complications
Renal carbuncle is characterized by a wide range of complications, because due to difficult diagnosis, the disease often turns into a neglected form. A serious consequence of pathology is septic shock caused by intoxication of the body with products of purulent melting and necrosis of renal tissue. Sometimes an embolism of the branches of the pulmonary artery and cerebral vessels develops, often leading to a fatal outcome. The threat is the spread of the purulent process to the surrounding organs – the adrenal glands, abdominal structures, pleura. In weakened patients, systemic infection (sepsis) is possible.
Diagnostics
The definition of the disease is difficult due to the lack of specific symptoms and its “masking” under the pathology of other organs. It is possible to identify a renal carbuncle only according to the clinical picture in only a part of patients, in other cases, a number of diagnostic procedures are necessary to make a diagnosis. Often, symptoms are mistakenly interpreted as a consequence of diseases of the respiratory, cardiovascular, digestive and other systems. In the patient’s anamnesis, attention is paid to the presence of purulent processes and inflammation of the urinary tract. To diagnose a carbuncle in clinical urology, the following diagnostic methods are used:
- Ultrasound. Ultrasound of the kidneys determines a hypoechoic heterogeneous formation of various sizes in the thickness of the organ (often in the brain layer). There may be some increase in the affected kidney and swelling of the paranephral fiber. The ultrasound of the renal vessels confirms a decrease in the volume of blood flow in the area of the pathological focus.
- Radiological methods. Excretory urography indicates a decrease in the functional activity of the kidney in combination with the deformation of the heart. Sometimes the changes are noticeable on an overview radiograph of the abdomen – there is an increase in one of the renal segments and blurring of the contours of the lumbar muscle.
- CT of the kidneys. Multispiral CT with contrast is considered the gold standard in the diagnosis of renal carbuncle. If it is present in the images, an area is determined that practically does not accumulate contrast and is surrounded by a rim with a higher density. This distinguishes the purulent process from a tumor (it delays the contrast agent) or a cyst (it does not have a characteristic rim).
- Laboratory tests. Blood test reveals the presence of nonspecific signs of inflammation – high leukocytosis with neutrophilia, increased ESR. In the analysis of urine, changes are initially insignificant (proteinuria, single leukocytes), when a carbuncle breaks into the cups or pelvis of the kidney, pronounced pyuria develops.
The typical form of the disease should be differentiated from other pathological processes in the kidneys – tumors, abscess, infection and suppuration of the cyst, severe pyelonephritis. Latent varieties of the disease often manifest as lesions of other organs, which requires a careful approach to differential diagnosis. With an atypical picture, it is necessary to exclude acute cholecystitis, pancreatitis, heart pathology, subdiaphragmatic abscess.
Treatment
The treatment of the disease is performed by surgical, less often by conservative methods. Due to the delayed determination of pathology, emergency operations are often required. The intervention consists in decapsulation of the kidney, opening, drainage of the purulent focus. Sometimes drainage is additionally installed in the perinephrine fatty tissue. With multiple carbuncles in one kidney or the destruction of a significant volume of organ tissues, nephrectomy is indicated. After surgery, antibacterial agents are prescribed to prevent infectious complications.
Conservative therapy of the renal carbuncle is permissible only at the very initial stages of pathology development or when the contents break into the pelvis (natural drainage) and there are absolute contraindications to surgical intervention. Intensive antibiotic therapy is used, the effectiveness of which increases with the correct selection of the drug. To do this, at the diagnostic stage, the pathogen is isolated and its sensitivity to antibacterial drugs is determined.
A method of carbuncle treatment by combined administration of antibiotics and cryoprecipitate containing the 8th coagulation factor has been developed. This compound reduces ischemic manifestations in the purulent focus, promotes the penetration of antimicrobial agents into it.
Prognosis and prevention
With timely detection and emergency surgery, the prognosis of the renal carbuncle is favorable. There may be a slight decrease in the activity of the urinary system due to scarring and a decrease in the volume of the organ, therefore, patients after recovery need regular supervision of a nephrologist. The prognosis worsens in the presence of multiple carbuncles, the spread of the process to neighboring structures, the appearance of septic emboli in the bloodstream. To prevent pathology, purulent-inflammatory diseases of the kidneys and other organs should be fully treated.