Kidney abscess

A kidney abscess is a limited inflammation with melting of the renal tissue and the formation of a purulent cavity surrounded by a granulation ridge that separates the purulent focus from the surrounding healthy tissue.

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Causes kidney abscess

A renal abscess may also be a consequence of the fusion of pustules in apostematous pyelonephritis, abscess formation of a carbuncle. A renal abscess may be a direct consequence of a calculus in the pelvis or ureter, or form after surgery on the renal tissue for urolithiasis. In this case, a severe course of the postoperative period and the formation of a urinary fistula are noted. A. Ya. Pytel et al. (1970) particularly highlight an abscess that develops in urinogenic (ascending) pyelonephritis. In this case, the pathogen penetrates the kidney through the renal papilla. In some cases, the process is limited to the papillae, while in others it spreads to other tissues, forming a large solitary abscess involving the adjacent perirenal tissue. With such an abscess, lumps of sequestered renal tissue are found among the accumulation of pus.

In some cases, when the abscess is located within the upper or lower segment of the kidney, sequestration of a large area of the renal parenchyma may occur. Cases of abscess formation after a stab wound to the kidney have been described. So-called metastatic renal abscesses are also observed, which occur when infection is introduced from extrarenal foci of inflammation. The source of infection is most often localized in the lungs (destructive pneumonia) or heart (septic endocarditis). Renal abscesses are rarely multiple and bilateral.

The resulting abscess of the renal cortex may open through the renal capsule into the perirenal tissue and form a paranephric abscess. Sometimes it breaks through into the calyceal-pelvic system and is emptied through the urinary tract. In some cases, the abscess spills into the free abdominal cavity or becomes chronic, simulating a renal tumor.

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Symptoms kidney abscess

Symptoms of a kidney abscess may resemble those characteristic of acute pyelonephritis, which complicates timely diagnosis. Before surgery, the correct diagnosis is established only in 28-36% of patients. If the urinary tract is passable, the disease begins acutely, with a sharp increase in body temperature, the appearance of pain in the lumbar region. The pulse and breathing become more frequent. The general condition of the patient is satisfactory or moderate.

When the passage of urine is disrupted, a picture of an acute purulent-inflammatory process in the kidney develops: body temperature of a hectic nature, stunning chills, frequent pulse and breathing, weakness, malaise, headache, thirst, vomiting, often hysteria of the sclera, adynamia, pain in the kidney area.

In bilateral renal abscesses, symptoms of severe septic intoxication and renal and hepatic failure predominate.

In case of solitary abscess, changes in urine are often absent. In case of patency of urinary tract, leukocytosis with neutrophilic shift of blood formula to the left, increased ESR are observed, in case of violation of urine passage, hyperleukocytosis of blood, severe anemia, hypoproteinemia. There are no changes in urine. or moderate proteinuria, microhematuria, bacteriuria and leukocyturia are observed (in case of abscess breakthrough into renal pelvis). During objective examination, an enlarged painful kidney is palpated. Pasternatsky's symptom is positive. In case of abscess location on the anterior surface of kidney and its spread to parietal peritoneum, symptoms of peritoneal irritation may be positive. Additional examination methods include survey urography, excretory urography, ultrasound, CT.

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Diagnostics kidney abscess

A general urogram may reveal a curvature of the spinal column toward the pathological process and the absence of the lumbar muscle shadow on the same side, and an enlarged kidney. Sometimes, a bulge of its outer contour is noted in the area of the abscess localization. Excretory urograms reveal a decrease in the excretory function of the kidney, compression of the renal pelvis or calyces, their amputation, and limited mobility of the kidney at the height of inhalation and after exhalation. CT is more informative, revealing a kidney abscess as a zone of decreased accumulation of contrast agent in the renal parenchyma in the form of single or multiple decay cavities that merge to form large abscesses. The abscess has the appearance of a rounded formation of increased transparency with an attenuation coefficient of 0 to 30 HU. A control study reveals a clear demarcation of the destruction focus from the renal parenchyma.

When pus breaks through into the renal pelvis, a cavity filled with RVC is visible on the urogram. Dynamic scintigrams reveal an avascular space-occupying lesion in the abscess area.

CT makes it possible to detect not only intrarenal or perirenal fluid accumulations, but also the presence of gas in the abscess cavity. This method can also be used to determine the routes of infection spread to surrounding tissues. These data can be useful in choosing surgical access and determining the scope of surgical intervention.

An ultrasound of the kidneys reveals the following signs of a kidney abscess:

• hypoechoic foci in the parenchyma with sizes from 10 to 15 mm and above;
• unevenness and bulging of the outer contour of the kidney at the site of the abscess;
• significant reduction in renal excursion;
• decreased echogenicity of the parenchyma.

Dopplerograms show no vascular pattern in the abscess area.

The clinical picture of metastatic renal abscesses is often dominated by symptoms of severe extrarenal inflammatory process (septic endocarditis, pneumonia, osteomyelitis, etc.). The basis for active search of renal metastatic abscesses should be "unmotivated" deterioration of the general condition of the patient.

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Treatment kidney abscess

Treatment of kidney abscess is surgical. Emergency surgery is indicated. Treatment of kidney abscess consists of decapsulation of the kidney, opening of the abscess, treatment of the purulent cavity with an antiseptic solution, wide drainage of this cavity and the retroperitoneal space. The abscess is most often located directly under the kidney's own capsule and is clearly visible. When localized in deep layers, bulging tissue is noted. As a rule, the formation is soft, fluctuates and upon palpation it is felt that it has a cavity with fluid.

Punctures and aspiration of pus help to establish the correct diagnosis. The contents of the abscess are sent for bacteriological examination and determination of the sensitivity of microorganisms to antibiotics. The abscess is opened with a wide incision. If the passage of urine from the kidney is disrupted, the operation is completed with a nephrostomy. Intensive antibacterial and detoxification therapy is continued in the postoperative period. In recent years, percutaneous puncture with evacuation of the contents, installation of drainage, and subsequent washing of the abscess cavity with antiseptics have been proposed for the treatment of renal abscess. In case of bilateral kidney damage, the operation is performed on both sides.

Metastatic renal abscesses are also subject to removal.

Prevention

Kidney abscess can be prevented if conservative and surgical treatment of patients with acute pyelonephritis is carried out in a timely manner.

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Forecast

The prognosis for conservative treatment of kidney abscess is unfavorable, as 75% of cases are fatal. With timely surgical intervention, patients usually recover.

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