Apostematous pyelonephritis

Apostematous pyelonephritis is a purulent-inflammatory urological disease with the formation of multiple small pustules (apostemes) in the parenchyma, mainly in the cortical substance of the kidney. This is one of the types of acute purulent pyelonephritis.

[1], [2]

Causes of the apostematous pyelonephritis

There are four pathogenetic stages leading to the development of apostematous nephritis.

• Repeated short-term bacteremia. Microorganisms can enter the bloodstream through pyelolymphatic and pyelovenous reflux from extrarenal foci of infection in the organs of the urinary system. A small infection does not lead to the development of sepsis. Bacteria perish, and the products of their decay are excreted in the urine. In this case, the membrane of hemocapillary glomeruli is damaged, which becomes permeable to microorganisms.
• With repeated entry of bacteria into the blood, some of them can pass through the membrane and enter the lumen of the capsule, and then into the lumen of the convoluted tubule of the first order. If the outflow through the intrarenal tubules is not disturbed, the process may be limited to the appearance of bacteriuria.
• With intracinal urine stasis or slowing down the outflow along the tubules (obstruction of the urinary tract, relative dehydration of the organism), microorganisms trapped in the lumen of the glomerulus capsule and the convoluted tubule of the first order begin to multiply rapidly. Despite the contact with the foci of infection, in these departments the epithelium and basal membrane are not violated.
• As you move along the tortuous canal, the multiplying microorganisms enter urine, which is an unfavorable environment for them. The massive aggression of bacteria against the relatively weakly protected cells of the tubular epithelium begins. At the same time, a violent, but delayed, leukocyte reaction occurs, accompanied by the penetration of a large number of leukocytes into the lumen of the tubules. The cells of the epithelium decay and perish. The basal membrane is torn in many places. The strongly infected contents of the convoluted tubule of II order penetrate into the interstitial tissue of the kidney. If the microflora is sufficiently virulent, and the protective reactions of the body are weakened, the primary peritubular infiltrates are suppressed. Pewniki are localized in the surface layers of the cortical substance of the kidney, since it is here that most of the twisted tubules of the second order are located. The abscesses are small (peritubular infiltrates can not reach large sizes), there are many of them (massive invasion of infection occurs through a significant number of glomeruli). They are poorly delimited by the leukocyte and connective tissue shaft. Due to insufficient isolation, there is a significant resorption of the products of purulent inflammation. This can lead to both local (acute degeneration, down to the tubular epithelial necrosis), and to general disorders due to acute infectious-septic toxemia. Among the general disorders, changes in the function of the cardiovascular, nervous respiratory systems, and the liver are at the forefront. Possible secondary (toxic-septic) degenerative changes in the contralateral kidney, up to total necrosis of the tubular epithelium and cortical necrosis, leading to the development of acute renal failure. With prolonged flow of apostematous nephritis, other manifestations of the pathological process can be observed. With a satisfactory defense response and the usual virulence of the flora, individual apoemes merge, separated by a denser cellular and then connective tissue shaft, becoming abscesses. At the same time, the fibroplastic reaction is enhanced. The connective tissue of the kidney grows and coarsens. It creates focal infiltrates, consisting of lymphocytes and plasma cells. Thickening of the intima of many of the intrarenal arteries. Some veins are thrombosed. Because of this, there may be zones of relative ischemia of the kidney parenchyma. In other cases, the inflammatory process extends to the entire connective tissue stroma of the organ, which undergoes diffuse massive infiltration by polymorphonuclear leukocytes. That is why there are severe changes in the intrarenal vessels (thrombosis of the arteries) with the formation of zones of local ischemia. Often superinfection can lead to the emergence of a background of apostematous nephritis of the kidney carbuncle.

The kidney, afflicted with apostematous nephritis, is enlarged, blue-cherry or blue-purple. The fibrous capsule is thickened, the pericarp adipose capsule is edematous. After removing the capsule, the surface bleeds. It shows multiple foci of inflammation, having the appearance of pustules of 1-2.5 mm in diameter, located singly or in groups. With a large number of pustules, the kidney becomes flabby (due to swelling and degeneration of the parenchyma). Small pustules are seen not only in the cortex, but also in the brain substance (in rare cases they are contained only in the brain substance.)

[3]

Symptoms of the apostematous pyelonephritis

Symptoms of apostematous nephritis largely depend on the degree of violation of the passage of urine. In hematogenous (primary) apostematous nephritis, the disease manifests itself suddenly (often after overcooling or overworking of the transferred intercurrent infection). The disease begins with a sharp rise in body temperature (up to 39-40 ° C or more), which then rapidly decreases; tremendous chills, excessive sweating. There are symptoms of severe intoxication: weakness, tachycardia, headache, nausea, vomiting, adynamia, lowering blood pressure. At 5-7th day, pain in the lumbar region, which at the beginning of the disease is dull, increases. This is due to the involvement of the fibrous capsule in the kidney or a breakthrough pustules.

Usually, from the very beginning of the disease, pain is determined by palpation of the corresponding area, an increase in the kidney. In primary apostematous nephritis, the process can be bilateral, but the disease does not always start simultaneously from both sides. In the urine of change, there may not be a first. Later, leukocyturia is revealed. Proteinuria, true bacteriuria, microhematuria. The blood picture is typical for sepsis: hyperleukocytosis, a shift of the blood formula to the left, toxigenic granularity of leukocytes, hypochromic anemia, increased ESR, hypoproteinemia.

With prolonged flow, pain in the kidney area increases, there is stiffness of the muscles of the anterior abdominal wall on the side of the lesion and symptoms of irritation of the peritoneum. Infection by the lymphatic pathway can penetrate the pleura and cause the development of exudative pleurisy, empyema. There are septicemia, septicopyemia. You can observe the out-of-focus festering inflammation in the lungs (metastatic pneumonia), in the brain (brain abscess, basal meningitis), in the liver (abscess of the liver) and other organs. Develop acute renal failure and liver failure, jaundice occurs.

Apostematous nephritis with untimely and incorrect treatment can lead to urosepsis.

Secondary apostematous nephritis, in contrast to the primary, usually begins 2-3 days (sometimes later) after an attack of renal colic. Sometimes it develops against the backdrop of chronic obstruction of the urinary tract, and soon after the operation undertaken on the kidney or ureter for urolithiasis, after resection of the bladder, adenomectomy. Most often the process appears in the complication of the postoperative period with obstruction of the urinary tract, urinary fistula of the kidney or ureter. The disease begins with chills and pain in the lumbar region. In the future, primary and secondary apostematous nephritis proceed almost identically.

[4]

Forms

There are primary and secondary acute purulent pyelonephritis. Primary acute purulent pyelonephritis occurs against the background of the unchanged kidney, secondary - against the background of the existing disease (for example, urolithiasis). With obstruction of the urinary tract, the process is one-sided, with hematogenous origin - bilateral.

[5], [6], [7]

Diagnostics of the apostematous pyelonephritis

Diagnosis of apostematous nephritis is based on the analysis of anamnestic data, clinical signs, results of laboratory, radiographic and radiological methods of investigation. Compare the level of leukocytes in the blood taken from the finger and both lumbar regions (on the side of lesion the leukocytosis will be higher). On the overview radiograph of the lumbar region, the shadow of the affected kidney is increased, the contour of the lumbar muscle on this side is absent or smoothed, the curvature of the spinal column toward the affected organ is noted. Due to the inflammatory edema of the perineal tissue, the circumference around the kidney is visible. With the development of the pathological process in the pelvis or ureter, a shadow of the urinary stone is observed. Informative excretory urography. On urograms there is no mobility of the kidney during breathing. The urinary function is decreased or absent, the intensity of the shadow of the contrast agent secreted by the affected kidney is low, the organ is enlarged, the second-order calyces are not contoured or deformed. Enlargement of the kidney can be detected using a tomogram and ultrasound. When the echographic examination reveals the following symptoms of apostematous pyelonephritis:

• hypoechoic foci in the parenchyma with initial sizes up to 2-4 mm:
• thickening of the cortical and medullary layers of the kidney:
• increased echogenicity of the adrenal tissue:
• thickening of the capsule to 1-2 mm:
• deformation of calyx and pelvis;
• thickening of the walls of the pelvis.

In the Doppler study, local depletion of the vascular pattern is determined, more in the cortical layer.

With dynamic scintigraphy, a violation of vascularization is noted. Secretion and excretion. The obturation type of the renogram testifies to the pathological process in the kidney.

When spiral CT is performed, it is possible to obtain the following signs of the disease:

• a heterogeneous decrease in the density of the kidney;
• thickening of the parenchyma of the kidney.

Primary apostematous nephritis is differentiated from infectious diseases, subdiaphragmatic abscess, acute cholecystopancreatitis, acute cholangitis. Acute appendicitis, acute pleurisy.

[8], [9]

Treatment of the apostematous pyelonephritis

Treatment of apostematous nephritis consists in emergency surgery. The kidney is exposed by subcostal lumbootomy, then its decapsulation is performed. Opens out abscesses. Drains the retroperitoneal space, and with the broken passage, urine is provided for its free outflow by imposing a nephrostomy. Renal drainage is retained until the patency of the urinary tract is restored, the acute inflammatory process is eliminated and the kidney function is normalized.

Recently, internal drainage of the kidney has been increasingly used by installing a stent. Most urologists carry out drainage of the renal pelvis, both in primary and secondary apostematous nephritis. However, a number of urologists in the primary apostematous nephritis do not drain the kidney. Experience shows that the nephrostomy drainage established during the operation with a normal outflow of urine after the operation does not function. The discharge of urine is natural. With a bilateral, severe process, the kidney drainage is mandatory. In the postoperative period, antibacterial and detoxification therapy, correction of general disorders are carried out. After the acute inflammation subsides, the treatment of apostematous nephritis is carried out according to the scheme used for chronic pyelonephritis.

With total pustular kidney damage in elderly patients with severe intoxication, a good function of the opposite kidney is recommended immediately to produce nephrecomia. However, due to the fact that with the primary apostematous pyelonephritis, the possibility of affecting the second kidney is not excluded, the indications for nephrectomy should be sharply limited. An organ-saving operation with timely and correct execution of it, adequate post-operative treatment provides a satisfactory result.

Unfortunately, sometimes the operation is belated. It should be remembered that the intensification of antibiotic therapy without a combined effect on the local hearth does not give the expected result. In this case, early surgical treatment of apostematous nephritis should be recommended.

Prevention

Prophylaxis of apostematous nephritis is the timely diagnosis and treatment of pyelonephritis, the removal of obstacles that disrupt the outflow of urine from the upper urinary tract, and the sanation of foci of infection in the body.

[10], [11], [12]

Forecast

Two-sided apostematous pyelonephritis has an unfavorable prognosis, lethality reaches 15%. The possibility of developing late severe complications after organ-preserving operations (frequent exacerbations of chronic pyelonephritis, nephrogenic arterial hypertension, wrinkling of the operated kidney, formation of stones, etc.) dictates the necessity of lifelong active prophylactic medical examination of patients.