Diagnosis of acute pyelonephritis

The diagnosis of acute pyelonephritis is made in cases of the first occurrence of an infectious and inflammatory process in the renal pelvis and tubular-interstitial tissue of the kidneys, lasting 4-8 weeks, followed by favorable dynamics of clinical and laboratory symptoms and recovery no later than 3-6 months from the onset of the disease.

Chronic pyelonephritis is diagnosed when signs of the disease persist for more than 6 months from its onset or in the presence of 2-3 relapses during this period.

In the active stage, clinical symptoms and indicators of process activity are expressed, kidney function can be preserved or impaired. In case of kidney function impairment, the type and nature of impairment are indicated.

Complete clinical and laboratory remission is understood to mean the following changes:

1. disappearance of clinical symptoms;
2. normalization of urine sediment during routine examination and according to quantitative research methods;
3. return of blood parameters to age-related norms;
4. disappearance of pathological bacteriuria and isolation of pathogenic microbes from urine;
5. restoration of kidney function.

The period of partial remission is the absence of clinical symptoms or their weak expression, a significant reduction in shifts in urine sediment, the absence of pronounced functional disorders of the kidneys and changes in the blood.

Recovery can be considered if complete clinical and laboratory remission is maintained for at least three years. The patient must be comprehensively examined in a specialized nephrology hospital before the diagnosis is removed.

In outpatients, E. coli is predominant in the urine, and in cases of infection in a hospital setting, the etiological significance of Klebsiella, Pseudomonas aeruginosa, and Enterococcus increases.

Laboratory diagnostics of acute pyelonephritis.

1. Urine sediment: proteinuria less than 0.3-0.5 g/l; leukocyturia of neutrophilic nature.
2. Bacteriuria: the norm is 10 ⁵ (100,000) microbial bodies in 1 ml of urine taken by the usual method. TTX test, test with tetraphenyltetrazolium chloride.
3. Quantitative methods of urine analysis: the norm of the Kakovsky-Addis test (per day leukocytes - 2 million, erythrocytes - 1 million, cylinders - 10,000). Bacteriological method of determining bacteriuria using phase-contrast microscopy (method according to Stanfield-Webb). The norm is up to 3 leukocytes in 1 μl.
4. In girls, a urine sample from the middle portion and a smear from the vaginal discharge are tested simultaneously.
5. Urine culture for flora - repeated, at least 3 times.
6. Determination of titers of antibacterial antibodies in pyelonephritis (over 1:160).
7. Isolation of bacteria coated with antibodies in urine using immunofluorescence testing.
8. Dynamics of antibodies to lipid A.
9. DNA probe diagnostics is comparable to polymerase chain reaction (PCR).
10. Determination of P-lysine activity in urine.
11. Determination of IL-1 and IL-6 in urine.
12. Analysis of daily urine for salt content (norm: oxalates - 1 mg/kg/day, urates - 0.08-0.1 mmol/kg/day, or 0.6-6.0 mmol/day, phosphates -19-32 mmol/day).

Kidney function test.Functional methods of kidney examination in pyelonephritis may reveal the following abnormalities: Zimnitsky's test - decreased concentrating ability of the kidneys - hyposthenuria or isosthenuria. Impaired urine concentrating function indicates damage to the interstitial tissue of the kidney; impaired renal function in maintaining acid-base balance due to decreased ability to form ammonia and decreased excretion of hydrogen ions by renal tubular cells; impaired acido-ammoniogenesis reflects the function of the distal renal tubules; determination of beta ₂ -microglobulin content in urine. A significant increase is observed with predominant damage to the proximal renal tubules. The norm of beta ₂ -microglobulin in urine is from 135 to 174 μg/l. In patients with pyelonephritis, its level has been shown to increase by 3-5 or more times.

Ultrasound changes in pyelonephritis include: an increase in the volume of kidney lesions, expansion of the cups and pelvis, sometimes possible contouring of compacted papillae. If the bladder is involved in the process, signs of thickening of the mucous membrane are revealed, the shape of the bladder changes. There may be dilation of the distal ureter. In this case, it is necessary to conduct an instrumental examination to exclude vesicoureteral reflux. Cystography and micturition cystography are performed.

Radioisotope renographyreveals the unilaterality of the lesion, decreased secretory activity of the renal parenchyma, and slowing of the excretory function. In this case, the presence of fluctuations in the area of the excretory segment of the curve, the step-like nature of the excretion of the drug is an indirect sign of vesicorenal reflux. As it progresses, the vascular segment of the renogram decreases, the secretory phase slows down with a decrease in the degree of ascent of the curve, the excretory segment is sharply stretched in time, flattened.

X-ray contrast studyallows to reveal anomalies of the kidneys and urinary system, sclerosis of renal tissue. On the radiograph in acute non-obstructive pyelonephritis, smoothing of the contours of the papillae, spasm of the calyces, moderate deformation and expansion, their unequal size, blurring of the contours are revealed. Indirect radiographic signs of vesicoureteral reflux are partial unilateral or bilateral expansion of the distal ureter, filling of the ureter with a contrast agent along its entire length, often combined with total expansion of the ureter, renal pelvis and calyces.

Computed tomography reveals up to 85% of minimal structural damage to the renal parenchyma.

Endoscopic methods.Transurethral ureteropyeloscopy allows for more precise diagnostics of malformations of the upper urinary tract, the extent of segmental dysplasia of the ureter, and the determination of the valve or membrane of the ureter. Only this method allows for the diagnosis of small vascular tumors of the renal pelvis and calyces (hemangiomas, papillomas), which are often the cause of long-term microhematuria of unclear etiology.

Progress has been made in the field of prenatal diagnostics of kidney pathology. From the 15th week of the intrauterine period, ultrasound screening allows diagnosing congenital malformations of the kidneys (unilateral, bilateral anomalies, ureteral obstructions, polycystic kidney disease, severe renal dysplasia.

Classification of pyelonephritis in children

Form of pyelonephritis	Activity	Kidney function
1. Acute pyelonephritis	1. Active stage 2. Period of reverse development 3. Complete clinical and laboratory remission	Preservation of renal function. Impaired renal function.
2. Chronic pyelonephritis - primary non-obstructive - secondary obstructive A) recurrent B) latent course	1. Active stage 2. Partial clinical and laboratory remission 3. Complete clinical and laboratory remission	Preservation of kidney function Impaired renal function Chronic renal failure

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