Pyelonephritis is a nonspecific infectious and inflammatory process characterized by simultaneous or sequential damage to the calyx—pelvic system and the parenchyma (main tissue) of the kidney. Pyelonephritis can be both unilateral (one kidney is affected) and bilateral (both kidneys are affected).
The kidneys have two types of tissues: glomerular and tubulo-interstitial. The first carries out blood filtration and urine formation, the second – its collection and outflow from the kidneys to the ureters and bladder. Pyelonephritis is called inflammation of the tubulo-interstitial tissue responsible for collecting and removing urine into the ureters. The main cause of the uncomplicated disease is bacteria, such as E. coli, streptococci, staphylococci, proteus and others. Complicated pyelonephritis is caused by the same microorganisms, as well as Pseudomonas aeruginosa and fungi.
Primary pyelonephritis is isolated, associated with the penetration and reproduction of microorganisms, and secondary, caused by a violation of the outflow of urine.
The disease can occur in acute or chronic form with periodic exacerbations.
Primary acute pyelonephritis can manifest in practically healthy people after hypothermia or stressful situations. Acute obstructive pyelonephritis is usually caused by a violation of the outflow of urine, and a
cute non–obstructive – an ascending infection of the urinary tract. Chronic pyelonephritis can be the outcome of acute pyelonephritis, but more often occurs as a relatively calm process.
Each successive exacerbation of pyelonephritis is accompanied by the involvement of new sections of the functioning renal parenchyma in the inflammatory focal process. As a result of secondary inflammation, the surface of the kidney becomes uneven, large deep segmental scars form, the ureter expands. More often, the process is localized in the upper segment of the kidney.
The disease is common among all age groups, occurs in both adults and children. Chronic pyelonephritis is the most common kidney pathology, the incidence is 18 cases per 1000 people, acute pyelonephritis is 1 case per 1000 people. More often the disease is diagnosed in women, which is due to the anatomical structure of the urethra – it is wider and shorter than in men.