Apostematous pyelonephritis is an acute purulent–inflammatory disease characterized by the formation of multiple abscesses in the parenchyma (medulla) of one or both kidneys. Symptoms are a sharp increase in temperature, chills, pain in the lumbar region, manifestations of general intoxication (headache, nausea, vomiting), rigidity of the abdominal muscles. Diagnosis is made on the basis of a general urine analysis, bacteriological examination of urinary sediment, ultrasound, radiography, magnetic resonance imaging of the kidneys. Treatment is reduced to emergency surgical intervention to eliminate purulent foci and drainage, with severe forms, nephrectomy is indicated.
ICD 10
N12 Tubulointerstitial nephritis, not specified as acute or chronic
Meaning
Apostematous pyelonephritis is usually considered as one of the severe forms of acute purulent pyelonephritis. Some authors consider it a complication of this disease. There is a relationship of pathology with another form of purulent-inflammatory lesion of the excretory organs – kidney carbuncle. There is an opinion that the conditions “purulent pyelonephritis – apostematous inflammation – carbuncle – kidney abscess” are successive stages of the same pathological process. The exact prevalence is unknown, it is assumed that the disease occurs in 5-12% of cases of acute pyelonephritis. With delayed diagnosis and late initiation of treatment, the risk of developing pathology increases. In childhood, young and mature age, women suffer several times more often than men, in the age group over 60 years, the picture of morbidity is leveled.
Causes
The main cause of the development of apostematous inflammation is infection of the renal pelvis with virulent bacteria, followed by multi-stage penetration of microorganisms first into the tubules, and then into the parenchyma of the kidneys. The source of infection can be both in the patient’s body (abscesses and inflammation in other organs) and beyond. There is an ascending path of infection (from the external environment through the urinary tract) and a descending one – with the flow of lymph or blood from other foci. There are a number of factors predisposing to the development of apostematous pyelonephritis:
- The presence of foci of infection. Inflammatory and purulent-inflammatory processes in various organs can serve as a source of infection, which, penetrating into the kidneys in a hematogenic or lymphogenic way, leads to the development of pathology. Cases of the occurrence of the disease during the spread of the process from carious teeth, foci in the gastrointestinal tract, bladder are described.
- Urodynamic disorders. Stagnation or reflux of urine in the tubules, cup-pelvic system, ureters creates conditions for the accumulation of microorganisms and their penetration into the kidney tissue. The cause of violations of the dynamics of urine can be urolithiasis, ureteral spasm, bladder dyskinesia, in men – prostatic hypertrophy.
- Anatomical features. Due to certain features of the anatomical structure of the genitourinary system, purulent pyelonephritis occurs more often in women. The urinary tract (in particular, the urethra) is wider and shorter, which facilitates the penetration of an ascending infection.
- Immunological features. It has been established that an important role in the pathogenesis of apostematous pyelonephritis is played by a delayed immune reaction that develops only when the pathogen hits the surface of the epithelium of convoluted tubules. Perhaps this is due to genetic characteristics of reactivity or acquired and transient factors affecting the activity of immunity.
If we consider this condition as a complication of secondary purulent pyelonephritis, then its causes include delayed or incorrect treatment of the underlying disease. Among other factors affecting the development of pathology, sometimes there are congenital features of the blood supply to the kidneys and the structure of the tubules, the nature and virulence of bacterial infection.
Pathogenesis
With apostematous pyelonephritis, the hematogenic pathway of penetration of bacteria into the tissues of the excretory organs prevails. The repetitive nature of bacteremia is important – a single entry of the pathogen into the glomeruli does not lead to infection, but damages the walls of the capillaries. In subsequent episodes of bacteremia, microorganisms can penetrate through the wall and get into the lumen of the nephron capsule and convoluted tubules of the first order. At this stage, the state of urodynamics is of great importance – with a normal outflow of primary urine, bacteria are excreted with it and do not have time to cause inflammation. With stagnation, there is a rapid multiplication of pathogens in the lumen of the tubules, which increases the risk of an apostematous purulent process.
Bacteria begin to penetrate the walls of the tubules, severely damaging the tubular epithelium. Only at this stage an immunological reaction occurs, consisting in a strong leukocyte infiltration of the affected nephrons with the death of epithelial cells and numerous ruptures of the basement membrane. Pathogens enter the interstitial tissue, which leads to the formation of numerous peritubular purulent infiltrates, poorly delimited by the inflammatory shaft. There is a strong intoxication of the body with products of purulent inflammation.
As the pathology proceeds, the pustules may merge with each other, forming a carbuncle or abscess. Sometimes the inflammatory shaft is organized around them, there is a proliferation of connective tissue until the complete disappearance of inflammation. The outcome of uncomplicated apostematous pyelonephritis is the formation of sclerosis sites at the site of purulent infiltrates. It is possible for ulcers to break through the kidney membrane with the involvement of the peritoneum and surrounding tissues in the pathological process.
Classification
There are two ways to classify apostematous pyelonephritis – according to the etiological nature of the lesion and its spread to one or both kidneys. Each type is characterized by certain features of the causes of development, clinical manifestations, treatment approaches and prognosis. Taking into account the ethology of the disease , there are two main groups:
- Primary defeat. This group includes cases of the disease that have developed against the background of previously unaffected, completely healthy excretory organs. The infection penetrates lymphogenically or hematogenically from distant inflammatory foci. The condition for the development of the disease is the high virulence of the pathogen and the reduced activity of the immune system.
- Secondary lesion. This more common type includes episodes of pathology that are diagnosed against the background of kidney disease or other organs of the urinary system – urolithiasis, cystitis, dyskinesia of the bladder. Urodynamic disorders play an important role in the occurrence of a pathological condition.
According to the prevalence of the lesion, unilateral and bilateral forms of apostematous inflammation of the kidneys are distinguished. The reason for the involvement of both organs in the process at once is frequent massive bacteremia, this form is caused by hematogenous penetration of infection and often has a primary character. The more common (in 95% of cases of the disease) unilateral lesion is more often secondary, due to disorders of urodynamics in a particular kidney. A decrease in the activity of the immune system increases the likelihood of developing all forms of the disease.
Symptoms
There is a certain difference in the clinical manifestations of primary and secondary forms of pathology. The hematogenic primary type of the disease always begins acutely, with dull pain in the lower back, chills, fever up to 39-40 degrees and above. From the first hours, signs of severe intoxication of the body are registered: headaches, decreased appetite, vomiting. In severe cases, there is a decrease in blood pressure, tachycardia, confusion. Lower back pain increases sharply on the 5th–6th day of the disease – this indicates the involvement of the renal capsule in the process with its possible breakthrough.
The onset of the disease with secondary apostematous pyelonephritis is rarely sudden – it is usually preceded by a period of renal colic lasting from several hours to 2-3 days. Sometimes there is a development of the disease after interventions on the organs of the excretory system. Another significant difference is the nature of the lesion – with primary inflammation it is more often bilateral, with secondary – unilateral. This is reflected in pain in the lower back – with the secondary type, patients first complain of a shingling dull pain, but on day 4-5 it is intensified by the lesion.
In the future (4-6 days after the onset of the disease), the nature of the course of pathology is approximately the same in all forms. There is rigidity of the abdominal muscles, which indicates the involvement of the peritoneum. The kidneys become a source of a purulent infection – with the blood flow and through the lymphatic pathways, it can spread to the lungs, brain, liver. This leads to the development of pneumonia, purulent pleurisy, liver and brain abscesses. Acute renal failure (acute renal failure) occurs, characterized first by a complete absence of urine (anuria), and then by a sharp increase in diuresis (polyuria). With liver damage, jaundice, symptoms of acute liver failure are observed.
Complications
ARF often develops even with unilateral apostematous pyelonephritis due to toxic-septic damage to the second kidney. Among other common complications are the formation of abscesses and the occurrence of purulent-inflammatory processes in the pleura, lungs, liver due to the introduction of infection with blood or through the lymphatic pathways. The most severe complication is considered to be urosepsis. The long-term consequences of pathology are fibrosis and wrinkling of the kidney, which can cause disruption of the juxtaglomerular apparatus. The consequence of this is erythropoiesis disorders (hypoplastic anemia, polycythemia), persistent increase in blood pressure.
Diagnostics
The acute nature of apostematous pyelonephritis, its rapid development and the high risk of serious complications necessitate a quick and correct diagnosis. The urologist is responsible for determining the presence of pathology. Diagnostics includes an extensive list of instrumental and laboratory tests, consists of the following stages:
- Physical examination and interview. The doctor analyzes the patient’s complaints, collects anamnesis of the disease, clarifies whether the patient suffered from diseases of the excretory system, which symptoms occurred first (pain or fever). Palpation reveals soreness on the part of the affected organ, sometimes it is possible to determine an increase in the kidney.
- Laboratory tests. In the first few days, changes are rarely observed in the general analysis of urine. Then microhematuria is detected, the appearance of protein (proteinuria), pronounced leukocyturia, bacteria are detected by microscopy of the sediment. The results of the general blood test correspond to those of acute inflammation – a sharp increase in ESR, neutrophilia with a strong shift to the left, the BAC confirms hypoproteinemia.
- Ultrasound research methods. Ultrasound of the kidneys determines an increase in one or both organs, swelling of the surrounding fiber, decreased mobility with forced breathing. After a few days, hyperechogenicity of the parenchyma is noted, in the thickness of which there are many small (1-3 mm) hypoechoic formations.
- Kidney CT. The study allows you to identify the localization and size of the aposema, exclude or confirm an abscess or carbuncle of the kidney.
Treatment
In modern urology, surgical methods of treating the disease are used. The remaining techniques play an auxiliary role, their use without surgery is justified only in weakened patients who are contraindicated surgery. Postoperative therapy is important, aimed at maintaining vital functions, reducing intoxication phenomena, restoring the excretory system. The algorithm for the treatment of apostematous pyelonephritis is as follows:
- Surgical intervention. In most cases, it consists in decapsulation of the kidney, drainage of ulcers and retroperitoneal tissue, the formation of temporary pathways for the outflow of urine through pyelostomy. With unilateral lesions in older patients, nephrectomy is indicated.
- Antibiotic therapy. Broad-spectrum antibacterial agents are prescribed immediately after clarifying the diagnosis, after determining the nature of the pathogen and its sensitivity to drugs, it is possible to switch to other antibiotics. Medication is continued during the recovery period after surgery.
- Detoxification. Before and after surgery, the patient is prescribed infusion therapy, taking into account the filtration capacity of the kidneys. The patient is injected with enzymes, vitamins, blood plasma, diuretics and other drugs.
- Hemodialysis. The need for hemodialysis occurs in acute renal failure, the frequency of its implementation depends on the urological indicators of the patient.
The duration of antibacterial treatment, infusion therapy and hemodialysis is determined individually, taking into account the patient’s condition. The decision on the necessity and duration of the functioning of a pyelostomy or nephropyelostomy is made by the surgeon – often with a unilateral lesion, its creation is abandoned, preserving the natural pathways of urine outflow. After surgery, constant monitoring of kidney function is necessary – determination of creatinine level, daily diuresis and other indicators.
Prognosis and prevention
The mortality rate in apostematous pyelonephritis is quite high, in some cases reaches 10%. The prognosis for life improves with timely access to a doctor and early initiation of treatment. Special care should be taken by persons with chronic kidney diseases (pyelonephritis, urolithiasis) – if there are any signs of an exacerbation of the process, you should urgently contact a specialist. Prevention of the condition consists in the timely elimination of inflammatory foci in the body (including those of a neurological nature). It is necessary to avoid hypothermia of the lumbar region, observe the rules of hygiene of the external genitalia, carry out full-fledged treatment of diseases of the urinary system.
