What causes vesicoureteral reflux?

The causes and pathogenesis of vesicoureteral reflux have been studied for more than 100 years, but to date they have not become more understandable for a significant number of clinicians and morphologists. Existing points of view on the causes of the onset and the mechanism of the development of vesicoureteral reflux are sometimes so contradictory that even now this problem can not be considered solved to the end.

Bladder and ureter reflux with the same frequency occurs in boys and girls. However, at the age of up to one year, the disease is predominantly diagnosed in boys in a 6: 1 ratio, whereas after 3 years with the greatest frequency, it is diagnosed in girls.

The following variants of development of vesicoureteral reflux are considered:

• the appearance of reflux on the background of congenital underdevelopment of OMS without infection of the urinary system;
• the appearance of reflux on the background of congenital underdevelopment of OMS in the development of infection of the urinary system;
• the appearance of reflux due to genetically determined defects in the structure of CHI.

At the heart of the development of vesicoureteral reflux is the violation of the processes of combining metanephrogenic tissue with metanephrogenic blastema and metanephrogenic diverticulum with the wall of the bladder. A direct correlation between the degree of vesicoureteral reflux and ectopic ureteral opening was revealed. There is a large number of theories explaining the inconsistency of the antireflux mechanism. However, the main cause of vesicoureteral reflux is currently considered dysplasia of the uretero-vesicle segment.

Congenital malformations of the structure of ultrasound are mainly muscle hypoplasia with the replacement of coarse collagen fibers in the wall of the distal ureter, varying degrees of severity and prevalence. Underdevelopment of the neuromuscular system and the elastic framework of the ureter wall, low contractility, disruption of the interaction between the peristalsis of the ureter and contractions of the bladder can contribute to the onset and progression of vesicoureteral reflux.

In the literature, families are described in which reflux of various degrees of severity has occurred in several generations. There is a hypothesis about the existence of an autosomal dominant type of inheritance with incomplete pententrantity of the gene or a multifactorial type of inheritance.

Primary is considered vesicoureteral reflux, which arose because of congenital insufficiency or immaturity of the vesicoureteral segment. This is confirmed by the high incidence of vesicoureteral reflux in children compared with adults. The younger the child, the more often he has vesicoureteral reflux. With age, there is a tendency to decrease the incidence of vesicoureteral reflux. In this case, the regression frequency is inversely related to the degree of vesicoureteral reflux. At 1-2 degrees of vesicoureteral reflux, regression is noted in 80% of cases, and at 3-4 degrees in only 40%.

In cases where reflux is a consequence of other diseases OMS (neurogenic dysfunction of the bladder, cystitis, etc.), it is regarded as a toric. Until recently, many urologists considered the main cause of the development of vesicoureteral reflux infravesical obstruction, which is recorded in 90-92% of cases in this pathology.

In girls, one of the most common causes of secondary vesicoureteral reflux is chronic cystitis. Reversible changes in the uretero-vesicular segment of inflammatory origin usually cause the transient nature of Peflusx. However, as the duration of the disease increases, the intensity of the inflammatory process increases. It spreads over a longer distance and captures deeper structures of the bladder, which leads to a violation of the antireflux mechanism. The subsequent progression of the chronic inflammatory process leads to sclerotic changes in the intramural ureter and atrophy of the muscular membrane, which causes rigidity, and in some cases, retraction of the blocking epithelial plate of the ureteral orifices. As a result, the ureteral orifices start to glow, and their edges cease to close.

Constipation contributes to the compression of the lower third of the ureter and bladder, impaired vascularization, stagnation in the pelvic region, lymphogenous infection of the bladder, the occurrence of cystitis, in addition, frequent false urges to defecate lead to an increase in the pressure of the abdominal cavity, inducing unrestrained pressure fluctuations in the bladder, to provocation and exacerbation of pyelonephritis.

Peculiarities of the pathogenesis of vesicoureteral reflux in children of early age. The urgency of the problem of vesicoureteral reflux in children of early age is determined by its greatest frequency in this group of patients due to the relative morpho-functional immaturity or the developmental defect of the vesicoureteral segment. Arising at an early age, the reflux promotes the development of ureterohydronephrosis, cicatricial changes and kidney lag in growth, the emergence of reflux-nephropathy, chronic pyelonephritis, chronic renal failure, which leads to disability of patients both in childhood and in adulthood.

Often it is very difficult to determine the cause of vesicoureteral reflux in children of an early age, and even a pathomorphological study can not answer the question "congenital or acquired pathology". All this may be due to the effect of inflammation on the relatively immature morpho-functional structures of the vesicoureteral segment of the child.

Most often, the causes leading to the development of vesicoureteral reflux are congenital. That is why reflux is more common at an early age. The most common cause of vesicoureteral reflux in children of early age may be morpho-functional immaturity of the upper and lower urinary tract of the vesicoureteral segment, pelvic organs, which, with the combined effect of many pathological factors, contributes to the decompensation of the vesicoureteral segment, the onset of vesicoureteral reflux and its complications,

Age and function of valves are the most important factors in the pathogenesis of reflux. This is confirmed by the existence of a "reflux-surprise" in newborns and infants. Currently, reflux is considered a pathology at any age. However, sometimes at an early age with vesicoureteral reflux 1 and 2 degrees can be a spontaneous disappearance. Nevertheless, recent research indicates that even with low degrees of reflux, even without infection, nephrosclerosis may develop. Therefore, the problem of vesicoureteral reflux should be taken very seriously, and children are shown a long follow-up observation.

Classification of vesicoureteral reflux

Classification of vesicoureteral reflux has been repeatedly subjected to changes and additions. Currently, the classification recommended by the International Committee for the Study of Vesicoureteral Reflux in Children is recommended.

According to this classification, primary and secondary vesicoureteral reflux are isolated. By primary vesicoureteral reflux is an isolated developmental anomaly characterized by the presence of various types of vesicoureteral dysplasia. When combined vesicoureteral reflux with other abnormalities of the development of the urinary tract, which cause the development of dysfunction of the vesicoureteral anastomosis, it is customary to speak of secondary vesicoureteral reflux.

Also, the gradation of vesicoureteral reflux is distinguished depending on the degree of casting of the X-ray contrast medium and the dilatation of the cavity system during the carrying out of the microscopic cystography:

• 1 degree - reverse throw urine from the bladder only in the distal ureter without its expansion;
• 2 degree - casting into the ureter, pelvis and calyx, without dilatation and changes from the forties;
• 3 degree - slight or moderate dilatation of the ureter and pelvis in the absence or tendency to form a right angle by the forearms;
• 4 degree - pronounced dilatation of the ureter, its tortuosity, dilatation of the pelvis and calyxes, coarseness of the acute angle of the forearms, while maintaining papillarity in most cups;
• 5 degree - dilatation and sinuosity of the ureter, pronounced dilatation of the pelvis and calyxes; in most calyxes, papillary is not traced.

In this case, 4 and 5 degrees of vesicoureteral reflux are hydronephrosis transformation.

Classification of vesicoureteral reflux

A type	Cause
Primary	Congenital failure of the valve mechanism of the ureteral-vesicular junction
Primary, associated with other anomalies of the ureterocavit articulation	Duplication of the ureter. Ureterocele with doubling. Ectopic ureter Periurethral diverticula
Secondary, associated with increased pressure in the bladder	Neurogenic bladder Obstruction of the exit tract of the bladder
Secondary due to inflammatory changes	Clinically pronounced cystitis. Severe bacterial cystitis. Foreign bodies. Stones in the bladder.
Secondary due to surgical manipulations in the area of ureterovascular-articular articulation

This classification is extremely important for determining the further tactics of managing patients, solving the problem of surgical treatment.