Hydronephrosis associated with abnormalities of the pelvic-ureteral junction: clinic and diagnosis.

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Introduction
Hydronephrosis is a pathological condition characterized by the progressive dilation of the renal calyceal-pelvic system due to impaired urine outflow, leading to parenchymal atrophy and a decrease in kidney function. The primary causes of hydronephrosis include urinary tract obstructions caused by stones, strictures, tumors, retroperitoneal fibrosis, and other conditions. If not treated in time, hydronephrosis can lead to chronic kidney failure [1].

The widespread use of prenatal ultrasonography (US) has enabled earlier and more frequent detection of urinary system anomalies than before. The incidence of pelviureteric junction (PUJ) type hydronephrosis is estimated to be between 1 in 750–2000 cases, making it the most common cause of hydronephrosis in children. This pathology is found in 13% of children with prenatally diagnosed renal pelvis dilation, more often affecting the left kidney and occurring predominantly in boys (with a ratio of 2:1), whereas bilateral involvement is significantly less common.

Anomalies of the pelviureteric junction (PUJ) are congenital or acquired changes that disrupt normal urine outflow. These include obstruction, compression by abnormal vessels, fibrotic strictures, and dysplasia. These conditions can lead to hydronephrosis and reduced kidney function [2].

Obstruction at the pelviureteric junction, which involves impaired urine passage from the renal pelvis into the ureter, can lead to progressive kidney tissue dysfunction or hinder its normal development. More than 50% of all congenital kidney anomalies detected prenatally are cases of hydronephrosis. However, reliable prenatal diagnostic methods to differentiate between obstructive and non-obstructive hydronephrosis are currently lacking. Differentiation of these forms and determining the degree of urinary tract obstruction are key aspects of patient management.

According to the World Health Organization (WHO), congenital malformations of the urinary system are one of the leading causes of chronic kidney disease in children. WHO emphasizes the importance of early diagnosis and a multidisciplinary approach to treating these conditions, including the use of modern imaging methods, kidney function monitoring, and timely surgical correction in cases of significant obstruction.

Given the variability in clinical manifestations and the complexity of generalizing the disease course, the optimal approach for managing children with (N13.0) is an individualized assessment of each clinical case. This article aims to compile and present information on the clinical presentation and symptoms of hydronephrosis caused by pelviureteric junction pathologies, as well as analyze clinical data based on case studies.

The objective of this study is to gather and analyze scientific research on the clinical presentation and symptoms of hydronephrosis caused by pelviureteric junction pathologies, along with the examination of clinical data based on case examples.

Materials and Methods

The study involves the search and analysis of contemporary publications on this topic.

Research Results

The pathogenesis of hydronephrosis associated with pelviureteric junction anomalies (N13.0) is due to impaired normal urine drainage from the kidney into the ureter, leading to an enlarged renal pelvis, subsequent dilation of the collecting duct system, and atrophy of kidney tissue. This disruption may be caused by both mechanical and functional obstruction at the pelviureteric junction [3]. The key mechanisms of pathogenesis include:

Obstruction at the pelviureteric junction. This can be caused by various anatomical anomalies such as improper arrangement of muscle layers, hypoplasia of muscle tissue, the presence of an accessory blood vessel compressing the junction, or fibrotic changes [4].

Impaired normal ureteral peristalsis. PUJ anomalies can disrupt adequate peristalsis of the ureter, leading to decreased or absent urine evacuation from the kidney [4].

Increased intrarenal pressure. Urine stasis in the kidney leads to increased hydrostatic pressure in the renal pelvis, which gradually stretches the entire renal system, including the tubules and interstitial tissue [4].

Renal tissue dystrophy. Chronic pressure increase and tissue stretching result in atrophy of the renal tubules and interstitial tissue [4].

Decline in kidney function. As the disease progresses, normal kidney function deteriorates due to damage to the renal tubules and glomeruli. Notably, functional changes do not always correspond to the size of hydronephrosis, making diagnosis and decision-making about interventions challenging [4].

Thus, it is essential to consider the key clinical manifestations that play an important role in diagnosing this condition.

Hydronephrosis associated with pelviureteric junction anomalies (N13.0) can present with various clinical pictures, depending on the degree of obstruction and whether one or both kidneys are affected. In recent decades, there has been a trend toward diagnosing this pathology in asymptomatic newborns due to prenatal ultrasound screening, significantly altering the traditional understanding of the disease. In such patients, hydronephrosis often remains asymptomatic and does not require intervention, leading to a more conservative treatment approach focused on observation [4].

If prenatal diagnosis is absent, patients may exhibit symptoms such as fever, urinary tract infections (UTIs), abdominal masses, pain, pyuria, hematuria, or even gastrointestinal symptoms in the postnatal period. Less common manifestations include developmental delay, anemia, hypertension, and urinary extravasation. Severe forms of hydronephrosis, despite significant kidney enlargement, may not cause pronounced symptoms and often remain undetected until a later age when more severe kidney function impairment may occur [5].

The clinical course of the disease depends on the degree and location of the obstruction, as well as whether one or both kidneys are affected. In severe cases of hydronephrosis (e.g., Grade IV), where renal parenchymal thinning and significant loss of kidney function are present, surgical intervention is required. It is crucial to consider that even in the absence of symptoms, serious structural changes in the kidney, such as parenchymal thinning, compensatory hypertrophy of the contralateral kidney, and declining kidney function, are indications for surgery. Since late detection of hydronephrosis can lead to irreversible consequences, it is vital to recognize its symptoms early for accurate diagnosis and timely treatment.

In the prenatal period, hydronephrosis in children is typically asymptomatic, as it is most often detected incidentally during routine ultrasound examinations. However, signs of hydronephrosis may be visible on ultrasound screening, where dilation of the renal pelvis and other urinary structures is observed, characteristic of this condition [6].

The modern treatment approach includes conservative methods with regular patient monitoring, including ultrasound examinations and clinical assessments. Worsening ultrasound or functional kidney parameters serve as grounds for surgical intervention, especially in cases where there is a risk of further kidney damage or complications such as urosepsis or acute kidney failure. Importantly, in cases of recurrent UTIs, hematuria, kidney stones, or pain, a surgical decision should be made without delay [6].

Failure to treat hydronephrosis associated with pelviureteric junction anomalies may lead to chronic kidney disease due to kidney tissue atrophy and decreased functional activity. Urine retention promotes the development of urosepsis, which can lead to kidney and systemic infections. Impaired kidney function may cause arterial hypertension, and in later stages, progressive renal failure requiring replacement therapy (dialysis). Without timely treatment, kidney hypoplasia and underdevelopment may occur. Chronic kidney inflammation leads to hematuria, pyuria, and recurrent urinary tract infections, worsening the patient’s condition. Therefore, early diagnosis and timely intervention are crucial to prevent these complications [6].

Thus, the clinical presentation of (N13.0) includes both asymptomatic forms detected through prenatal screening and symptoms developing later in life, with potential complications requiring surgical intervention.

Conclusion

Hydronephrosis caused by pelviureteric junction anomalies is a serious pathology that can lead to progressive kidney dysfunction, chronic kidney disease, urosepsis, hypertension, and other complications. Early diagnosis, particularly through prenatal ultrasonography, is a crucial factor in detecting the condition at an early stage. Without timely treatment, the disease may cause irreversible kidney damage, necessitating surgical intervention. Regular patient monitoring and timely surgical treatment are key to preventing severe consequences and preserving kidney function.

About the authors

Ilia Vladimirovich Gusev

Author for correspondence.
Email: ilagusev67882@mail.ru
ORCID iD: 0009-0002-1271-2198
Russian Federation, 10 Studencheskaya str., Voronezh, 394036, Russia

Anna Alexandrovna Voronova

Email: voronova_anna1505@mail.ru
ORCID iD: 0009-0009-7155-8590
10 Studencheskaya str., Voronezh, 394036, Russia

References

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