Obstructive uropathies are a group of diseases characterized by partial or total blockage of the flow of urine. Obstructions can be located at several parts within the urinary tract, extending from the kidneys to the urethra, and may be congenital or acquired, as well as either extra or intraluminal [1] . Without prompt diagnosis and management, these conditions progress toward end-stage renal disease. Recently, malformative uropathies have been more frequently identified during the prenatal stage, owing to advancements in fetal imaging technologies. Indeed, malformative uropathies represent the most prevalent causes of obstructive uropathies, with diverse etiologies [2] [3] . Congenital etiology is mainly posterior urethral valves (PUV) and ureteropelvic junction obstruction (UJPO). Although less common in pediatric populations, urolithiasis can also precipitate obstructions in urinary flow [4] - [6] . The retention of urine within the urinary tract and the disruption of normal urinary flow can lead to serious complications, including urinary tract infections, renal impairment, and urinary function abnormalities [7] . Due to diagnostic delays, these complications are frequently encountered in our clinical practice. Therefore, we conducted this study to describe the epidemiological and diagnostic features of obstructive uropathies in children as observed in our clinical practice.

This retrospective descriptive study was conducted over 6 years, from January 1, 2018, to December 31, 2023. It included all patients between 0 and 15 years old who were diagnosed with obstructive uropathy in the pediatric surgery department of Albert Royer Children’s Hospital in Dakar. Uropathy was suspected in case of urinary symptoms or urinary tract infection (UTI) and confirmed based on imaging. Patients whom the uropathy was not obstructive were not included. Data were collected from patients’ admission and hospitalization files and encoded on a preestablished questionnaire.

The study focused on the incidence of obstructive uropathies, the epidemiological characteristics of affected children, existence of antenatal diagnosis, circumstances of postnatal discovery, the imaging diagnostic criteria mainly urinary tract ultrasound, voiding cystourethrogram (VCUG) and urological CT-scan, associated malformations, and the types and anatomical locations of the various obstructive uropathies, the associated secondary complication on the upper urinary tract. Obtained data were encoded and analyzed using Word and Excel (Microsoft 2013).

We have documented 130 cases of obstructive uropathies, representing an average of 22 cases per year, with an in-hospital frequency of 0.43%. Uropathies are frequently encountered in pediatric surgery consultations. Nevertheless, obstructive uropathies are typically less common as shown in a Cameroonian study [3] . These conditions predominantly affect boys across all reported series [2] [3] . This is attributed to male-specific conditions such as PUV. Additionally, there is a notable predominance of cases in infants. Congenital anomalies of the kidneys and urinary tract (CAKUT) are the leading cause of obstructive uropathies, and those not detected during prenatal diagnosis often present as urinary infections between the ages of 1 and 24 months.

Prenatal ultrasound screening is highly effective in screening CAKUT, especially those that are obstructive [8] . However, it is not able to precisely highlight the obstruction site and does not always differentiate between upper and lower urinary tract issues. The exact mechanism causing the dilation is often unclear. In our study, only 27.67% of diagnoses were suspected prenatally; this rate remains low in Sub-Saharan Africa [3] , in contrast to European countries [9] .

The diagnosis delay and the prolonged symptom duration can be attributed to the clinical variability of diseases. Additionally, the occurrence of some complications postpones the conducting of some imaging tests required for etiological diagnosis. This situation is particularly applicable to VUCG, where repeated urinary tract infections frequently cause delays. In these infections, Escherichia coli is the most commonly encountered pathogen [10] .

Ultrasound examination of the urinary tract is crucial for investigating the urinary system, being the most straightforward and accessible technique even in a resource-limited context, that provides a detailed morphological evaluation of the kidneys and lower urinary tract. In our study, it was used in all our patients. Furthermore, when there is an antenatal diagnosis of obstructive CAKUT, a postnatal examination is necessary by the end of the first week to accurately diagnose malformations and obstructions, excepted for suspected PUV where postnatal urinary ultrasound screening is urgent [11] [12] .

The VUCG is a supplementary examination used for the morphological and functional assessment of the urethra and bladder. Its execution requires prior confirmation of the absence of urinary tract infection, and it should not be conducted as a first-line approach. Instead, it remains the reference imaging exam for diagnosing PUV. In children, the indications for urological CT scans are less frequent owing to its irradiating nature and the nephrotoxicity of the contrast product [13] . However, if a urological MRI is unavailable, CT scans are employed to diagnose obstructive urolithiasis and other upper urinary tract uropathies. This is the case in Sub-Saharan Africa where MRI is usually unavailable. Obstructive uropathies predominantly affect the upper urinary tract [14] . In our series, the upper urinary tract was the location of obstruction in 54% of cases. Additionally, the obstruction site was most often on the left side, as also noted in the literature, whether for obstructive CAKUT or urolithiasis [15] .

In our study, PUV was the most common obstructive uropathy, accounting for 39% of cases. Likewise, in other African studies, PUV is identified as the leading cause of lower urinary tract obstruction [3] [16] . In contrast, other research has shown that UPJO is more prevalent, with PUV being the second most common [2] [15] . This discrepancy is likely due to the limited availability of endoscopic resectoscopes for PUV in many medical facilities, leading to the referral of numerous affected newborns to our institution. Other potential causes of urinary tract obstruction, such as ureterocele and ectopic ureter in a ureteral duplex anomaly, are generally regarded as less common [9] [17] [18] .

The correlation between obstructive uropathies and other genitourinary malformations is well-documented in the literature [19] - [22] . In our series, 18% of the patients exhibited such associations, with cryptorchidism being the most frequently accompanying malformation with obstructive uropathies.

The main limitation is the retrospective nature of the study, which induced some missing data. The lack of some early investigations has influenced the patient’s diagnostic profile.

Obstructive uropathies are frequently encountered, predominantly due to malformations, and are most commonly diagnosed in infants in our clinical experience. Ultrasound screening of the urinary tract should continue to be the first-line investigation to guide subsequent imaging studies. The etiologies predominantly involve posterior urethral valves, ureteropelvic junction obstruction, and obstructive urolithiasis.