Ureterovesical Junction Obstruction

Abstract

Ureterovesical junction obstruction (UVJO) represents a clinical and surgical dilemma for pediatric urologists. With the widespread use of obstetric ultrasonography, the prenatal detection of urinary tract dilatations has progressively increased and is reported in approximately 1-5% of all pregnancies (Nguyen et al., J Pediat Urol 6: 212-231, 2010). Currently, UVJO accounts for 5-10% of all clinically significant uropathies antenatally detected, (Lopez et al., J Laparoendoscop Adv Surg Tech, 2020; Braga et al., J Urol 195(4 Part 2):1300-1305, 2016) while approximately 20-25% of children with a diagnosis of suspected UVJO will, eventually, require a surgical intervention (Lopez et al., J Laparoendoscop Adv Surg Tech, 2020; Dekirmendjian and Braga Front Pediatr 7:126, 2019; Di Renzo et al., J Urol 190(3): 1021-1027, 2013). Since the majority of perinatally detected nephro-ureteric dilatation resolves spontaneously, a closed monitoring of these babies is essential to identify those who require a surgical intervention in order to prevent possible complications such as recurrent urinary tract infections (UTIs) and renal damage (Lopez et al., J Laparoendoscop Adv Surg Tech, 2020; Dekirmendjian and Braga, Front Pediatr 7:126, 2019; Di Renzo et al., J Urol 190(3): 1021-1027, 2013). The holdup of the urine caused by the obstruction, in fact, can predispose to overgrowth of opportunistic uropathogens while the chronically increased hydrostatic pressure can induce renal cell injury, loss of peritubular capillaries, and fibrosis, leading to long-term renal impairment (Truong et al., Obstructive uropathy. In: Herrera GA, ed. Contributions to nephrology, vol 169. S. Karger AG, 311-326, 2011). In most cases, however, there is a delayed drainage rather than a significant obstruction making difficult to predict whether the affected kidney is a risk of damage; in such cases, the indication for surgery is generally formulated after repeated tests and is based on evidence of renal function deterioration or presence of symptoms (Di Renzo et al., J Urol 190 1021-1027, 2013; Farrugia et al., J Pediatr Urol 10(1):26-33, 2014; Merlini and Spina, J Pediat Urol 1(6):409-417, 2005). Worsening of hydroureteronephrosis on repeated ultrasound scans, dropping of ipsilateral renal function on radioisotope investigations, and recurrent UTIs are, currently, the main criteria adopted for posing the indication for a surgical intervention (Di Renzo et al., J Urol 190 1021-1027, 2013; Farrugia et al., J Pediatr Urol 10(1):26-33, 2014; Merlini and Spina, J Pediat Urol 1(6):409-417, 2005). Regarding surgical management, open ureteral reimplantation, historically considered the gold standard, has been more recently replaced by a wide range of minimally invasive approaches, including endourological. In particular, laparoscopic and robotic ureteral reimplantation, having the advantages of minimal invasiveness, have progressively gained popularity as reconstructive procedure of choice (Lopez et al., J Laparoendoscop Adv Surg Tech, 2020). Endoscopic techniques, such as temporary insertion of double J stent, endoscopic highpressure balloon dilatation (HPBD) and cutting balloon endoureterotomy (CBU) have been increasingly adopted and demonstrated successful in providing excellent outcomes with few complications to the point that they are now considered the primary approach for UVJO in many centers (Parente and Esposito, Front Pediatr 7:365, 2019).