Introduction

The etiology of ureteropelvic junction obstruction may result from a number of factors, and can be classified as congenital or acquired in origin. Congenital ureteropelvic junction obstruction is typically characterized by an intrinsic luminal narrowing that is caused by an aperistaltic segment, in which the spiral musculature has been replaced by abnormal longitudinal muscle fibers and fibrous tissue (1-2). A less frequent cause of congenital ureteropelvic junction obstruction is a proximal ureteral stricture caused by abnormal ureteral muscle fiber and collagen deposition in this area (3). Additionally, intrinsic obstruction can be caused by infoldings of ureteral mucosa, a phenomenon that may result from exaggeration of congenital folds that are normally found in the ureter during fetal development (4). In some instances, ureteral adventitia may be present as external bands or adhesions that cause obstruction by producing angulation of the proximal ureter at the lower margin of the renal pelvis. High insertion of the ureter has also been reported as a primary obstructing lesion, and may coincide with other renal anomalies such as ectopia or abnormal fusion (5).

Acquired ureteropelvic junction obstruction may be the result of long-standing vesicoureteral reflux that leads to dilatation of the renal pelvis and upper ureter, with subsequent development of elongation, tortuosity, and kinking. Other causes of obstruction include fibroepi-thelial polyps, urothelial tumors, urolithiasis, and inflammation or scarring caused by prior surgery or ischemia.

The role of aberrant crossing vessels in the etiology of ureteropelvic junction obstruction remains controversial. Arteries or veins supplying the lower renal pole are noted if as many as 79% of patients with symptomatic ureteropelvic junction obstruction (6), and may arise from the main renal artery or vein, or directly from the great vessels. These vessels usually cross the ureteropelvic junction anteriorly; however in a minority of patients, these vessels cross posteriorly. As crossing vessels have been documented in patients with a normal ureteropelvic junction, it is possible that the associated vessel alone may not be solely responsible as the primary cause of the obstruction.

Technologic advances have played a significant role in the therapeutic management of ureteropelvic junction obstruction and have enabled the introduction of laparoscopic- and robotic-assisted laparoscopic pyeloplasty over the last several years.

The robot offers the potential advantages of enhanced three-dimensional visualization, improved dexterity, greater precision, increased range of motion, and reproducibility to even the smallest children. Despite reports of laparoscopic procedures being performed in various pediatric urologic procedures, only a handful of centers have embraced this technology.

The surgical robot is ideally suited for the reconstruction of the ureteropelvic junction and is a good procedure for the novice robotic surgeon to attempt.

Open pyeloplasty has been the standard treatment for congenital or acquired ureteropelvic junction in adults and children, with overall success rates of 90% to 100%.

A combination of an intrinsic lesion at the ureteropelvic junction and subsequent dilatation and draping of the renal pelvis over the polar vessels may be more likely Nevertheless, the incidence of crossing vessels in the symptomatic population is higher and appears to have functional significance.

Open pyeloplasty has been the standard treatment for congenital or acquired ureteropelvic junction in adults and children, with overall success rates of 90% to 100% (7-9).

The desire to decrease surgical morbidity associated with open surgery has led to the evolution of less invasive procedures over the past two decades, including percutaneous antegrade and ureteroscopic retrograde endopyelotomy. Despite lower success rates of 61% to 89% and an increased risk for perioperative hemorrhage (10-15), the endoscopic approaches have gained favor over open pyeloplasty.

Technologic advances have played a significant role in the therapeutic management of ureteropelvic junction obstruction and have enabled the introduction of laparoscopic- and robotic-assisted laparoscopic pyeloplasty over the last several years.

Laparoscopic pyeloplasty was first described in 1993 by Schuessler et al. (16). This procedure maintained the benefits of endoscopic approaches, short length of hospitali-zation, and reduced postoperative recovery time, while demonstrating comparable success rates to the conventional open approach (17-20). However, the technical challenge of reconstruction limited this procedure to select medical centers with advanced laparoscopic surgeons.

The introduction of robotic-assisted laparoscopic surgery has widened the surgical dimensions for minimally invasive surgery. Specifically, the availability of the da VinciĀ® Robota has facilitated complex reconstructive and laparoscopic procedures (21-23). The benefits imparted to the surgeon include enhanced three-dimensional visualization, improved dexterity, greater precision, increased range of motion, and reproducibility. The robot offers these potential advantages to even the smallest children. Despite reports of laparoscopic procedures being performed in various pediatric urologic procedures, only a handful of centers have embraced this technology.

This may be secondary to practice patterns but more likely reflects the inability of most practitioners to successfully implement and exploit laparoscopy for complex reconstructive procedures. With the advent of surgical robotics, the potential for a larger group of surgeons to employ minimal invasive methods for pediatric urologic operations is possible.

Over the last 10 years, laparoscopic pyeloplasties have been performed in adults and children but still remain a challenge for most surgeons. Robotic-assisted surgeries are beginning to find their place in urologic surgery. The surgical robot is ideally suited for the reconstruction of the ureteropelvic junction and is a good procedure for the novice robotic surgeon to attempt.

Indications for surgical intervention in patients with ureteropelvic junction obstruction include functionally significant obstruction, as defined by the presence of flank pain or other symptoms associated with the obstruction, impairment, or deterioration in renal function.

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