Ureteropelvic junction (UPJ) obstruction implies a functional impedance of urinary flow at the anatomic junction of the renal pelvis and the ureter (Figure 1). A variety of obstructive processes may lead to UPJ obstruction and disruption of ureteral peristalsis. Primary causes include primary intrinsic narrowing owing to defects in the ureteral musculature, extrinsic compression by crossing vessels or fibrous bands, and abnormal high insertion of the ureter into the renal pelvis. Secondary causes of ureteral obstruction result in fibrosis following renal calculus disease, renal infection, iatrogenic injury, and renal trauma.<sup>21 Thomas R. Ureteroscopic retrograde endopyelotomy Video Urology Times 1992 ;  5 : 1

Cliccare qui per andare alla sezione Riferimenti, 22 Thomas R. Endopyelotomy for ureteropelvic junction obstruction and ureteral stricture disease: A comparison of antegrade and retrograde techniques Curr Opin Urol 1994 ;  4 : 174-179  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti, 23 Thomas R. Ureteral surgery: Retrograde endopyelotomy for uretero-pelvic junction obstruction Smith's Textbook of Endourology St. Louis: Quality Medical Publishing (1996).  489-496

Cliccare qui per andare alla sezione Riferimenti, 24 Thomas R., Monga M., Klein E.W. Ureteroscopic retrograde endopyelotomy for management of uretero-pelvic junction obstruction J Endourol 1996 ;  10 : 141-145  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup>

Historically, open pyeloplasty has been the mainstay of operative correction of UPJ obstruction. With the advent of endourologic techniques and technology, several minimally invasive procedures are being applied to UPJ obstruction: antegrade nephroscopic endopyelotomy, retrograde ureteroscopic endopyelotomy, balloon dilation with a cutting wire (Acucise), and laparoscopic pyeloplasty. It has been suggested that laparoscopic pyeloplasty is more effective than antegrade percutaneous endopyelotomy and Acucise endopyelotomy; however, this study did not include retrograde ureteroscopic endopyelotomy in the evaluation.<sup>11 Inglis J.A., Tolley D.A. Ureteroscopic pyelolysis for pelvic ureteric junction obstruction Br J Urol 1986 ;  58 : 250-252  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup>

The retrograde technique of endopyelotomy has evolved with the rapid improvements in ureteroscopic instrumentation.<sup>7 Clayman R.V., Basler J.W., Kavoussi L. , e al. Ureteronephroscopic endopyelotomy J Urol 1990 ;  144 : 246-252

Cliccare qui per andare alla sezione Riferimenti, 13 Meretyk I., Meretyk S., Clayman R.V. Endopyelotomy: Comparison of ureteroscopic retrograde and antegrade percutaneous techniques J Urol 1992 ;  148 : 775-782

Cliccare qui per andare alla sezione Riferimenti</sup> Initial studies suggested a high rate of ureteral stricture formation,<sup>13 Meretyk I., Meretyk S., Clayman R.V. Endopyelotomy: Comparison of ureteroscopic retrograde and antegrade percutaneous techniques J Urol 1992 ;  148 : 775-782

Cliccare qui per andare alla sezione Riferimenti, 20 Streem S., Geisinger M.A. Prevention and management of hemorrhage associated with cautery wire balloon incision of UPJ obstructions J Urol 1995 ;  153 : 1904  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> which has been attributed to thermal injury from transmission of the electrocautery current.<sup>22 Thomas R. Endopyelotomy for ureteropelvic junction obstruction and ureteral stricture disease: A comparison of antegrade and retrograde techniques Curr Opin Urol 1994 ;  4 : 174-179  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> Current use of an insulated ureteroresectoscope with a fixed right-angle electrode has alleviated this problem.<sup>22 Thomas R. Endopyelotomy for ureteropelvic junction obstruction and ureteral stricture disease: A comparison of antegrade and retrograde techniques Curr Opin Urol 1994 ;  4 : 174-179  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti, 24 Thomas R., Monga M., Klein E.W. Ureteroscopic retrograde endopyelotomy for management of uretero-pelvic junction obstruction J Endourol 1996 ;  10 : 141-145  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> In comparison with the antegrade approach, the retrograde approach eliminates the risks associated with percutaneous access to an upper or middle pole calyx (hydrothorax, pneumothorax) and the need for external nephrostomy tube drainage. Expanded experience with retrograde ureteroscopic endopyelotomy has made this approach an important part of the minimally invasive armamentarium for endoscopic management of UPJ obstruction.