For several decades, open surgical pyeloplasty was the only method available for the repair of ureteropelvic junction (UPJ) obstruction. Over the past few years, several alternative techniques, such as antegrade and retrograde endopyelotomy and laparoscopic pyeloplasty, have been developed. Patients benefit from these new methods because they are all less invasive and carry lower morbidity than open surgery; however, there is considerable variation with regard to the morbidity involved and their efficacy in relieving obstruction. If the least invasive technique produced the best functional results equal to those of open surgery, the choice of procedure would be straightforward; however, a direct comparison of the morbidity associated with the different techniques is problematic because prospective randomized trials have not been undertaken. A direct comparison of the functional results is even more problematic because the degree of obstruction is difficult to quantitate. Obviously, good results achieved with one technique might be even better if a different method had been applied, but it is impossible to demonstrate and quantitate these potential differences in terms of outcome; therefore, the failure rate may be a more suitable parameter for comparison. A prospective randomized study comparing the different methods on the basis of identical criteria would settle the issue, but thus far, the minimally invasive techniques have been compared with historical series of open surgery only.<sup>4Bauer J.J., Bishoff J.T., Moore R.G., e al. Laparoscopic versus open pyeloplasty: Assessment of objective and subjective outcome J Urol 1999 ;  162 : 692 [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> In small series, the data are influenced by the learning curve as well.<sup>5Brooks J.D., Kavoussi L.R., Preminger G.M., e al. Comparison of open and endourologic approaches to the obstructed ureteropelvic junction Urology 1995 ;  46 : 791 [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> For ethical reasons, a prospective randomized trial comparing laparoscopy and open surgery cannot be performed because all studies report similar efficacy but great differences in morbidity. This argument does not apply to the comparison of different minimally invasive techniques, such as retrograde endopyelotomy versus laparoscopic pyeloplasty. These techniques are indicated for different groups of patients, and only long-term follow-up over many years could reliably reveal all treatment failures. A reduction in morbidity, which is the major advantage of the new techniques, must be weighted against potential disadvantages, as can be seen from the failure rates, when deciding on the most suitable treatment modality for a given patient.