Open surgical dismembered pyeloplasty has traditionally been the preferred method for treating ureteropelvic junction obstruction (UPJO), with a success rate exceeding 94%. However, it is associated with drawbacks such as increased postoperative pain, extended hospital stays, and visible scarring. Minimally invasive alternatives, including laparoscopic pyeloplasty (LP) and robot-assisted laparoscopic pyeloplasty (RALP), have gained popularity since their introduction in 1993, offering comparable success rates to open surgery while providing cosmetic benefits and shorter hospital stays. Nevertheless, these techniques present challenges in pediatric patients, including limited working space, technical complexities, and prolonged operative times. The retroperitoneoscopic one-trocar-assisted pyeloplasty (OTAP) method, introduced in 2007, combines the advantages of minimally invasive surgery with the success rates of standard dismembered pyeloplasty. Despite favorable outcomes reported by several researchers, comprehensive studies regarding long-term follow-up and clinical outcomes are lacking. This study aims to evaluate the long-term outcomes of OTAP, addressing this gap in the medical literature.

Open surgical dismembered pyeloplasty has historically been the gold standard for managing ureteropelvic junction obstruction (UPJO), boasting a success rate exceeding 94%. However, the requisite incision and muscle dissection can lead to increased postoperative pain, prolonged hospitalization, and undesirable scarring. In recent decades, there has been a growing interest in minimally invasive pyeloplasty, commencing with its inception in 1993. Laparoscopic pyeloplasty (LP) and robot-assisted laparoscopic pyeloplasty (RALP) have emerged as widely embraced and dependable therapeutic modalities for UPJO. Both techniques have demonstrated success rates comparable to those of open pyeloplasty while conferring advantages in terms of cosmetic outcomes and length of hospital stay.

However, despite their merits, minimally invasive approaches pose certain limitations in pediatric patients, including restricted working space, technical intricacies, prolonged operative time, steep learning curves, and the need for expensive instrumentation. Conventional laparoscopic pyeloplasty has encountered slow uptake due to its technical demands and substantial learning curve. The evolution of RALP over the past decade appears to mitigate the learning curve associated with intracorporeal suturing and anastomosis time. Nonetheless, RALP necessitates three to four port placements and a sizeable initial financial investment.

In 2007, Lima et al. introduced the retroperitoneoscopic one-trocar-assisted pyeloplasty (OTAP) approach, which "combines the advantages of a minimally invasive technique with the high success rate of standard dismembered pyeloplasty". Several other researchers have replicated this technique with favorable outcomes. Nevertheless, a dearth of comprehensive studies delineating long-term follow-up and clinical outcomes persists in the medical literature. The aim of this study is to evaluate the long-term outcomes of OTAP.

Inclusion Criteria:

• Children 6 months to 5 years old with UPJ obstruction who underwent OTAP between May 2011 and June 2013.
• Anteroposterior renal pelvic diameter of 20 mm or greater, which demonstrated progressive enlargement on subsequent ultrasounds, coupled with impaired split renal function of 40% or less on nuclear scan, characterized by a T1/2 > 20 minutes
• The surgical technique performed must be one trocar-assisted pyeloplasty

Exclusion Criteria:

• A history of previous renal surgery
• UPJO associated with other urinary tract anomalies
• Identification of crossing lower pole renal vessels as the cause of obstruction.

The cohort comprised seventy pediatric patients who underwent RALP for UPJO at the National Hospital of Pediatrics between May 2011 and June 2013. Preoperative diagnostic evaluations included blood tests, urinalysis, urine culture, renal ultrasonography (US), voiding cystourethrogram (VCUG) to exclude vesicoureteral reflux disease, magnetic resonance imaging (MRI) to exclude other associated renal pathologies, and technetium-99m diethylenetriamine penta-acetic acid (99mTc DTPA) scans.