Revisiting the Anatomy of the Pediatric Uretero-Pelvic Junction Analysis of Intraoperative Video of Robotic-Assisted Pyeloplasty

Abstract

Objective

To describe the ureteropelvic junction (UPJ) anatomy in children undergoing robotic-assisted pyeloplasty through analysis of high-resolution video.

Materials and Methods

Pediatric pyeloplasty recordings were examined, measuring pre- and post-spatulation ureteral diameters. Data on patient demographics, symptoms, hydronephrosis grade, renal function, and UPJ pathology were gathered to compare differences amongst UPJ obstruction etiology.

Results

Fifty consecutive robotic pyeloplasties by a single surgeon from over a 3-year period were reviewed, 45 (7 females, 38 males, mean age 5.5 years) were included, excluding two revisions and three poorly recorded cases. 67% had left-sided UPJ obstruction (UPJO). Thirty-one (69%) showed intrinsic UPJ narrowing with significant diameter reduction by an average of 1.1 mm, compared to the proximal ureter, both in vivo and after ureteral spatulation (P <.0001), with mean UPJ-to-normal ureter distance of 4.2 mm. Nine (20%) had crossing vessels, with 63% within 3 mm of the UPJ. Two (4%) had high inserting ureters, and three (7%) had ureteral polyps. Those aged 0-2 years (42%) universally had intrinsic narrowing of the UPJ. In older patients, 50% presented with abdominal/flank pain; among them, 56% with crossing vessels, 33% with ureteral narrowing, and 100% with high insertion. Patients with crossing vessels and polyps exhibited lower average split renal function (34.5% and 26%, respectively) compared to intrinsic narrowing and high insertion groups (both 47%).

Conclusion

Robotic pyeloplasty review details UPJ anatomy, emphasizing >1 mm of intrinsic UPJ obstruction narrowing, distance to normal caliber ureter (<8 mm, mean 4.2 mm), crossing vessel proximity (within 1.8 cm of UPJ), and normal ureteral caliber in polyps and high insertions. Analyzing UPJ anatomy offers surgical insights related to etiology, patient age, and presentation.