Back to 2014 Fall Congress Meeting Abstracts

BACKGROUND: Pediatric ureteropelvic junction obstruction (UPJO) is caused by congenital intrinsic narrowing and/or a lower pole crossing renal artery. When a crossing vessel is missed at time of pyeloplasty, a redo-pyeloplasty is often required. This study analyzes clinical predictors for the presence of a crossing vessel in UPJO as well as the utility of computed tomography (CT) and Magnetic Resonance Urography (MRU) in preoperative identification of a crossing vessel.
METHODS: Using an Institutional Review Board approved registry database, we retrospectively identified 166 patients from July of 2007 until January of 2014 who underwent open, laparoscopic, or robotic assisted laparoscopic pyeloplasty at our institution. We abstracted data including: gender, age at surgery, pre-operative symptoms, pre-operative imaging findings, and whether or not a crossing vessel was identified intraoperatively. Statistical analysis was performed on SPSS using the Mann-Whitney U Test.
RESULTS: Of the 166 patients identified, 78 were found to have a crossing vessel at the time of surgery and 88 did not. The surgical approach was distributed as: 104 robotic assisted laparoscopic; 51 open; and 11 pure laparoscopic. On univariate analysis, older age at presentation and pain at presentation predicted the presence of a crossing vessel; antenatal hydronephrosis and increased degree of hydronephrosis were negative predictors (see table below). A total of 29 of the 78 crossing vessels were identified preoperatively on imaging. 18 out of 42 CT scans identified a crossing vessel when it was present, and 21 out of 55 MRU scans correctly identified a crossing vessel (PPV for all abdominal imaging=72.5%, and PPV for MRU alone = 69.6%).
CONCLUSION: This study confirms the need to maintain a high index of suspicion for the presence of a crossing vessel when intervening in a clinically symptomatic older child or in a pediatric patient without a higher grade of hydronephrosis. But the finding that even the most advanced imaging modalities fail to reliably detect a crossing vessel, and that even 25% of the crossing vessel cohort was comprised of infants with antenatally detected hydronephrosis confirms the need to remain vigilant for a crossing vessel during surgical intervention in every case of UPJO.

UPJ OBSTRUCTION FEATURES

	Crossing Vessel + n=78 n(%)	Crossing Vessel - n=88 n(%)	p value
Median age at surgery (years)	8.27	0.95	<0.001
Pain at presentation	56 (71.8)	28 (31.8)	<0.001
Antenatal diagnosis	20 (25.6)	68 (77.3)	<0.001
Hx UTI	19 (24.4)	12 (13.6)	0.078
Hx Stone disease	3 (3.8)	4 (4.5)	0.844
SFU Gr 1-2 Hydronephrosis	2 (3.8)	2 (2.4)	0.015
SFU Gr 3 Hydronephrosis	27 (51.9)	26 (31.7)	0.015
SFU Gr 4 Hydronephrosis	23 (44.2)	54 (65.9)	0.015
% Function	38.9%	37.8%	0.33