121 / 492
11:40 - 11:43
S8-3
(PP)
PERCENT IMPROVEMENT IN RENAL PELVIS ANTEROPOSTERIOR DIAMETER
IMPROVEMENT (APDI): VALIDATION AND FURTHER EXPLORATION OF CUT-OFF
VALUES THAT PREDICT SUCCESS POST-PYELOPLASTY AND SAFE MONITORING
WITH ULTRASOUND ALONE
Mandy RICKARD
1
, Jennifer D'CRUZ
2
, Armando LORENZO
3
, Carline BOZZATO
1
, Rodrigo ROMAO
4
, Natasha BROWNRIGG
5
,
Jorge DEMARIA
1
and Luis BRAGA
1
1) McMaster University - McMaster Children's Hospital, Department of Surgery / Urology, Hamilton, CANADA - 2)
McMaster University - McMaster Children's Hospital, McMaster Pediatric Surgery Research Collaborative, Hamilton,
CANADA - 3) The Hospital for Sick Children, Department of Surgery / Urology, Toronto, CANADA - 4) Dalhousie
University, Department of Surgery / Urology, Halifax, CANADA - 5) McMaster Children's Hospital, Department of Surgery
/ Urology, Hamilton, CANADA
PURPOSE
Renogram is frequently ordered post-pyeloplasty to confirm adequate drainage in patients with residual hydronephrosis
(HN). Recent evidence suggests that percent AP diameter improvement (APDI) ≥38% is predictive of pyeloplasty
success. We sought to further explore APDI ranges that would allow identification of patients who would require follow-
up with US alone, a post-operative renal scan and those with recurrent ureteropelvic junction obstruction (rUPJO).
MATERIAL AND METHODS
Our prospectively collected pyeloplasty database (2008-15) was reviewed (n=135). Only patients with both pre and
post-operative APD measurements were included (n=125;93%). APDI was divided into 3 categories: 0-19%; 20-39%;
≥40%. The following variables were collected post-operatively: patients monitored with US alone, renogram and US,
rUPJO and minimal or resolved HN (APD<15mm).
RESULTS
Mean minimum follow-up was 7.3±7.3 months. Of 125 patients, 76(61%) had US alone, 49(39%) had a renogram and
US, and 6(4%) developed rUPJO. Of 76 patients who had US alone, 54 (72%; p<0.01) demonstrated ≥40%APDI. Of 49
patients with renogram and US 31(63%; p<0.01) had ≥40%APDI. Of 78 patients with post-pyeloplsty APD<15mm,
65(83%; p<0.01) had ≥40%APDI. Table 1 shows descriptives for these variables.
CONCLUSIONS
Documentation of ≥40%APDI at the first post-operative visit strongly predicts pyeloplasty success, as 84% of these
patients showed minimal or resolved HN and 72% underwent non-invasive monitoring by US alone. Our data suggests
that up to 63% of renograms may have been unnecessary. Finally, ≤20%APDI permitted identification of all rUPJO
cases. Stratification of patients based on APDI is a promising strategy for minimizing radiation exposure while safely
detecting children at risk for rUPJO.
Table 1
APDI Ranges
0-19% 20-39% ≥40% p Value
US Only
n=76 (%)
11(14) 11(14) 54(72) <0.01
Renogram + US
n=49(%)
11(23) 7(14)
31(63) <0.01
Total
n=125
22
18
85
APD<15mm
n=78(%)
4(5)
9(12)
65(83) <0.01
rUPJO
n=6%
6(100) 0
0