Summary
Introduction
The anteroposterior diameter (APD) of the renal pelvis is a commonly used ultrasound
parameter in the evaluation and management of hydronephrosis. It has been established
that an APD value associated with pyeloplasty is around 25 mm. Some believe the APD
should be measured at the innermost part of the renal pelvis while others suggest
that it should be done at the renal contour. However, there is no consensus on the
optimal APD measurement technique including whether it should be measured supine or
prone. This study compared six different techniques of APD measurements, in both supine
and prone positions, and further evaluated their association with pyeloplasty.
Methods
Data was obtained by retrospectively reviewing patients’ charts that had initial high-grade
hydronephrosis (HGH) from 2008 to 2014. We recorded the patients’ demographics, ultrasound
data and management choice. In the mid-renal transverse plane, the APD was measured
by 2 blinded investigators, at the intra-renal, renal contour and extra-renal regions
of the renal pelvis in supine and prone positions (Figure A). We compared the six APD measurements based on the outcome of management (pyeloplasty
vs. conservative management). The ROC curve obtained was then used to assess the ability
of various APD measurements in predicting surgical intervention. The cutoff value
chosen that predicts pyeloplasty was the lowest diameter with 100% specificity.
Results
We included 129 patients (134 renal units). Forty-four renal units (42 patients) underwent
pyeloplasty whereas 90 renal units (87 patients) were managed conservatively. Patients’
demographics were grouped by both SFU grade and clinical outcome. Regardless of grade, the APD
measurements were different in all 6 techniques. All APD measurement techniques showed
good inter-rater reliability. Based on the ROC curve, all APD measurements were associated
with pyeloplasty with an AUC from 0.89 to 0.91. The supine extra-renal APD measurement
of 24 mm was the most sensitive cutoff value. The cutoff values ranged from 18 to
27 mm when including patients from all grades of hydronephrosis. The median APD measurements
were significantly less for SFU grade 3 than grade 4 hydronephrosis in all positions
(P < 0.001 for all measurements), yet the predictive cutoff value of 24 mm for the
supine extra-renal was similar for both grades.
Conclusion
Graphical AbstractIllustrates how APD was measured in supine (a) and prone (b) transverse mid-renal
views at the intrarenal pelvis, renal contour and extrarenal pelvis locations.
Keywords
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Article info
Publication history
Published online: August 19, 2022
Accepted:
August 12,
2022
Received in revised form:
August 9,
2022
Received:
December 3,
2020
Identification
Copyright
© 2022 Published by Elsevier Ltd on behalf of Journal of Pediatric Urology Company.
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- Comment to: “How can we measure the renal pelvic anteroposterior diameter in postnatal isolated hydronephrosis? Amr Hodhod, Hadeel Eid, John-Paul Capolicchio, Francis Petrella, Iman Sadri, Mohamed El-Sherbiny, Roman Jednak, Caroline Lacroix”Journal of Pediatric UrologyVol. 19Issue 1
- PreviewWe read with great interest the study by Dr Hodhod et al. who compared six different techniques for measuring anteroposterior diameter (APD) of the renal pelvis [1]. They found little difference in APD according to patient position, but did find a significant difference between intrarenal, renal contour and extrarenal APD.
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