Editing CUA: Antenatal hydronephrosis (2017) (section)

== Grading ==
* Descriptors such as mild, moderate, or severe should not be used in isolation, as they are subjective and undefined

=== Hydronephrosis ===
*'''Grading systems for the severity of antenatal hydronephrosis (3):'''
*# '''Antero-posterior renal pelvic diameter (APD)'''
*#'''Society of Fetal Ultrasound (SFU) classification'''
*#'''Urinary tract dilation (UTD) classification'''

==== Antero-posterior renal pelvic diameter (APD) ====
* Simplest form grading
{| class="wikitable"
|'''Degree of antenatal hydronephrosis'''
|'''Second trimester'''
|'''Third trimester'''
|-
|Mild
|4 to ≤6 mm
|'''7 to ≤8 mm'''
|-
|Moderate
|7 to ≤10 mm
|'''9 to ≤15 mm'''
|-
|Severe
|>10 mm
|'''≥16 mm'''
|}

==== Society of Fetal Ultrasound (SFU) classification ====

* Standard among pediatric urologists

{| class="wikitable"
|'''Grade'''
|'''Ultrasound findings'''
|-
|'''0'''
|'''Normal kidney (resolved antenatal hydronephrosis)'''
|-
|'''1'''
|'''Pyelectasis'''
|-
|'''2'''
|'''Pyelectasis with dilation of 1 or more major calyces (caliectasis)'''
|-
|'''3'''
|'''Pyelectasis with dilation of all 3 major calyces'''
|-
|'''4'''
|'''Pyelectasis with parenchymal thinning compared to contralateral kidney'''
|}

==== Urinary tract dilation (UTD) classification ====
* Proposed by SFU; combines elements of both APD and SFU
* Uses a 3-point system '''based on 6 different observations''' (renal pelvis APD, calyceal dilation, parenchymal thickness/appearance, ureteral dilation, and bladder abnormalities) to '''stratify patients into 3 risk categories''' (P1, P2, and P3) based on the most concerning of 6 US variables:
** UTD P1 (low-risk) with 10‒15 mm renal pelvis APD and central calyceal dilation to UTD P3 with renal pelvis APD >15 mm, peripheral calyceal dilation, parenchymal thinning, ureter dilation, and or bladder abnormality (high-risk).

=== Hydroureteronephrosis ===

* '''SFU Severity of hydroureteronephrosis (HUN) based on the transverse measure of the distal ureter''':
** Grade 1 is <7 mm
** Grade 2 is 7‒10 mm
** Grade 3 is >10 mm.