Editing CUA: Antenatal hydronephrosis (2017) (section)

==== Renal-bladder US (RBUS) ====

===== <span style="color:#ff0000">Indications (1) =====
#'''<span style="color:#ff0000">APD ≥7 mm in third trimester'''
#*'''<span style="color:#ff0000">Verbatim (summary section): All significant AHN should be investigated with a postnatal RBUS. Most centres define significant AHN in the third trimester as APD ≥7 mm'''
#** ''Verbatim (RBUS section): All children with AHN should have a complete abdominopelvic US, with particular attention to both the kidneys and bladder. [likely meant “significant” ANH rather than "all" patients]''

===== Timing =====
* '''Avoid US in the first 2 days of life due to concern of understaging secondary to neonatal oliguria.'''
* The acceptable delay in the timing of the first postnatal US is controversial, with the SFU suggesting anywhere from 1‒4 weeks (see Figure 1 from Original Guideline for details, discussed below). '''In cases where immediate postnatal management is required such as PUV, US should not be delayed.'''

===== Technique =====

*Fasting for a RBUS is unnecessary.
*RBUS should include assessment of 
**Cranio-caudal length of the kidneys
**Degree of echogenicity and corticomedullary differentiation
**SFU grade of hydronephrosis
**Maximal APD on transverse axial view of the renal pelvis
**Diameter of both proximal and distal ureter if dilated
**Degree of bladder filling
**Detrusor thickness or presence of bladder trabeculation
**Diverticula
**Ureterocele
**Posterior urethral dilation in males.
* '''A full bladder should prompt a period of observation with re-imaging post-void to assess for the capability to empty the bladder and to assess whether the hydronephrosis improves post-void'''