81 Current epidemiology and antenatal presentation of Posterior Urethral Valves: Outcome of BAPS CASS national audit
Ewan Brownlee1, Ruth Wragg1, Andrew Robb1, Marian Knight2, Liam McCarthy1
1Birmingham Children's Hospital, Birmingham, United Kingdom. 2National Perinatal Epidemiology Unit, Oxford University, Oxford, United Kingdom


Aim of the study

Posterior urethral valves (PUV) are commonest cause of congenital bladder outlet obstruction (BOO) in boys, and of ESRF in childhood. In the 1990s 1/3 presented antenatally, 1/3 post-natally in infancy, 1/3 late (>1year). What proportion present antenatally, postnatally and late now? Are there any differences between these patient groups?


A national audit (BAPS CASS) of all referrals in the UK of boys diagnosed with suspected or confirmed PUV in a year was conducted. OPCS data provided male birthrate.

Data presented as number (%), analysed by Mann-Whitney U-test and Chi-square test, with p<0.05 taken as significant.

Ethics approval: NRES Committee South Central Oxford A (12/SC/0416)

Main Results

Data collected October 2014 - September 2015, 24/25 centres submitted data (96%). OPCS male birth rate: 398604/yr. 121 cases BOO; PUV 113 (93%). Incidence of BOO 1/3300; PUV 1/3500 per annum. PUV boys presented: antenatally 40(35%); in infancy 47(42%); late 26(23%).

Plasma creatinine higher in antenatally diagnosed BOO vs. postnatal, 54(39.5-109.5)µmols/l vs. 34(21-47)µmols/l, P=0.0005. Hydronephrosis and ureteric dilatation significantly greater in antenatally diagnosed BOO vs postnatal vs late. Renal dysplasia (cortical thinning, poor corticomedullary differentiation or renal cysts) significantly more likely in antenatally diagnosed BOO (see table).


Incidence of PUV has not changed in 30 years (~1/4000), nor the proportion antenatally diagnosed (~1/3). Boys antenatally diagnosed have significantly higher postnatal plasma creatinine, more hydro-ureteronephrosis and renal dysplasia than those diagnosed in infancy or late. It may be hypothesized that this is the reason they are detected antenatally.

US (at diagnosis) Antenatal Postnatal Late p
Renal Units 81 54 40  
APD* 9.5(0-19) 5.5(0-10) 0(0-9) 0.0001
Hydroureter* 5(0-8) 0(0-7) 0(0) 0.0025
Dysplasia 46(56%) 30(41%) 8(20%) 0.0007
*mm, median(IQR)