Fetal bladder outflow obstruction is a congenital ‘blockage’ of the tube connecting the bladder neck to the external part of the baby (the urethra). This may cause permanent damage to the baby's kidneys (probably due to increased pressure) and can lead to poor lung development and physical deformities such as clubfoot.
Over all, about half of babies diagnosed with this problem before birth will die, either before birth or in the newborn period. For several years, treatment to relieve the obstruction (vesico-amniotic shunting) has been offered, but with only weak evidence that it improves survival and kidney function in those treated.
What was the PLUTO Trial?
Following an ultrasound diagnosis of fetal bladder outflow obstruction, eligibility and baseline characteristics were confirmed by standard assessments of renal function, a detailed ultrasound examination to exclude other co-existing anomalies and fetal karyotyping. If the mother consented to participation, the fetus was randomised to receive either a fetal vesico-amniotic shunt or continue with conservative management without a shunt.
The aim was to randomise 200 pregnancies from across the UK. The primary outcome measures were perinatal mortality and serum creatinine at 6 weeks of age. Secondary outcome measures included bladder and renal function, termination and miscarriage rates and resource usage. Initial follow-up of secondary outcomes continued to one year of age. Long-term follow-up of continence is planned at five years.
What did the study find?
The PLUTO trial randomised 31 pregnancies and collected information from another 46 pregnancies where the parents or clinicians elected for one management pathway or the other. The reasons we suspect contributed to slow recruitment were a lower than expected prevalence of fetal bladder obstruction, strong preferences for one option by the fetal medicine specialists and parents opting for termination of pregnancy upon diagnosis.
A parallel study involved parents who consented to the trial, opted for one treatment or opted for termination. These were approached for an interview to discuss their reasons for that choice. The results of the trial were published in 2013.
What impact did this study have?
As fetal bladder outlet obstruction is a relatively uncommon condition, this multicentre trial assessed the short and long-term effects of this intervention. Benefit could not be conclusively proven.
- Outcome in fetal lower urinary tract obstruction : a prospective registry. Morris RK, Middleton LJ, Malin GL, Quinlan-Jones E, Daniels J, Khan KS, Deeks J, Kilby MD. Ultrasound Obstet Gynecol. 2015 Feb 4; doi: 10.1002/uog.14808
- Evaluation of the cost effectiveness of vesico-amniotic shunting in the management of congenital lower urinary tract obstruction (based on data from the PLUTO trial). Diwakar L, Morris RK, Barton P, Middleton LJ, Kilby MD, Roberts TE. PLoS One. 2013 Dec 20;8(12):e82564. doi: 10.1371/journal.pone
- The Percutaneous shunting in Lower Urinary Tract Obstruction (PLUTO) study and randomised controlled trial: evaluation of the effectiveness, cost-effectiveness and acceptability of percutaneous vesicoamniotic shunting for lower urinary tract obstruction. Morris RK, Malin GL, Quinlan-Jones E, Middleton LJ, Diwakar L, Hemming K, Burke D, Daniels J, Denny E, Barton P, Roberts TE, Khan KS, Deeks JJ, Kilby MD. Health Technol Assess. 2013 Dec;17(59):1-232
- Percutaneous vesicoamniotic shunting versus conservative management for fetal lower urinary tract obstruction (PLUTO): a randomised trial. Morris RK, Malin GL, Quinlan-Jones E, Middleton LJ, Hemming K, Burke D, Daniels JP, Khan KS, Deeks J, Kilby MD. Lancet. 2013 Nov 2;382(9903):1496-50
- Effectiveness of percutaneous vesico-amniotic shunting in congenital lower urinary tract obstruction: divergence in prior beliefs among specialist groups. Brown C, Morris RK, Daniels J, Khan KS, Lilford RJ, Kilby MD. Eur J Obstet Gynecol Reprod Biol. 2010 Sep;152(1):25-9. Epub 2010 May 23.
- Systematic review of the effectiveness of antenatal intervention for the treatment of congenital lower urinary tract obstruction. Morris RK, Malin GL, Khan KS, Kilby MD. BJOG. 2010;117(4):382-90.
- Antenatal ultrasound to predict postnatal renal function in congenital lower urinary tract obstruction: systematic review of test accuracy. Morris RK, Malin GL, Khan KS, Kilby MD. BJOG. 2009;116(10):1290-9.
- An overview of the literature on congenital lower urinary tract obstruction and introduction to the PLUTO trial: percutaneous shunting in lower urinary tract obstruction. Morris RK, Kilby MD. Aust N Z J Obstet Gynaecol. 2009;49(1):6-10
- Vesicoamniotic shunting for fetal lower urinary tract obstruction: an overview. Morris RK, Khan KS, Kilby MD. Arch Dis Child Fetal Neonatal Ed. 2007;92(3):F166-8
- Congenital lower urinary tract obstruction: to shunt or not to shunt? Kilby MD, Daniels JP, Khan K.BJU Int. 2006;97(1):6-8.
- The PLUTO study the NIHR Health Technology Assessment program
For more information
Antenatal Results and Choices