BACKGROUND: Congenital lower urinary tract obstruction (LUTO) is a disease associated with high perinatal mortality and childhood morbidity. Fetal vesicoamniotic shunting (VAS) bypasses the obstruction with the potential to improve outcome. OBJECTIVE: To determine the effectiveness, cost-effectiveness and patient acceptability of VAS for fetal LUTO. DESIGN: A multicentre, randomised controlled trial incorporating a prospective registry, decision-analytic health economic model and preplanned Bayesian analysis using elicited opinions. Patient acceptability was evaluated by interview in a qualitative study. SETTING: Fetal medicine departments in the UK, Ireland and the Netherlands. PARTICIPANTS: Pregnant women with a male singleton fetus with LUTO. INTERVENTIONS: In utero percutaneous VAS compared with conservative care. MAIN OUTCOME MEASURES: The primary outcome was survival to 28 days. Secondary outcome measures were survival and renal function at 1 year of age, cost of care and cost per additional life-year and per disability-free survival at the end of 1 year. RESULTS: The trial stopped early with 31 women randomised because of difficulties in recruitment. Of those randomised to VAS and conservative management, 3/16 (19%) and 2/15 (13%), respectively, did not receive their allocated intervention. Based on intention-to-treat analysis, survival at 28 days was higher if allocated VAS (50%) than conservative management (27%) [relative risk (RR) 1.88, 95% confidence interval (CI) 0.71 to 4.96, p?=?0.27]. At 12 months survival was 44% in the VAS arm and 20% in the conservative arm (RR 2.19, 95% CI 0.69 to 6.94, p?=?0.25). Neither difference was statistically significant. Of survivors at 1 year, two in the VAS arm had no evidence of renal impairment and four in the VAS arm and two in the conservative arm required medical management. One baby in the conservative arm had end-stage renal failure at 1 year. VAS was more expensive because of additional surgery and intensive care. VAS cost £15,500 per survivor at 1 year and £43,900 per disability-free year. Elicited expert opinions showed uncertainty in the effect of VAS at 28 days. In a Bayesian analysis combining elicited opinion with the results, uncertainty of the benefit of VAS remained (RR 1.31, 95% credible interval 0.84 to 2.18). The acceptability study identified visualisation of the fetus during ultrasound scanning, perceiving a personal benefit, and altruism as positive influences on recruitment. Fear of the VAS procedure and the perceived severity of LUTO influenced non-participation. The need for more detailed information about the condition and its implications during pregnancy and following delivery was a further important finding of this research. Recruitment was hampered by logistical and regulatory difficulties, a lower incidence of LUTO and lower antenatal diagnosis rate [estimated to be 3.34 (95% CI 2.95 to 3.72) per 10,000 total births and 47%, respectively, in an associated epidemiological study] and high termination of pregnancy rates. In the registry women also demonstrated a clear preference for conservative management. CONCLUSIONS: Survival to 28 days and 1 year appears to be higher with VAS than with conservative management, but it is not possible to prove benefit beyond reasonable doubt. Notably, prognosis in both arms for survival and renal function is poor. VAS was substantially more costly and unlikely to be regarded as cost-effective based on the 1-year data. Parents should be counselled about the risks of pregnancy loss with or without VAS insertion. The National Institute for Health and Care Excellence interventional procedures guidance (IPG 202) should be updated to reflect this new evidence. Babies in the PLUTO trial should be followed up long term for the different outcomes. TRIAL REGISTRATION: ISRCTN53328556. FUNDING: This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment ; Vol. 17, No. 59. See the NIHR Journals Library website for further project information.