Objective To determine the prevalence and outcome of lower urinary tract obstruction (LUTO) using a large population-based congenital anomaly register.

Methods A retrospective population based study. Cases of LUTO were selected for a 13 year period (1995–2007) covering a birth population of 851 404. Cases were identified using data from a population-based Congenital Anomaly Register (WMCAR – West Midlands Congenital Anomaly Register) using ICD10 codes and keyword terms. Diagnoses were validated using additional datasets from Regional tertiary fetal medicine, perinatal pathology and paediatric services.

Results The total prevalence for LUTO was 3.34 (2.95–3.72) per 10 000 births, and the live birth prevalence was 2.24 (1.93–2.56) per 10 000 live births. Of the LUTO cases (n=284) 77.8% were isolated anomalies, the remainder associated with other structural or chromosomal anomalies. The majority of cases were male fetuses of which 79.6% were isolated, for female fetuses 9.7% were isolated. Outcome data were 69 TOPs (33%), 11 IUDs (3.9%) and 190 live births (66.9%). Perinatal mortality was 458 per 1000 births for complex cases and 120 per 1000 live births for isolated cases. When the cohort is restricted to isolated, non-female, singleton fetuses, there were 211 cases (74.3% of all LUTO), total prevalence 2.48 (2.14–2.81) per 10 000 live births. However, the prenatal diagnosis rate of LUTO within this group was 46.9% (99/211), reducing the proportion further that could have vesico-amniotic shunting.

Conclusion This is the largest population based HTA funded study of LUTO and thus gives accurate data for prevalence of disease. The data confirm that when the condition is isolated the most likely diagnosis is PUV and this is almost exclusively found in male fetuses.