Long-term bladder function followup in boys with posterior urethral valves: comparison of noninvasive vs invasive urodynamic studies.

PURPOSE: We studied whether noninvasive urodynamic evaluation can be as effective and safe as invasive urodynamics in detecting lower urinary tract dysfunction and in preventing late onset renal failure during long-term management of boys with posterior urethral valves.

MATERIALS AND METHODS: We evaluated 47 boys with posterior urethral valves using repeat urodynamics. A total of 28 patients with followup of at least 3 years and repeat evaluation of serum creatinine were included in the study. The first 14 boys in the series underwent cystometry and pressure-flow study at least every 3 years (group A), and the remaining 14 patients were monitored annually from age 5 with bladder diary, uroflowmetry, post-void residual urine on ultrasound and serum creatinine (group B). Lower urinary tract dysfunction and serum creatinine were compared (Fisher exact test and Mann-Whitney test) between groups A and B, and by stratifying patients into subgroups by age (5 to 6, 7 to 13 and older than 13 years). In all patients urodynamic diagnosis of lower urinary tract dysfunction was matched and confirmed with lower urinary tract symptoms.

RESULTS: During followup the prevalence of lower urinary tract dysfunction did not differ significantly between group A (71% in boys 5 to 6, 43% in boys 7 to 13 and 85% in boys older than 13 years) and group B (36%, 43% and 60%, respectively). Late onset renal failure was observed in 2 boys in group A and 2 in group B.

CONCLUSIONS: Noninvasive urodynamic evaluation seems to be as safe and effective as invasive urodynamic study in the long-term management of boys with posterior urethral valves. Based on these findings, invasive urodynamics may be reserved for cases of progressive deterioration of lower urinary tract dysfunction or renal function.