Objective: To ascertain the aetiology and epidemiology of non-neurogenic bladder sphincter dysfunction (NNBSD) by assessing the results of prospective video-urodynamic studies (VUD) in 1000 children.
Patients and methods: During a 4-year study period (January 1995 to December 1998) 1000 children prospectively underwent VUD to further define their NNBSD. After a noninvasive screening assessment consisting of a history, voiding diary, clinical examination, urine analysis, ultrasonography and uroflowmetry, those children who would benefit from further VUD were selected. The selection criteria included a history of urinary tract infection (UTI), a small bladder capacity not responding to training, dysfunctional uroflow, ultrasonographic abnormalities and resistance to therapy. During the study period 3500 children were screened for incontinence problems, including monosymptomatic nocturnal enuresis; 1000 of these were selected for VUD (524 boys and 476 girls).
Results: The urodynamic diagnosis was of normal bladder-sphincter function in 62 (6.2%, male : female 44 : 56), urge syndrome in 582 (58%, 58 : 42), dysfunctional voiding in 316 (32%, 49 : 51) and 'lazy bladder' in 40 (4%, 20 : 80). Boys diagnosed with a 'lazy bladder' were younger than those with urge syndrome and dysfunctional voiding. Girls with dysfunctional voiding were younger than those with urge syndrome. The incidence of UTI was significantly higher in girls than in boys; boys with NNBSD had no greater risk for UTI and in girls the general risk was 34%. Only in girls with a lazy bladder was there a significantly higher incidence of UTI (53%). Reflux occurred equally in all groups, with an overall incidence of 15%. The incidence of obstipation was significantly higher in girls with a lazy bladder, and overall was 17%.
Conclusion: These results from a large series provide a new insight into the epidemiology and pathophysiology of NNBSD. The age distribution provides evidence against a dysfunctional voiding sequence. The risk of developing UTI in NNBSD is greater only in girls. In children with a lazy bladder the risk is also significantly higher, indicating that residual urine is a greater risk factor than detrusor instability. Urge syndrome and dysfunctional voiding in girls carry the same risk for developing UTI, indicating that bladder instability is a higher risk factor for UTI than detrusor sphincter discoordination. All dysfunctions carry an equal risk for developing secondary reflux. Children with NNBSD have different primary diseases but all have a common risk of incontinence, UTIs, reflux and obstipation.