• bladder diseases;
  • myelodysplastic syndromes;
  • urethral sphincter;
  • urinary catheterization

Objectives: This study was undertaken to investigate the influence of the urethral function on bladder shape and function in myelodysplastic children.

Methods: Of 39 myelodysplastic children, 30 were treated with intermittent catheterization. The diagnosis of internal sphincter incompetence (SI) was based on cystographic findings (open bladder neck) and that of external SI on urodynamic findings (underactive external sphincter identified on electromyography and maximum urethral closure pressure of less than 50 cm H2O). Follow up included evaluation of bladder deformity and compliance.

Results: The mean observation period was 8.6 years. In the 11 patients with external SI, bladder deformity and compliance significantly improved as a result of intermittent catheterization. However, of 12 patients with overactive sphincter and/or closure pressure of 50 cm H2O or more, eight showed deterioration or no improvement in bladder deformity, and three showed upper urinary tract deterioration.

Conclusion: These results indicate that an increase in urethral resistance may lead to deterioration of bladder shape.