Effect of Voided Volume on Voiding Patterns and Reliability of Uroflowmetry-Electromyography Results in Children with Lower Urinary Tract Dysfunction.

Objective: To examine whether voided volume (VV) could change the uroflow patterns and result in children with lower urinary tract dysfunction (LUTD). Methods: Between January 2009 and May 2010, the children with LUTD were enrolled in this study. Uroflowmetry (UF) combined with electromyography (EMG) was performed two times and was reviewed independently by two urologists. UF-EMG curves were classified as bell, staccato, intermittent, plateau, and tower. Patients' expected bladder capacity (EBC) and VV were recorded. Patients were divided into four groups according to their VV and EBC. Group 1, VV < 50% of EBC; group 2, VV between 50 and 100% of EBC; group 3, VV between 100 and 125% of EBC; group 4, VV > 125% of EBC. Results: A total of 143 patients underwent UF-EMG at least two times and 382 results were obtained. Groups 1, 2, 3 and 4 consisted of 27, 60, 27 and 29 children, respectively. The percentages of normal, intermittent, plateau voiding patterns were 58.5, 12.8, 7.1% in group 1; 79.8, 5.4, 1.8% in group 2; 59.2, 8.5, 2.8% in group 3; and 37.2, 5.1, 2.6% in group 4, respectively. The percentages of staccato and tower pattern were 1.4, 20% in group 1; 9.1, 3.6% in group 2; 30, 0% in group 3; and 55.1, 0% in group 4, respectively. The rate of tower shape curve decreased as voided volume increased, but the rate of staccato curve increased as voided volume increased. Conclusions: In case of exceeding the EBC, the test should be repeated with normal VV when UF results are being evaluated.