A comparative study between EMG uroflowmetry with and without a catheter in children

Objectives: To evaluate the effect of urethral catheterization on the accuracy of EMG uroflowmetry in children with non-neurogenic voiding disorders during pressure-flow (PF) studies compared to the non-invasive EMG uroflowmetry test. Methods: A retrospective study of children undergoing a urodynamic evaluation at our institution between 8/2018 and 7/2022 was employed. Urination curves and pelvic floor muscle activity were compared between PF studies and non-invasive EMG uroflowmetry test. The non-invasive test was selected as the standard benchmark. Results: 104 children were tested, with 34 children (33%) being able to urinate only in a non-invasive EMG uroflowmetry. The percentage of boys unable to urinate with a catheter was significantly higher than girls (54% vs. 13%, p-value < 0.001). In 70 children, a normal bell-shaped urination curve was found in 13 compared to 33 children in the PF studies and non-invasive uroflowmetry, respectively. PF studies demonstrated a specificity of 39% (95% CI 23–57) and a positive predictive value (PPV) of 61% (95% CI 53–67) in finding non-bell-shaped curves. Relaxation of pelvic muscles was found in 21 (30%) as opposed to 39 (55%) of children in invasive and non-invasive EMG uroflowmetry, respectively (p-value = 0.5). Conclusion: The accuracy of PF studies in children, primarily in boys, compared to the non-invasive uroflowmetry, was poor. This may pose potential errors in diagnosis and subsequent treatment. We recommend completing a non-invasive EMG uroflowmetry in cases where the child refused to urinate, or pathology was found, requiring a modification in treatment.