Invasive urodynamic tests are used to measure nerve and muscle function, pressure around and in the bladder and other factors that might help to explain why a child may experience voiding symptoms. Voiding symptoms may include a slow stream of urine, spraying of urine, difficulty in beginning urination and dribbling of urine. These symptoms can be extremely embarrassing and distressing for affected children and may dictate or restrict how they live their lives. Results of invasive tests might reveal the cause of the voiding symptoms, thereby guiding healthcare providers in choosing the most effective treatment.