Urethral Valves vs. Detrusor Sphincter Dyssynergy
Left picture: Due to the shape of the flow curve and the decreased flow rate, an infravesical obstruction must be present; in this case, according to the radiological (VCUG) and endoscopic (cystourethroscopy) imaging, the diagnosis is a slight type of posterior urethral valves. Right picture: The shape of the flow curve and the delayed maximum flow rate caused by an episodic pelvic floor activity are typical for a detrusor sphincter dyssynergy which is a type of functional voiding doisorders of the bladder. It occurs in girls as well as in boys.
Left picture: Uroflowmetry in a 4.1-year-old boy with a weak urinary stream. Instead of a bell-shaped flow curve there is a flattened curve. With a micturation volume of 169 ml the flow rate amounts to 7.8 ml/s (the normal value is equal to or higer than 10 ml/s in a micturation volume higher than 100 ml). Right picture: Uroflowmetry in a 7.5-year-old schoolchild with recurrent urinary tract infection, weak urinary stream and a somewhat softer than usual micturation noise. Instead of a bell-shaped flow curve there is a flattened curve. The micturation is hindered by repeated activities of the pelvic floor; look at the electromyography below the flow curve with two episodes of distinct activities, each one lasting between 0 to 5 and 5 to 10 seconds; therefore, the maximum flow rate of 17.1 ml/s (micturation volume of 127 ml) is attained only after half of the micturation time has passed.