A prospective study of the contribution of uroflowmetry in urodynamic investigation

Abstract

The definition and grading of voiding problems in women with lower urinary tract symptoms varies. Using various diagnostic criteria, a prevalence ranging from 6.6% to 20% has been quoted (Groutz et al ., 2000; Lemack et al ., 2000). Diagnosis often depends on a combination of history, free-flow uroflowmetry (FFU) and pressure flow studies (PFS). As most bladder neck operations can induce voiding problems or exacerbate an already existing voiding problem, the need to establish the voiding status of women before bladder neck operation is vital. An abnormal voiding pattern can either exclude surgical intervention or help in prior counselling of the patient about the risk of postoperative voiding problems and teach her intermittent self-catheterisation even before surgery. As voiding difficulty may not always become apparent from the history, the need for its exclusion by objective studies therefore exists. This depends on FFU and PFS. FFU is a simpler test and can be carried out in the outpatient setting. It could be performed without transurethral catheterisation if bladder urine residual is measured by ultrasound. The results of FFU are generally considered sufficiently accurate in making a diagnosis of voiding difficulty (Jorgensen et al ., 1998); however, combination of an abnormal result and its characterisation by PFS is ideal. For uroflowmetry to be informative and interpretable, the bladder must contain 150 ml of urine or more. Normal patterns by convention are expected to have a maximum flow rate of 15 ml or more with residual urine of less than 100 ml. Given its ease of performance and importance, the availability and contribution of FFU in the diagnosis of voiding problems in female urodynamics in our setting was investigated.