AIM OF STUDY

The symptomatic diagnosis of an “overactive bladder” (OAB) has been defined as the symptoms of urinary frequency greater eight times a day associated with urgency or urge incontinence ¹. At present there is debate within the ICS about using the term “overactive bladder”, a classification which has been proposed for use in the primary care setting for the prescription of anticholinergic therapy.

This study attempts to determine whether the “overactive bladder” is a useful term to select women for treatment and wheather the women selected can safely be initiated on treatment.

 

METHODS

All women were referred to the urodynamic clinic because of lower urinary tract symptoms. They underwent a clinical evaluation including complete history, vaginal examination, frequency-volume chart and videocystometrogram (VCMG). After uroflowmetry, the urinary residual was measured and the bladder filled at 100 ml/min with room temperature contrast medium. The bladder was imaged at maximum bladder capacity and provocative manoeuvres were undertaken. Finally a pressure-flow study was performed and the urinary residual measured. All terms and definitions are in accordance with International Continence Society (ICS). Women with symptoms consistent with an overactive bladder were chosen.

RESULTS
4500 consecutive women were studied. Only eight hundred forty three women (18.7%), who complained of frequency, nocturia, urgency and urge incontinence could be classified as having an overactive bladder. Four hundred and fifty seven women (54.2%) had detrusor instability, while 386 women (45.8%) had a stable urodynamic trace. Sixty eight (8.1%) of the women studied had voiding difficulties. The urodynamic diagnoses are shown in table 1. The post void residuals after the free flow rate at the beginning of urodynamics are displayed in table 2.

 

 

 

Genuine stress incontinence	Pure Unstable bladder	Mixed incontinence	Voiding difficulties	Other
176	327	130	68	142
20.8%	38.8%	15.4%	8.1%	16.9%

 

Table 1. Urodynamic diagnoses of the women with symptoms of an ”overactive bladder”.

One hundred and eleven women (13.3%) had a urinary residual greater than 50 ml and a few women (7) had urinary residuals greater than 400 ml.

Detrusor instability was diagnosed in 1857 women (41.6%) of the original 4500 women.

Post void residual	< 50 ml	50 to 100 ml	100 to 200 ml	200 ml<
N. patients	732	42	49	20
%	86.7	5.2	5.9	2.2

 Table 2. Post void residuals after a free flow rate of the women with symptoms of an ”overactive bladder”

CONCLUSIONS

The diagnosis of  ”overactive bladder” using urinary symptoms under diagnoses detrusor instability in a population of women suffering from lower urinary tract symptoms. Treatment for detrusor instability would be inappropriate in half of those women with the symptomatic diagnosis of  ”overactive bladder ” and a significant minority of women have post-void urinary residuals greater than 100 ml (8.1%). Anticholinergic therapy in the later group may lead to urinary retention. The symptomatic diagnosis of overactive bladder is not recommended.

REFERENCES
[1] Kobelt G. Kirchberger I., Malone-Lee J. Review. Quality of life aspects of the overactive bladder and the effect of treatment with tolterodine. BJU International 83(6):583-90,1999.