Benign Prostatic Hyperplasia and Urodynamics

Facts:

BOO is present in 90% of men with larger prostates
(>80 ml), in those with small volumes (<40>15 ml/s only about 1/3 [3]. These data indicate that urine flow studies are not sufficient for the definitive
diagnosis of BOO (Abrams, BJUI 1995)

Obstructed patients do not always fare well with TURP (success rate: 79–93%) and conversely, unobstructed men do not always fail with success rates of 55–78% (Homma, BJUI 2001)

The EAU guidelines.

Who should have UDx prior to TURP?
(i) previous unsuccessful invasive treatment of LUTS;
(ii) elderly men (>80 years);
(iii) younger men (e.g. <50 years);
(iv) post-void residual volume >300 ml;
(v) suspicion
of neurogenic bladder dysfunction;
(vi) previous radical pelvic surgery


Previous unsuccessful invasive treatment

Nitti et al. have performed urodynamics studies in 50 consecutive patients referred because of persistent LUTS after prostatectomy. In this series, 62% of these men were urodynamically unobstructed, 22% were in the equivocal zone and only 16% were urodynamically obstructed; detrusor instability was present in 54%. Symptoms were unreliable in predicting urodynamic findings. These data clearly demonstrate that another deobstructing procedure (i.e. 2nd TURP) is unlikely solve the problem in this group of patients. Only pQs (urodynamics) can guide the appropriate treatment in these patients (Nitti, J Urol 1997)

Elderly patients

For two reasons, geriatric patients (>80 years) should undergo pQs prior prostatectomy. First of all, because morbidity of prostatectomy in this high age group is increased. Secondly, and equally important, is the fact that the ageing urinary bladder reveals a number of age related urodynamics changes in men [17,18]. Among these is a decrease of Qmax, an increase of post-void residual volume, a decline in bladder capacity and of bladder compliance. As a consequence
the percentage of patients without BOO despite a reduced Qmax of 10–15 ml/s and an interrnational Prostate Symptom Score (IPSS) exceeding 7 increases substantially in men older than 70 years and particularly above 80 years (Fig. 3) [17,18]. This observation is a strong argument for routine pQs in this high age group. The real predictive value of urodynamics on the outcome after surgery is also questionable. In a recent paper, van Venrooij (J Urol 2002) showed that in 32 unobstructed or equivocal patients, there was a 40% increase in mean effective capacity of the bladder after surgery which was correlated with the improvement
of symptoms. Furthermore, 50% of unstable bladders became stable after surgery, and this could not be predicted from urodynamics. Numerous studies show that more than 50% of
patients who would have been eliminated from surgery, according to PFS, are, in fact, improved after surgery.
This confirms that all symptoms in the presence of BPH do not correspond to obstruction, and that the latter may have different profiles on PFS. Patients with a weak detrusor should not be systematically eliminated from surgery. We should consider that the weaker the detrusor contraction is, the more important is the impact of an increase of urethral resistance. In such
patients, the relief of any degree of obstruction should improve micturition. There is an inherent limitation of PFS in detecting obstruction, when obstruction and a weak detrusor coexist, and a low detrusor pressure does not necessarily contraindicate prostatectomy. Operate on those who suffer failure with their conservative management. Some patients could benefit from minimally invasive therapies, but it has not yet been proven that urodynamics is able to differentiate
indications.


Urodynamics and success with TURP: Does obstruction make any difference to outcome.

No says Hakenberg et al: BJUI 2003

Variable
N
Age (yrs)
IPSS change
QOL



(improvements)
Pre Post
Ag Number














<15>40
46
72.5
9.5
5 1







AG# = Pdet at Qmax – 2(Qmax). >40 is obstrcucted, <20 is unobstructed, 20-40 equivocal



Outcome of TURP in pts with High Pressure Chronic Retention (Styles and Neal, J Urol 1991)
68 men with bladder outflow obstruction and chronic retention (residual urine greater than 300 ml.) Postoperatively, upper tract dilatation (present in 28 men preoperatively) resolved in all but 2 men and serum creatinine levels improved significantly. Irritative and obstructive symptom scores improved postoperatively (p less than 0.00006), although 17% of the men still had significant symptoms. Residual urine volumes decreased and flow rates improved (p less than 0.00006) 32% of the men still had a residual urine of greater than 200 ml.