The common clinical presentation of older men with symptoms such as frequent urination, urinary urgency, increased nocturia and thinning of the urinary line, shortening of the ejaculation, dribbling of urine and urinary retention have mostly been attributed to prostatic hyperplasia, a view that has been accepted by the vast majority of clinicians. However, with the progressive understanding of urodynamics, more and more urologists are realizing that these symptoms are not solely due to prostate enlargement. This explains the lack of significant clinical improvement in patients’ urinary hesitancy symptoms after prostate surgery.
Normal urinary function depends on normal bladder function and normal urethral function, and the two must remain in harmony with each other. The normal voiding process is the contraction of the bladder accompanied by the opening of the urethra. If the urethra does not open for some mechanical reason when the bladder begins to contract, or if it opens very little, this results in a high bladder pressure and low flow rate during urodynamic testing, suggesting bladder outlet (organic) obstruction.
Generally this is prostatic hyperplasia. If the urethra has opened and the bladder does not contract or has very poor contraction and still cannot urinate properly, then increased abdominal pressure is needed to urinate, this is what we call impaired or weak contraction of the detrusor muscle.
There are two other conditions.
One is a synergistic dysfunction of the bladder forcing muscle and urethral sphincter, which is manifested as a great effort when starting to urinate, and an increase in bladder pressure can be seen at the beginning of manometry, and once there is urine discharge the pressure drops rapidly, and a high flow rate can be maintained at a very low pressure.
Secondly, it can show a high pressure and high flow rate curve, which we think is still the result of increased pressure in the bladder to overcome urethral resistance, and this type is more likely to produce vesicoureteral reflux and cause pelvic and ureteral effusion. The above four conditions, especially the first two, are the most common in clinical urodynamic examinations. It should be noted that it is very difficult to differentiate between the processes that produce lower urinary tract symptoms without appropriate urodynamic testing.
In clinical treatment work, in elderly male patients with LUTS symptoms, the prostate is objectively enlarged to varying degrees, but it is another question of recognition whether the enlarged prostate tissue is actually compressing the urethra and causing difficulty in urination.
The prostate is a reproductive gland that surrounds the urethra below the bladder, and it is generally believed that after the age of 50, men begin to experience degeneration and hyperplasia of the gland due to changes in sex hormones in the body. However, by observation, not all older men present with significant difficulty urinating and all require surgery or medication.
This gives us a hint that.
(1) The hyperplastic prostate tissue grows toward the periphery of the urethra, sometimes in such a large size that it can not compress the urethra or mildly compress it so that normal urination can occur through the compensatory mechanism of the bladder.
②The size of the prostate gland cannot be proportional to the symptoms of dyspareunia. A very small volume of prostatic hyperplastic tissue, growing toward the urethra, can easily compress the urethra and cause difficulty in urination.
The strength of the contraction of the bladder force is another important reason for difficulty in urination. If the contraction of the bladder forcing muscle is poor, further surgical or conservative treatment for the prostate will be pointless, even if the prostate enlargement is obvious. This group of cases showed that of the 141 patients who clearly had prostatic hyperplasia, only 96 had bladder neck obstruction (68%) by urodynamic examination, and the remaining 45 had reduced bladder contraction (31%).
Accordingly, 98 cases were treated surgically, two of which had hypocystic bladder contraction with a maximum force of the detrusor less than or equal to 40 cmH2O. Further illustrating the importance and necessity of preoperative assessment of bladder forceps function, forceps dysfunction would be the main cause of LUTS failure due to surgical treatment of prostate enlargement.
There are several reasons for producing a diminished contractility of the detrusor muscle.
(1) Aging of the bladder’s own tissues and poor contractile function in elderly patients;
(2) Impaired function of the forceps muscle, mostly seen in female patients with a history of habitual urinary retention, and others such as patients with acute and chronic urinary retention can lead to varying degrees of impaired function of the forceps muscle;
(iii) Diabetes mellitus causes damage to the peripheral nerves of the bladder;
(iv) spinal cord injury and lesions, central neuropathy, multiple sclerosis, etc.
For patients with acute urinary retention and overfilled bladder with prostatic hyperplasia, the bladder is overfilled for a long time so that the bladder muscle is over-extended and gradually loses its tone and effective contraction ability. In patients with long term chronic urinary retention, if the urodynamic examination reveals incompetence of the bladder forcing muscle contraction, cystostomy or indwelling catheterization can be performed first, and then surgery can be performed after the function of the forcing muscle is restored on follow-up.
Urodynamic examination is an important guide to the long-term outcome and perioperative management of BPH. In comparing the results of pressure-flow rate examination and the improvement of patient’s symptoms after surgery, we analyzed that the cut-off line is 40 cmH2O to 60 cmH2O of forceps pressure, and we do not recommend surgical treatment for forceps pressure less than or equal to 40 cmH2O. Preoperatively, patients should be informed that there may be a significant difference in the expected outcome.
In patients with an unstable bladder combined with hypocompliant bladder (overactive bladder), preoperative and postoperative treatment with competitive M-cholinergic receptor blockers can prevent and control unstable bladder contractions, reduce postoperative spastic bleeding, and decrease the incidence of postoperative urinary frequency and urgency. Urethral pressure measurement can pre-consider the pressure change curve of the urethra in each prostate department between the bladder neck and the external urethral sphincter, thus obtaining data on the length of the urethra in the prostate department, as well as the distribution of the main obstructive areas, which provides an important clinical theoretical basis for surgical resection of the prostate by TURP.
Although urodynamic testing is not a recommended test in the BPH guidelines, we still believe that it is important to perform urodynamic testing before prostate surgery.
(1) It can distinguish the cause of LUTS from organic obstruction, and if it is not, surgical treatment will be ineffective;
(ii) It should not be overlooked that incompetence of the bladder muscles is another important cause of LUTS symptoms;
③Provide a more realistic and powerful therapeutic basis for the evaluation of treatment outcome and perioperative management;
④The relationship between bladder pressure and urethral resistance can be truly reflected by urodynamic examination, which increases the success rate of surgery and greatly reduces the occurrence of medical disputes.