Investigation Of Reconstruction Of Functional Urethra In Preventing The Incontinence After Radical Prostatectomy With Urodynamic Approach

Background:The prostatic cancer is the most common noncutaneous, newly diagnosed cancer in man and accounts for one third of newly diagnosed cancers and 9% of male cancer deaths, Radical prostatectomy (RP) is the most common treatment for localised prostate cancer in the United States, RP has excellent oncologic results. Incontinence and erectile dysfunction are the most common associated postoperative morbidities. The morbidities of post-RP incontinence is approximately 8-30% and the etiology is yet incomplete. Intrinsic sphincter deficiency and detrusor instability are believed to be the most important factors. At present, the prevention and therapeutic methods are limited and expensive, It has been a tremendous challenge for urological surgeon.The Role of functional urethra on urethral continence is very important, some studies have implied that functional urethral length may affect continence after RP. The longer the functional urethral length preserved during prostatectomy, the better continence obtained after RP. Coakley FV.et al. determined that a longer membranous urethra is significantly associated with rapid recovery of urinary continence after surgery according to endorectal MRI before RP. Multiple surgical techniques (which including bladder-neck preservation. the distal intraprostatic urethral length preservation and reconstruction of functional urethra using anterior bladder tube during prostatectomy) have been applied to improve post-RP continence by increasing the functional urethral length, All of these indicate that deficiency of functional urethral length was the most possible reason of incontinence after PR. However, the mechanism and degree of the impact of functional urethral length on urinary control are unclear. The current cant't explain these clinical phenomenon radically, Therefore, it is necessary to study systematic urodynamic evidence in terms of prevnting and treating the incontinence after RP.Objective: 1. To evaluate the influence of varing functional urethral length on urine controlling in order to demonstrate our novel theory: under the circumstance of the extrinsic factors of urethra(innervation and external urethral sphincter.et al.)are normal, the suitable length and function of the functional urethral are two important factors of urine controlling.2. To explore the new method of preventing and treating a series of diseases including urinary incontinence post-RP with systematic urodynamic research.Methods:1. The influence of the variation of functional urethral length on urine controlling:16 male dogs were divided into two groups randomly and tested urethral pressure profile and voiding cystometry before operation. Group A(n=8) is to test the different resting urethral pressure profile after resection of prostate, distant prostate plus 1.5cm and 2.0cm length posterior urethra respectively. Group B(n=8) is testing the different resting urethral pressure profile on 2.0cm and 1.0cm length pedicle myotube using anterior bladder flap respectively after resection of prostate plus 2.0cm length of posterior urethra.2. The change of reconstruction of functional urethra using anterior bladder flap pedicle myotube after radical prostatectomy on urine controllingAll dogs were divided into two groups and tested urethral pressure profile before operation. Group C (n=8, includies 3 of group A.) is to resect prostate plus 2.0cm length posterior urethra respectively, 7 dogs were survived. Group D(n=8, includes 2 of group A) is to reconstruct functional urethra using 1.0cm length anterior bladder flap pedicle myotube after resection of prostate plus 2.0cm length of posterior urethra, 6 dogs were survived. Two groups are to note the outcome of continence after the urinary canal was removed, and test the resting urethral pressure profile and Stress leak point pressures respectively in a month of post-operation.Results:1. The weight and urodynamic parameters of male dogs have no significant difference between groupA and B before operation(p>0.05). The urodynamic parameters fell off while the functional urethral length decurtation gradually in group A. However, the converse situation is seen in group B while the functional urethral length incremental gradually. The urodynamic parameters of two groups respectively have significant difference only between the pre- and post-operation of resection of prostate plus distant 2.0cm length urethra, MUP and MUCP(p<0.05), UFL. UCL. UFA and UCA (p<0.01) .2. The weight and urodynamic parameters of male dogs have no significant difference between group C and group D before operation(p>0.05). Two groups respectively between the pre- and post-operation, UFL. UCL. UFA and UCA existed significant deviations in two group(p<0.01), MUP and MUCP existed significant deviations(p<0.05) in group C and have no significant difference(p>0.05) in group D. In comparison with urodynamic parameters of the two groups after operation, MUP. MUCP have no significant difference(p>0.05). UFL. UCL. UFA. UCA and SLPP existed significant deviations(p<0.01). The incidence of post-operative continence, group D is better than group C(p<0.05).Conclusions:1. There was a direct ratio between the length of functional urehra and capability of urine controlling under the circumstance of the extrinsic factors of urethra. The male dogs could appeare incontinence after resection of certain critical length of posterior urethra.2. The shortening of functional urethra after RP may be one of the main reason for incontinence. Reconstruction of functional urethra using anterior bladder flap pedicle myotube is a good choice to treat the urinary incontinence after RP.