Female voiding dysfunction is frequently encountered in urological practice due to neurogenic or non-neurogenic etiologies, including DU, BNO, or unknown causes.12 Although CIC is the standard treatment option, patients usually wish to void spontaneously without the need of a catheter, in order to have a better life quality. This study demonstrated TUI-BN alone or in combination with additional procedure was safe, effective, and long-term durable in 62.7% of women. Patients with DU benefit most in resuming spontaneous voiding.
DU exists among elderly resulting in chronic urinary retention, recurrent urinary tract infection, deteriorating of renal function and long-term catheterization, which affected life quality. Up to now, there is limited effective pharmacotherapy and lack of consensus in treating DU patients.13 TUI-BN has a promising high success rate 74.6% to resume spontaneous voiding in DU patients and our promising effect was similar to previous studies.9,14 An adequate incision of the bladder neck smooth muscle until the serosa is crucial for a successful surgical outcome.
A wide-open bladder neck under cystoscopy; and funnel shape of the bladder neck opening during voiding phase effectively reduces the resistance of bladder outlet. In the premise of adequate abdominal pressure, TUI-BN may facilitate spontaneous voiding in DU patients by abdominal straining resulting in increased VE and reduced PVR. Interestingly, this study revealed a dramatic improvement in Qmax by 413.3%, Vol. by 346.7%, cQmax by 369.2%, BCI by 122.8%, and PVR by 68.7% in the success group after treatment. TUI-BN alone or combining additional surgery provided a promising surgical outcome in patients with DU. Therefore, TUI-BN might be considered as a standard therapy for DU patient if medical treatment failed and patients desired a spontaneous voiding without CIC.
Based on the analysis of urodynamic parameters, the study revealed a higher PVR and a lower voided volume at baseline are the predictive factors for a successful surgical outcome. Bladder neck plays a crucial role in voiding phase. High sympathetic tone of the bladder neck might lead to negative feedback that inhibited the detrusor contractility during voiding phase. 15 In this study, the BCI improved by 122.8% once TUI-BN was performed. The previous study revealed an open bladder neck on voiding cystourethrography is the only predictive factor for successful urethral sphincter onabotulinumtoxinA injection in patients with voiding dysfunction regardless neurogenic or non-neurogenic based.16,17 Once the bladder neck was opened widely by TUI-BN with or without additional TUI-BN, TUI-ES, or urethral sphincter onabotulinumtoxin A injection could subsequently provide a promising surgical outcome with additional success rate of 64.7% in those who failed the first TUI-BN.
A closed bladder neck and urethral opening were usually noted during voiding phase in DU patient with or without neuropathy in VUDS. It is a challenge to distinguish between the association of inadequate detrusor contractility, bladder neck dysfunction or tight urethral external sphincter especially in DU patients during VUDS. Sympathetic nerve mediated by adrenergic alpha-receptors extends from the bladder neck and prostate to the external urethral sphincter in male.18 Pudendal nerve stimulation evoked somatic responses in the external urethral sphincter and increased bladder neck pressure.19 In this study, the success rate for TUI-BN alone particularly in DU patients was only 30.5%, however, the success rate can be achieved to 76.5% with the combination of additional surgery such as repeat TUI-BN, urethral sphincter onabotulinumtoxin A injection or TUI-ES. Therefore, in patients who failed the initial TUI-BN, a precise post-operative VUDS was mandatory and additional surgery was essential in order to resume spontaneous voiding.
In this study, 90.4% of patients with neurogenic bladder had the diagnosis of DU. Population with neurogenic bladder were younger in age, mostly due to post-pelvic surgery. Therefore, the patients usually had a stronger abdominal pressure while voiding. The reduction of bladder neck resistance by TUI-BN and additional surgery enables spontaneous voiding in neurogenic bladder patients, with VE improved up to 50%. On the other hand, most of the patients with non-neurogenic bladder were lack of abdominal straining ability, as they were frail and associated with multiple underline comorbidity
Patients with hypersensitive bladder had the lowest success rate of 22.2%. In previous study, bladder pain causing bladder outlet dysfunction, and one third of the patients was found to have functional obstruction at the external sphincter. Chronic inflammation of the bladder might result in external sphincter hyperactivity while voiding.20 Visceral pain syndromes might associate with central and peripheral sensitization and lowering of nociceptive threshold, resulting in neuropathic upregulation, hypersensitivity, allodynia and dysfunctional voiding.21 Increased pudendal afferent activity through the guarding reflex of the external urethral sphincter, and thus inhibited the efficiency of bladder contractility.22 The ongoing chronic inflammation sustained the external sphincter spasticity addition to inhibition of bladder contractility, lead to less satisfactory surgical outcome despite undergoing TUI-BN or additional surgery.
The adverse event of TUI-BN and additional surgery was limited and confined to certain population. Among the four patients who developed vesicovaginal fistula, 3 of the patients underwent TUI-BN twice and one of them underwent additional TUI-ES twice. Interestingly, all of them associated with de novo incontinence and underwent suburethral sling surgery latterly and 2 of them underwent additional urethral sphincter PRP injection. Autologous PRP is rich in growth factors and cytokines, which regulate tissue reconstruction that augments wound healing, speed the recovery from muscle and joint injuries, and enhance recovery after surgical repair.23 PRP was injected at the urethral external sphincter in order to increase urethral resistance. 24 Currently, three patients resumed spontaneous voiding and another one was under self-voiding and CISC. The confined patients underwent multiple repeated surgeries and complication recovery surgery mainly due to unhealthy localized tissue and repeated surgeries caused tissue adhesion. Besides, 12 patients were reported underwent suburethral sling surgery due to de novo incontinence after TUI-BN. All of them had recovered from stress urinary incontinence, 8 patients were under self-voiding, 3 patients under CISC with self-voiding, and another patient under CISC.
The limitation of this study is by its retrospective designs and single-center experience. A prospective study should be designed to validate the effectiveness of TUI-BN in female with voiding dysfunction and a tight bladder neck.