Female voiding dysfunction is caused by poor coordination between the bladder and its outlet, involving various issues such as detrusor underactivity, anatomic abnormalities, and functional bladder outlet obstruction. Common presentations of functional bladder outlet obstruction include bladder neck dysfunction (BND), dysfunctional voiding (DV), and poor relaxation of the pelvic floor muscles (PRPF), which are typically identified through video-urodynamic studies (VUDS). However, accurate diagnosis can be challenging due to the presence of occult DV or PRPF, especially when dominant BND is identified on fluoroscopy. 
Transurethral incision of the bladder neck (TUIBN) is a surgical option for female bladder neck dysfunction when alpha-blockers have proven ineffective[1]. In cases of dysfunctional voiding where medical treatment has not been successful, botulinum toxin injections can be administered at the urethra [2]. However, if a patient diagnosed with bladder neck dysfunction also has occult dysfunctional voiding, transurethral incision of the bladder neck may not provide sufficient benefit, and subsequent urethral botulinum injections may be necessary to improve voiding efficacy.
There is currently insufficient data on the incidence of occult dysfunctional voiding in patients with bladder neck dysfunction, and there is a lack of clinical evidence regarding the concurrent use of transurethral incision of the bladder neck and urethral botulinum injection for such cases in the literature. This study aims to assess potential predictors of occult DV in patients with BND and analyze their postoperative outcomes.

This study involved a chart review of all female patients diagnosed with BND through video-urodynamic studies and underwent TUIBN for bothersome voiding dysfunction. Based on VUDS findings, BND was further categorized into high-pressure BND and low-pressure BND[3]. The study focused on patients who had received alpha-blockers for BND before TUIBN and retrospectively analyzed their response to these medications to identify potential predictors of occult DV. The study also analyzed the change of three uroflowmetry (UFR) examinations (UFR1, pre-operative and pre-alpha blocker; UFR2, pre-operative and post-alpha blocker; and UFR3, post-TUIBN). Additionally, patients underwent postoperative VUDS and received urethral botulinum toxin injection within three months after TUIBN if they exhibited signs of DV and had unsatisfactory voiding outcomes. The chart review also included collecting baseline patient profiles, perioperative complications, and postoperative outcomes.

Between July 2012 and June 2022, a total of 69 patients who received alpha-blockers before undergoing TUIBN were enrolled in this study. Of these patients, 18 (26.1%) were subsequently confirmed to have occult DV after the procedure and required urethral botulinum injection within three months to improve their voiding dysfunction. The baseline characteristics of the patient profiles between the group with occult DV and the group without were not significantly different, as shown in Table 1. 
Table 2 presents the uroflowmetry parameters of the two groups in three different scenarios, namely UFR1 (preoperative and pre-alpha blocker), UFR2 (preoperative and post-alpha blocker), and UFR3 (post-TUIBN). The results indicate no significant differences between the two groups. The regression analysis did not identify any specific predictor among the baseline patient characteristics, parameters in VUDS, or uroflowmetry that significantly predicted the occurrence of occult DV in patients with BND.

Patients with BND and occult DV had a trend towards a higher rate of post-TUIBN dysuria, urinary tract infection, and the need for antibiotics. The voiding efficacy did not respond to TUIBN alone in the presence of occult DV. Therefore, these patients had a higher chance of requiring post-operative self-catheterization or Foley indwelling, as well as a greater need for post-operative medications such as alpha-blockers and muscle relaxants. All eighteen patients with occult DV received urethral botulinum injections within three months after undergoing TUIBN.

The present study found that 26.1% of patients with BND had occult DV. In such cases, TUIBN alone may not be enough to restore spontaneous voiding and may be associated with a higher incidence of postoperative dysuria and UTI. Patients with occult DV usually require subsequent urethral botulinum injections. Further studies are needed to evaluate the effectiveness of concurrent TUIBN and urethral botulinum injection in treating female voiding dysfunction.

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Continence 7S1 (2023) 101003
DOI: 10.1016/j.cont.2023.101003