Hypothesis / aims of study
Until now, there is no satisfactory treatment for patients with underactive bladder (UAB) and chronic urine retention. Clean intermittent catheterization (CIC) 4 to 6 times per day is recommended for these patients. However, many patients find it inconvenient and difficult to achieve.
Consequently, there is a need for better treatments that could reduce the frequency of daily CIC and potentially enable spontaneous voiding. We proposed a novel treatment combining transvaginal ultrasound-guided botulinum toxin A (BoNT-A) injection and transurethral bladder neck incision (TUI-BN) for female underactive bladder with chronic urine retention
Study design, materials and methods
From November 2021 to July 2023, we enrolled 10 women suffering from UAB symptoms, with excess post-void residual (PVR) volumes greater than 300 ml, who underwent CIC. All had experienced urine retention for at least one year and were dissatisfied with previous conventional management, including long-term Foley catheter indwelling, alpha-blocker therapy, and bethanechol therapy. Urodynamic studies demonstrated detrusor underactivity or impaired contractility in all patients.
We assessed the patients using the International Prostate Symptom Score (IPSS), PVR, video urodynamics, and the number of CICs. Data were collected one day prior to the surgical procedure and at one week, one month, and three months post-surgery.
The surgical procedure involved an ultrasound-guided injection of BoNT-A (BOTOX®, Allergan, Irvine, CA, USA) into the external sphincter. Additionally, we performed the TUI-BN procedure by making deep incisions at the 4, 8, and 12 o'clock positions using a Collins knife.
Results
The ages of the patients ranged from 39 to 78 years, with a mean of 64.7 ± 12.8 years. Following surgery, all 10 patients were able to urinate spontaneously. Post-surgery PVR volumes were significantly reduced, measuring 384.5 ± 64.3 ml before surgery and 112.3 ± 77.8 ml, 87.4 ± 56.6 ml, and 79.3 ± 64.6 ml at one week, one month, and three months post-surgery, respectively. Seven out of the 10 patients (70%) no longer required CIC after surgery, while the remaining three needed CIC before bedtime due to a PVR greater than 200 ml and a history of urinary tract infections. Six patients experienced stress urinary incontinence (SUI) postoperatively; for five of them, the symptoms were mild and improved with pelvic floor muscle exercises. A 39-year-old female presented with SUI preoperatively. Her voiding symptoms improved post-surgery with a decreased PVR, but she experienced more pronounced SUI. After three months of conservative treatment, she decided to undergo a retropubic midurethral sling procedure. Postoperatively, her incontinence symptoms improved, with a residual urine volume of approximately 200 cc, requiring catheterization only once before bedtime.
Interpretation of results
Our preliminary study involved 10 patients undergoing this surgery, all of whom regained the ability to void spontaneously. Seven out of the 10 patients (70%) no longer required CIC postoperatively. The patients reported a significant improvement in their quality of life, expressing satisfaction with the treatment due to the reduced need for frequent CIC.
The female external sphincter is notably thin. Macura et al. measured the thickness of the external sphincter using magnetic resonance images from 23 continent volunteers and reported a thickness of 2.06 ± 0.41 mm. In 2023, we proposed and published a new treatment method that utilizes real-time ultrasound guidance to accurately identify the external urethral sphincter, allowing for precise BoNT-A injections into this structure. By employing this new technique to relax the external sphincter and performing a bladder neck incision on the internal sphincter, we successfully enabled patients with UAB to void independently and reduced their residual urine volume.
Postoperative urinary incontinence remains a significant issue. Most patients experienced only mild stress urinary incontinence (SUI) after surgery, which improved with pelvic floor muscle training. However, one 39-year-old patient with preoperative UAB and SUI experienced a reduction in PVR but an exacerbation of SUI postoperatively. This patient underwent a retropubic midurethral sling procedure, which successfully improved the SUI without worsening urinary retention. Our treatment rationale is that the retropubic midurethral sling increases urethral outlet resistance during coughing or increased abdominal pressure, without affecting normal voiding.