To investigate the clinical efficacy of transurethral incision of bladder neck and proximal urethra (TUINU) for the treatment of female primary bladder neck obstruction (PBNO).

This prospective study enrolled 90 female patients with PBNO between July 2022 and December 2023. All patients fulfilled the clinical diagnostic criteria for female bladder outlet obstruction (FBOO) [1], with cystoscopic evidence of either an elevated posterior bladder neck lip or circumferential narrowing associated with pale mucosa. 
The cohort demonstrated the following characteristics: mean age of 55.2±16.7 years, median disease duration of 4.5 (interquartile range [IQR]: 2.0-9.8) years, voided volume of 158.5 (IQR: 100.3-234.0) mL, maximum flow rate (Qmax) of 11.1 (IQR: 7.5-15.3) mL/s, average flow rate (Qave) of 4.3 (IQR: 3.0-7.0) mL/s, postvoid residual (PVR) of 12.0 (IQR: 5.0-50.0) mL, International Prostate Symptom Score (IPSS) of 24.4±5.2, Quality of Life (QoL) score of 5.1±0.6, and Overactive Bladder Symptom Score (OABSS) of 7.1±3.5. 
All patients underwent TUINU. Under laryngeal mask airway general anesthesia, a 30° monopolar resectoscope was transurethrally inserted. Full-thickness incisions were made at the 5-, 7-, 11-, and 1-o’clock positions of the bladder neck and proximal urethra, extending to the perivesical fat layer. The hypertrophic tissue between the 5- and 7-o’clock positions was resected until flush with the trigone. The 12-o’clock mucosal tissue was preserved to prevent urethral roof collapse and urinary stream obstruction. After preserving 2.5 cm of intact distal urethra, an intraoperative Valsalva maneuver was performed: the bladder was filled with 300-400 mL irrigation fluid, and suprapubic pressure of 70-90 cmH2O was applied to assess urinary stream diameter and Qmax. Postoperative follow-up was conducted at 1 and 3 months.

All 90 procedures were successfully completed without intraoperative complications. Intraoperative findings included glomerulations (36 cases), reduced bladder capacity (<300 mL, 8 cases), and enlarged bladder capacity (>500 mL, 6 cases). The median catheterization duration was 5.0 days (IQR: 4.0-7.0). Histopathological analysis revealed chronic inflammation (67 cases), mucosal vascular dilatation and congestion (63 cases), squamous metaplasia (15 cases), glandular cystitis (20 cases), and malacoplakia (1 case).
At 1- and 3-month postoperative follow-ups, the median Qmax was 16.4 mL/s (IQR: 10.9-23.5) and 17.3 mL/s (IQR: 14.3-25.7), respectively, while the Qave was 6.7 mL/s (IQR: 4.3-10.7) and 7.0 mL/s (IQR: 5.9-11.7). PVR decreased to 2.5 mL (IQR: 0.0-10.0). Postoperative symptom scores (IPSS, voiding/storage subscores, QoL, and OABSS) significantly improved at 1 and 3 months compared to preoperative values (all P < 0.001) (Table 1).
Based on IPSS efficacy criteria, symptom control (IPSS score≤7 or symptom reduction rate ≥75%) was achieved in 29 (32.2%) and 63 (70.0%) cases at 1 and 3 months, respectively, with overall effectiveness rates (symptom reduction rate ≥25%) of 84.4% (76/90) and 87.8% (79/90). Postoperative complications included new-onset stress urinary incontinence (SUI) in 7 mild (7.7%) and 1 moderate (1.1%) cases, all of which improved with pelvic floor muscle training. 4 patients (4.4%) required urethral dilation within 3 months. No major complications, such as vesicovaginal fistula, were observed.

TUINU significantly improved lower urinary tract symptoms (LUTS) and urinary flow in female PBNO patients, with marked reductions in IPSS, OABSS, and QoL scores. The low complication rate and sustained efficacy (70% symptom control at 3 months) underscore its clinical viability as a minimally invasive intervention.

TUINU is a safe and effective surgical approach for female PBNO, demonstrating significant improvements in lower urinary tract symptoms (LUTS) and quality of life with a low complication rate. These findings support its clinical application as a viable therapeutic option.

Haylen B T, De Ridder D, Freeman R M, et al. An International Urogynecological Association (IUGA)/International Continence Society (ICS) joint report on the terminology for female pelvic floor dysfunction. International Urogynecology Journal, 2010, 21(1): 5-26.