Where should bulking agents for female urodynamic stress incontinence be injected?

For bulking agents used for female stress urinary incontinence, the recommendation for the anatomical placement varies as some injectables are to be placed close to the bladder neck and others midurethrally. Aim of the study was to determine if there are differences concerning the outcome after transurethral collagen injections depending on the anatomical placement midurethrally or at the bladder neck. We randomly assigned 30 elderly female patients with urodynamic stress incontinence to either transurethral collagen injection midurethrally or to the bladder neck. Prior to injection and at ten month follow-up, maximum urethral closure pressure (MUCP), functional urethral length (FUL), maximum flow rate and cough test were performed and the patient was asked to estimate her bladder condition using a visual analogue scale. Postoperative contentness was 8 (median, 95% confidence interval 5-9) in the midurethral group and 8 (median, 95% confidence interval 7-10) in the bladder neck group with a p value of 0.012, 95% confidence interval -2.464 to -0.2859, in favour to midurethral injections. MUCP and FUL increased significantly in both groups and flow rate decreased in both groups. Continence was 66.6% in the midurethral group and 60% for the bladder neck group respectively. Both midurethral and bladder neck collagen injections improve patients' satisfaction almost equally with a small advantage for midurethral injections.