To evaluate the outcome, clinical efficacy and patient satisfaction of periurethral bulking as a treatment for stress urinary incontinence.

A retrospective review of all patients having undergone periurethral bulking procedures at a single institution between January 2014 and January 2019 was undertaken. Variables examined included patient’s age, body max index (BMI), previous incontinence procedures, the presence of pre-operative detrusor overactivity (DO), mixed or purely stress urinary incontinence (SUI) and ICIQ-UISF (urinary incontinence short form) scores. Patient outcomes were noted at baseline, first-follow up after treatment and at latest-follow up. Bulkamid injections were carried out using the standard urethroscope and a 3 or 4-point injection technique.

A total of 54 patients were identified to have had a periurethral bulking procedure during this 5 year period by 3 Urological surgeons specialising in female Urology, with a mean first follow-up of 3.6 months (1 month – 11 months) and mean latest-follow up of 18 months (3 months – 5 years). 3 patients were injected with macroplastique and the 51 other patients had Bulkamid injected. 13 (24%) patients had previously undergone anti-incontinence procedures prior to their periurethral bulking. Mean age of patients was 58 years and mean BMI was 29.5. SUI was demonstrated on urodynamics (CMG) in 37 (69%) patients, whilst DO was seen in 9 (17%) patients. The majority of those with DO had mixed urinary incontinence as they had demonstrable SUI on CMG as well. Overall, mean pre-operative pad use was 3.6 pads per 24 hours and mean UISF score was 14.8. 
At first follow-up, 22 patients (40.7%) of our cohort had a successful outcome, classified as one or less pad use, and the mean pad use was 1.5 pads per 24 hours. 
The improvement in the mean UISF score at latest-follow up was a reduction by 4.9 points, to 9.9. 28 (71%) felt the duration of effect from periurethral bulking was between < 1 month and 6 months, with 5 (10%) patients reporting benefit beyond 6 months (See Table 1).
Across our cohort, the mean Likert scale for patient satisfaction with the procedure was 1 on a scale -3 (completely dissatisfied) to +3 (completely satisfied).
Subgroup analysis showed a trend for those with a higher BMI to be less likely to be dry at the first-follow up with 38%, 33% and 20% being dry in BMI groups of normal (n=13), overweight (n=12) and class I obesity (n=16), respectively. Those with a BMI > 40 (n=2) were 100% wet. The 17 patients with no demonstrable SUI on CMG, but reported SUI as a symptom requiring pad use, had a trend to be more likely to be dry at the first-follow up (43.8%) compared to those with CMG demonstrable SUI (38.9%). However, those with urodynamically proven SUI had a greater improvement in their UISF score and greater reduction in pad use post operatively. 
Of the 13 patients (24%) who had undergone previous anti-SUI procedures (transvaginal tape insertion (n=8), previous periurethral injections (n=4), colposuspension (n=1)), 46.2% were dry at first-follow up, compared to the 38.5% in the group with no previous continence procedures. Likert score did not differ significantly between the groups.
10 patients (19%) went on to have further anti-SUI treatment; 5 patients who went on to have a second periurethral bulking procedure, 4 patients went on to have a transvaginal tape insertion and 1 had colposuspension for recurrent SUI.
Within our cohort, pre-operative predictive factors that showed a trend to determining success at first-follow-up included a lower BMI, a lower number of pre-operative pad use, and lack of SUI on urodynamics (See Table 2).
The complication rate was low, with 1.9% risk of urinary tract infection. There were no other recorded adverse events.

The retrospective study provides medium term outcomes following periurethral bulking injection for SUI, with mean latest follow-up of 18 months. Within our cohort of patients, there were improvements noted in the mean UISF score and pad use following periurethral bulking procedure. The duration of effect was short-lived in most cases (< 6 months), with 3 patients (5.6%) reporting effect lasting beyond 6 months.  Patients self-reported the procedure to be satisfactory with a mean Likert score of 1. Factors determining post-operative success may include a lower BMI and lower pad use.

Whilst controversy remains around transurethral synthetic tapes and the recent suspension of its use in the UK, periurethral bulking has become an increasingly popular treatment choice for SUI. This study demonstrated that periurethral bulking has been safe and acceptable as a treatment to patients. It has been limited by its duration of effect in this cohort. Periurethral bulking has a minor adverse effect profile and has a minimally invasive mode of delivery. We would advocate larger, prospective studies to further evaluate aspects of this treatment including injection technique to address treatment durability.