Does intraoperative success predict outcome in the treatment of urethral sphincter insufficiency with bulking agent?

Sphincter insufficiency is mostly associated with neurogenic and some structural abnormalities in the pediatric population. As a mini-invasive treatment, urethral bulking agents have been used to treat this problem.

The aim was to evaluate if technical success, defined as intraoperative increase in abdominal leak point pressure (ALPP), predicts the outcome of the treatment of sphincter insufficiency with urethral bulking agent.

We reviewed all children treated first time with dextranomer/hyaluronic acid (Dx/HA) copolymer (Deflux) for urethral sphincter insufficiency and who intraoperatively had ALPPs measured during 2004-2014. Patient characteristics, change in urinary continence and the duration of the possible response were evaluated in neurogenic and non-neurogenic cases.

The median age of the patients was 7.8 years (range 4.1-14.5) at initial treatment and median volume of Dx/HA instilled was 3.5 mL (IQR 2-5). Twelve patients had neurogenic disease and 15 had non-neurogenic disease. Median ALPPs before and after the injections were 19 cmH₂O (IQR 14-28) and 70 cmH₂O (IQR 48-80), p < 0.001. Increases in ALPPs were similar in both patient groups (p = 0.661) and in 17 patients with any response and 10 patients with no response (p = 0.267). In patients with any response the median duration of the response was only 0.8 years (IQR 0.09-2.0). During a median follow-up of 4.9 years (range 1.7-11.8), 15 patients received one to three repeat injections and eight patients went through sling or bladder neck operation (Summary table). During repeat injections, the preoperative ALPPs had returned to the original levels. Currently, 20% are continent or almost continent with one or more Dx/HA injections. In half of the patients with neurogenic bladder, compliance or volume deteriorated slightly in follow-up. Five out of 15 patients who reached puberty become continent spontaneously after failed bladder neck injection.

Intraoperative ALPPs increased significantly in most patients during the procedure. However, only 52% of the patients experienced more than 1 month of success after the procedure, and even in those the effect lasted mostly under a year. With one to four injections one-fifth seem to have had a good long-term result. Although the long-term success rate is limited, bulking agent injection allowed the patients with spontaneous voiding to continue it and the injection did not prevent future treatments.

Intraoperative increased ALPP does not predict a good long-term outcome after Dx/HA injection. At the end, only a fifth of our patients had good result with one or more Dx/HA injections. A change in bladder behavior is possible after treatment.