Endoscopic Injection (Deflux / Subureteral Bulking) Treatment

Endoscopic injection (subureteral bulking) is performed under general anesthesia using a thin cystoscope passed through the urethra into the bladder; there is no skin incision. The opening where the ureter enters the bladder is visualized, and a bulking agent is injected with a needle just below the opening or within the tunnel itself. The resulting mound reshapes the opening into a slit and allows the ureter to close when the bladder fills — the bulking agent takes over the valve function that the short tunnel could not perform.

• General anesthesia, no skin incision
• Duration about 15–30 minutes
• Same-day: discharged the same day
• Little pain; a simple pain reliever is usually enough if needed
• Follow-up: ultrasound at 4–6 weeks, VCUG or ceVUS at 3–6 months (varies by center)

The most widely used bulking agent is dextranomer/hyaluronic acid copolymer (Dx/HA, brand name Deflux). The hyaluronic acid carrier gel is gradually absorbed over time, while the dextranomer microspheres remain in place, and the body's own connective tissue grows around them, creating a lasting volume. There is more than twenty years of use data, and its safety profile in children is well established.

• Permanent synthetic materials (such as polyacrylate polyalcohol copolymer, Vantris) have reported higher resolution rates, but a more cautious approach is taken because of reports that ureteral obstruction can occur even late after the procedure. The long-term behavior of these materials is still being studied; it is reasonable to ask your team about their reasoning for the choice of material.

Injection success cannot be expressed with a single number — it depends on the grade of reflux, the shape of the ureteral opening, accompanying problems, and experience. The single-session success ranges reported in the literature are approximately as follows; they vary by center.

• Grade I–II: about 80–90%
• Grade III: about 70–75%
• Grade IV: about 60–65%
• Grade V: about 30–50%
• Total with repeat injection: about 85%

Knowing the limits of injection prevents unnecessary repeats and disappointment. In high-grade (IV–V) reflux, where the ureter is markedly dilated and tortuous, single-session success is low; injection can still be attempted in these children, but reimplantation is discussed from the outset.

The procedure is low-risk. A few days of mild burning or a small amount of blood in the urine may occur; febrile infection is rare and its risk is reduced with the single dose of antibiotic given during the procedure. The most important complication is ureteral obstruction; with Dx/HA it is reported in under 1% of cases and is usually temporary, rarely requiring a temporary stent. For this reason, an ultrasound is done 4–6 weeks later to check for any new dilation in the kidney.