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Vesicoureteral Reflux

By Philip E. Gleason, MD

Urinary tract infections (UTI's) in children may either be idiopathic or secondary to underlying urinary tract pathology. Approximately 50%of children will, in fact, have anatomic abnormality of the upper or lower urinary tract predisposing to infection. Of these, approximately 50% will demonstrate vesicoureteral reflux. Vesicoureeteral reflux (VUR) in almost all cases represents a congenital anomaly of the ureteral vesical junction (UVJ).

Typically the ureter runs into the bladder in an oblique fashion creating a submucosal ureteral tunnel. A normal UVJ acts as a one-way valve allowing unobstructed flow of urine from the kidney into the bladder, but prevents reflux of urine into the upper urinary tracts with bladder distention or voiding. A typical ureteral tunnel has a tunnel length that is 5 times greater than the diameter of the ureter and provides an effective functional valve mechanism. In reflux, an aberrantly short ureteral tunnel precludes its effective valve function and allows not only antegrade, but also retrograde passage of urine. Thus, VUR becomes pathologic when children are voiding. Instead of the bladder completely emptying, a portion of the bladder urine is refluxed back into the upper urinary tracts. Upon completion of voiding, this urine then drains directly back down into the bladder. This then results in chronic residual urine and urinary stasis. Thus, one of the predominant mechanisms of defense against UTI's is lost. Instead of any bacteria introduced into the bladder being emptied and flushed free from the system with voiding, there is chronic residual urine and bacteria are not evacuated from the bladder, ultimately allowing development of bladder infection. Unfortunately, once a bladder infection is initiated, then infected urine is refluxing back into the kidneys and predisposes to upper UTI with pyelonephritis and possible renal scarring, producing the damaging effects of reflux and UTI's.

Therefore it is felt wise to evaluate any male or female children with UTI to exclude VUR as a predisposing factor. This is technically accomplished with a voiding cystourethrogram (VCUG). He VCUG also allows the severity of the reflux to be monitored, or graded. It is graded on an international reflux scale from 1-5 with 1 being the mildest and 5 being the most severe. The grade of reflux ultimately allows meaningful assessment of the reflux and immediate and long-term prognosis, adding further therapeutic decision-making. Typically grade 1 and 2 reflux have a relatively high chance of spontaneous resolution. Grade 3 is thought to represent an approximately 50% chance of future spontaneous resolution. High-grade reflux, classified as either grade 4 or 5 is thought to have a relatively unlikely chance of spontaneous resolution.

Discussion is then held with the family about potential short and long-term management. Often reflux is managed, at least initially, with medical therapy including antibiotic prophylaxis to help prevent UTI's. Reflux, in and of itself, is typically not thought to produce damaging effects to the kidneys as the mechanism of scarring is thought to be more directly attributable to secondary infection. If infections can be prevented, the reflux can be followed with annual assessment including VCU and renal ultrasound following the course of the reflux and renal growth respectively. Antibiotic therapy is typically directed along usage of Septra, Nitrofurantoin, or Amoxicillin, etc. These antibiotics are typically safe for long-term use and the benefits of antibiotic prophylaxis outweigh the risks off side effects. If the reflux resolves spontaneously, then the children can be taken off antibiotic prophylaxis and followed conservatively. While they will still have normal male or female population risk of UTI's, their increased risk will be normalized.

If reflux doesn't resolve spontaneously or if there are ongoing difficulties with breakthrough UTI's even despite antibiotic prophylaxis, then consideration is given to surgical therapy. This is accomplished by ureteral reimplantation which is a moderate surgical procedure requiring 2-3 days of hospitalization. The length of reflux follow up to determine if the reflux will resolve spontaneously is somewhat controversial. In the past, many children have been followed through childhood to near pubertal ages. There is some new information from a 1992 large, combined United States and European prospective randomized reflux study now that says that if reflux doesn't resolve by approximately age 5, then the chances of subsequent resolution are significantly diminished. Many authors are now therefore advocating earlier surgical reimplantation for high-grade reflux and for failure of spontaneous resolution of reflux by school age.

In summary, VUR may be a common source of urinary tract pathology including infections and reflux nephropathy. Early diagnosis and careful management by either medical or surgical regimens can, however, significantly minimize morbidity in the children and prevent future long-term sequelae.