Reflux nephropathy in transplants

Abstract

Reflux nephropathy, renal scarring after urine infection, typically occurs in infancy. Although vesicoureteric reflux occurs commonly in kidney allografts, grafts have not previously been regarded as likely to be affected by reflux nephropathy, perhaps because older kidneys are considered to have matured out of the risk. Evidence that adult pigs remain at risk of reflux nephropathy challenges that assumption. We therefore reviewed the pathological findings in allograft nephrectomy specimens to look for evidence of reflux nephropathy, and sought evidence of focal transplant renal scarring in paediatric recipients who had a urine infection and vesicoureteric reflux. Consecutive allograft nephrectomy specimens (146) that had been removed between 1990 and 1999 were examined for evidence of reflux nephropathy, and relevant case notes were reviewed. Also, children with a renal transplant who had a urine infection were investigated for focal scarring by dimercaptosuccinic acid (DMSA) scanning and for reflux with a cystogram. Four transplanted kidneys from adult donors that were removed from adult recipients had developed changes consistent with reflux nephropathy. Of these, 3 also had definite evidence and 1 probable evidence of a glomerulopathy associated with hyperfiltration due to reduced renal mass. All 4 patients had had recurrent urine infection and the 2 assessed had had vesicoureteric reflux. Two children with renal transplants that also had urine infections and vesicoureteric reflux to their graft were shown to have sustained focal damage on DMSA scan, confirmed as reflux nephropathy scarring on biopsy in 1 case. The grafts were aged 14.4 years and over 16 years at the time of scarring. Reflux nephropathy can occur in previously healthy adult human kidneys after transplantation. Previous studies of the effect of vesicoureteric reflux on renal allografts were not designed to assess the possibility of mild or focal scarring.

Is reflux nephropathy preventable, and will the NICE childhood UTI guidelines help?

“…Young children’s kidneys are seldom used for transplantation, so reflux nephropathy was not expected to occur. However, scars with typical pyelonephritic histology have been reported in transplant nephrectomies,23 and shown to be very common, and often severe, on DMSA (despite never being recognised on ultrasound) 24. This appears to conform closely to Ransley and Risdon’s model for native kidneys,4 with about 70% of transplants with VUR acquiring focal scars after a UTI.…”

Vesicoureteral Reflux and Reflux Nephropathy

“…However, scarring does occur in adult kidneys as well. Adult pig kidneys scar as quickly as those of piglets with VUR and UTI 25 and scarring is known to occur in adult mature kidneys transplanted into pediatric patients 26 . Some recent studies have reported that the age may not be a risk factor for renal scarring and the risk in older children is the same 21, 27, 28 or even higher 29, 30 as compared to the younger children.…”

Urinary tract infections in children after renal transplantation

“…Also, after KTX, UTI may lead to kidney damage, negatively affecting long-term graft survival by scarring and interstitial injury [5–7], although precise data for the pediatric population are scarce [8–10]. UTI management in such patients undoubtedly is more complex compared with UTI in otherwise healthy children, so that extrapolation of data is not always possible.…”