The impact of reflux pressure on renal scarring in children with sterile vesicoureteral reflux

Abstract

Introduction: Vesicoureteral reflux (VUR) is a complex disease as patient spectrum is variable. Some cases struggle with recurrent febrile urinary tract infections (UTI) and end-up with renal scars despite intervention. While others suffer no clinical problems and need no treatment. The detrimental effect of VUR on kidneys depends on many factors like grade of reflux, detrusor pressure, and presence of voiding dysfunction. The adverse effects of sterile VUR on kidneys is still under discussion. Thus, we assessed the impact of detrusor pressure at VUR onset on renal scarring in children with sterile reflux.

Materials and methods: We retrospectively reviewed the five years follow-up data of 38 children who had unilateral VUR without UTI under treatment. No febrile or afebrile UTIs were detected during the follow-up in any children. All children were assessed with annual video-urodynamics and renal scintigraphy for five consecutive years. The detrusor pressure at VUR onset, grade of VUR, presence of involuntary detrusor contractions, bladder capacity and the presence of renal scaring were recorded. All VURs were recorded during the voiding phase and children with VUR during the filling phase were excluded from the study.

Results: In the first line of video-urodynamic studies, the mean detrusor pressure at VUR onset was 24.3 ± 14.8 cm/H₂O (median 34.5 cm/H₂O, min: 6 - max: 47). There was no relation between boys and girls regarding median detrusor pressure at VUR onset (p = 0.356). Eventually, 22 (57.9%) children developed renal scars and ended up with surgery. There was no relation between scar development and age at first presentation (p = 0.888) The cut-off value for detrusor pressure at VUR onset was noted as 26 cm/H₂O (AUC: 0.849 [p < 0.01], Figure). In children who developed renal scars eventually, the median detrusor pressure at VUR onset was significantly higher (p < 0.01).

Discussion: The detrimental effect of VUR on kidneys is associated with recurrent infections, bladder dysfunction, and detrusor pressure. Dispute over risk of renal scarring in patients with sterile VUR still continues.

Conclusion: Children in whom VUR start at higher voiding pressures suffer more renal scars. The threshold of voiding detrusor pressure for risky patients is identified as 26 cm/H₂O. It is true that patients suffering recurrent febrile UTIs have higher risk of developing renal scarring. However, the impact of sterile reflux should not be underestimated, since renal scars due to sterile reflux may develop in patients under antibiotic prophylaxis.

Keywords: Antibiotic prophylaxis; Follow-up studies; Kidney; Urinary tract infections; Vesico-ureteral reflux.