Wael M Sameh1, Ahmed Abulfotooh Eid. 1. Department of Urology, Faculty of Medicine, University of Alexandria, Alexandria, Egypt. waelsameh@yahoo.com
Abstract
OBJECTIVE: To document, in an in vivo study, the pressure transmission from the urinary bladder to the upper tract through ureteric stents in human patients. Stents have acquired special importance in the urological armamentarium. Flank pain and hydronephrosis are associated with stenting in 50% and 18% of cases, respectively. Pressure transmission from urinary bladder to the upper tract through the stent is the logical explanation for loin pain and hydronephrosis. METHODS: This study was conducted in a prospective manner. We did not select patients or modify their management; instead, we studied patients who, during the course of urological management of some upper tract disease, are left with both a ureteric stent and a nephrostomy tube. Twenty patients fulfilled our criteria. After written consent, a pressure-flow study was done monitoring pressure changes in the renal pelvis during different phases of bladder filling in sitting and recumbent positions. RESULTS: Pressure-flow curves showed almost equal transmission of pressure from the bladder to the renal pelvis throughout all phases of bladder filling and emptying. Any voluntary and involuntary rise of pressure in the bladder was instantly and almost equally transmitted to the renal pelvis. A subgroup of patients with infravesical obstruction resulting from benign prostatic hyperplasia also showed equal transmission of the elevated intravesical pressure during voiding to the renal pelvis. CONCLUSION: Pressure from the lower urinary tract is transmitted to the upper tract through the stent, posing a threat to the renal parenchyma and function. Stent placement, when indicated, should be used for the shortest period possible, in sterile urine.
OBJECTIVE: To document, in an in vivo study, the pressure transmission from the urinary bladder to the upper tract through ureteric stents in humanpatients. Stents have acquired special importance in the urological armamentarium. Flank pain and hydronephrosis are associated with stenting in 50% and 18% of cases, respectively. Pressure transmission from urinary bladder to the upper tract through the stent is the logical explanation for loin pain and hydronephrosis. METHODS: This study was conducted in a prospective manner. We did not select patients or modify their management; instead, we studied patients who, during the course of urological management of some upper tract disease, are left with both a ureteric stent and a nephrostomy tube. Twenty patients fulfilled our criteria. After written consent, a pressure-flow study was done monitoring pressure changes in the renal pelvis during different phases of bladder filling in sitting and recumbent positions. RESULTS: Pressure-flow curves showed almost equal transmission of pressure from the bladder to the renal pelvis throughout all phases of bladder filling and emptying. Any voluntary and involuntary rise of pressure in the bladder was instantly and almost equally transmitted to the renal pelvis. A subgroup of patients with infravesical obstruction resulting from benign prostatic hyperplasia also showed equal transmission of the elevated intravesical pressure during voiding to the renal pelvis. CONCLUSION: Pressure from the lower urinary tract is transmitted to the upper tract through the stent, posing a threat to the renal parenchyma and function. Stent placement, when indicated, should be used for the shortest period possible, in sterile urine.