1. Flow dynamics in a drained ureter: Artificial and computer models
1Haifler M1,2, Weiss D3, Winkler H1, Ramon J1, Einav S 3, Kleinmann N
1 Department of Urology, Chaim Sheba medical center
2 OMNI research group, Department of biomedical engineering, Tel Aviv University
3 Cardiovascular System and Bioengineering Laboratory, Department of biomedical engineering
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Material and methods
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Conclusions

2. Introduction
Ureteral drainage by a double pigtail ureteral stent is used to drain an obstructed upper urinary tract
The stent relieves pain and improves renal function by decreasing renal pelvis pressure
The stent's function is determined mainly by the urine flow field through and alongside it
Intro

3. Introduction
In cases of severe obstruction caused by malignant diseases failure of the drainage is common
In these cases treatment options include drainage by a stiff stent, two stents (tandem drainage) or a nephrostomy tube Tandem ureteral stents for the decompression of malignant and benign obstructive uropathy. J Endourol Oct;27(10): The double-J ureteral stent: in vivo and in vitro flow studies. J Urol Aug;148(2 Pt 1):
The effects of these drainage options on the flow dynamics in the ureter are unknown
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4. Aim
To examine the ureteral flow dynamics of different types of drainage and degrees of obstruction by way of an artificial and a computational model
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5. Material and methods- artificial model
Syringe pump/infusion bag urine production model
Infusion needle and water column – Pressure monitor
Clamp – Obstruction model
26F foley catheter Ureteral model
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6. Material and methods- artificial model
Urine output mechanisms:
Syringe pump – constant flow
Gravitation – variable flow
Drainage devices:
Single soft stent
Tandem soft stents
Single stiff stent
Tandem stiff stents
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7. Material and methods- Computational model
Navier-Stokes flow equations
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8. Material and methods Outcomes: Pressure at simulated renal pelvis
Time to drainage of 30cc
Statistical analysis
ANCOVA
Statistical significance was set at p<0.05
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9. Results – Artificial model
p <0.001
p <0.001
p =0.03
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10. Results – Computer model
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11. Conclusions
The artificial model was found to be in complete agreement with the computer model
Renal drainage with tandem stiff stents provide the lowest pressure level compared with single stiff or tandem soft stents
Maximal renal protection is predicted with this type of drainage according to the models
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12. THANK YOU!
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