Urology mythbusters: The 5:1 ratio in ureteral reimplantation

Kurtz, Michael P.

doi:10.1016/j.jpurol.2017.03.004

Cited by 3 publications

(1 citation statement)

References 11 publications

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“…And if we extrapolate from the rest state, a 5:1 length-todiameter ratio at rest (10%V c ) results in a ratio of 3:1 at 80%V c . This supports the high success rate of antireflux 18,19 and continent catheterizable channel surgery as we are probably over engineering the reflux mechanism that is attributed to the length-to-diameter ratio.…”

Section: Discussionsupporting

confidence: 73%

The 5:1 rule overestimates the needed tunnel length during ureteral reimplantation

Kalayeh

Fowlkes

Schultz

et al. 2020

Neurourology and Urodynamics

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Aims: Paquin asserts that in order for ureterovesical junctions (UVJs) to prevent reflux, the ureteral tunnel length-to-diameter ratio needs to be 5:1. We hypothesize that the surgical implementation of this observation results in an overestimation of the needed length-to-diameter ratio to prevent vesicoureteral reflux. Methods: With finite elements, we model the urine storage phase of the bladder under nonlinear conditions. In the reference state, the bladder is assumed to be a sphere with an oblique straight elliptical hole as the UVJ. Broad parametric studies on different length-to-diameter ratios are performed as the bladder volume increases from 10% to 110% capacity. Results: The capability of the UVJ to prevent reflux during storage depends on its length-to-diameter ratio. UVJs with larger length-to-diameter ratios lengthen and narrow as the bladder volume increases, causing the closure of the UVJ and rise in its flow resistance. Our model shows that the UVJ length-to-diameter ratio decreases as the bladder volume increases. The 5:1 ratio implemented at 80% capacity-approximate volume or bladder wall stretch during ureteroneocystostomy (UNC)-corresponds to 7:1 at the reference state-used by Paquin. The 5:1 ratio implemented at the reference state corresponds to 3:1 at 80% capacity. Conclusions: Our modeling results are consistent with Paquin's original observation on the significance of the UVJ length-to-diameter ratio in preventing reflux. They, however, indicate that the surgical implementation of this rule during UNC results in an overestimation of the requisite tunnel length-todiameter ratio to prevent reflux. They also suggest that the UVJ closure is due to the bladder wall deformation rather than the pressure.

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Section: Discussionsupporting

confidence: 73%