MP15-03: Nephrostomy Tubes Placed Prior to Percutaneous Renal Stone Surgery Are Practical for Obtaining Access-- An Analysis of the Utility of Pre-Existing Nephrostomy Tubes at a Single Institution

Aaron Bradshaw, Seth Bechis, Kaitlan Cobb, Dave Friedlander, Roger Sur

Introduction: Renal access in percutaneous nephrolithotomy may be obtained via a pre-existing nephrostomy tube (NT) tract; however, emergently placed NTs are not always ideal for subsequent surgery. We sought to compare the usability of emergently and non-emergently placed NTs.

Methods: A retrospective review was performed of UC San Diego subjects undergoing percutaneous renal surgery between January 2016 and October 2018. Demographics and peri-operative variables were collected. The primary outcome was the usability of NT tract for dilation and instrumentation and was a composite of “usable” and “partially usable” tracts. “Usable” indicated a tract in which PCNL could be completed without the need for additional tract creation; “partially usable” indicated a tract which was dilated and used but required at least one additional tract dilation, and “unusable” indicated the absence of tract dilation or usage.

Results: 65 PCNL cases had previously placed indwelling NT at time of percutaneous renal surgery (35 emergent, 30 non-emergent). Demographic and peri-operative data were similar. There was no significant difference between emergent vs. non-emergent groups in tract usability (emergent 51% vs. non-emergent 63% usable, difference in proportions 95% CI, -13% to 37%, p=0.34), location of NTs (p=0.29), or location of ultimate PCNL access (p=0.86). Total number of access tracts was greater in the cohort with unusable NT tracts (p<0.01). The need for subsequent upper pole access for completion of PCNL occurred in 57% of unusable NT tracts, 33% of partially usable NT tracts, and 6% of usable of NT tracts (p<0.01). There was no difference in stone location between those NT tracts deemed usable, partially usable, or unusable (p=0.40)

Conclusions: Pre-existing NT, regardless of indication for placement, served as sufficient PCNL access tracts in over half of recorded cases. Contrary to recently published reports, the utility of pre-existing NT appears to vary among health systems. Other variables, including the desired location of PCNL appear to directly influence the likelihood of NT tract usability. Source of

Funding: None