Presented by: Heiko Yang MD, PhD
UCSF

Introduction

The practice of performing totally tubeless percutaneous nephrolithotomy has been demonstrated to be feasible and safe, especially when smaller access diameters are used (mini-PCNL). Having an objective test to guide patient selection could improve confidence and enable broader adoption of this practice. The purpose of this study was to evaluate the utility of an intraoperative methylene blue test to predict candidacy for a totally tubeless procedure.

Materials

We performed a pilot study in adult patients undergoing mini-PCNL at our institution (enrollment began in May 2023 and is ongoing). Patients with anatomic abnormalities or a history of reconstructive surgery (e.g. strictures, ileal conduits), and cases requiring a ureteral access sheath were excluded. After stone clearance, 10 mL methylene blue dye was injected into the percutaneous access tract. A positive test was defined as visualization of blue dye in the bladder catheter within 1 minute of injection. In the case of a positive test, no upper tract drainage tubes (ureteral stent or nephrostomy tube) were inserted. Post-operative obstructive complications (flank pain, nausea, vomiting, fever) were evaluated as the primary outcome.

Results

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The intraoperative methylene blue test was performed in 5 mini-PCNL cases. Median stone size was 2.2 cm, and the median operative time was 93 minutes. All 5 had positive tests and received no postoperative drainage tubes. Four of 5 patients were discharged same day, while one patient was a planned overnight admission. There were no obstructive or infectious complications on follow-up.

Conclusion

An intraoperative methylene blue test could be a simple and cost-effective way to predict candidacy for totally tubeless mini-PCNL. We are currently increasing the sample size for this study to produce more robust results.

Funding

None

Co-Authors

Wilson Sui, MD
UCSF

Justin Ahn, MD
UCSF

David Bayne, MD
UCSF

Marshall Stoller, MD
UCSF

Thomas Chi, MD
UCSF