In vitro comparison of prototype magnetic tool with conventional nitinol basket for ureteroscopic retrieval of stone fragments rendered paramagnetic with iron oxide microparticles

Yung K. Tan, Stacey L. McLeroy, Stephen Faddegon, Ephrem Olweny, Raul Fernandez, Heather Beardsley, Bruce Gnade, Samuel Park, Margaret S Pearle, Jeffrey A Cadeddu

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Purpose: We developed a prototype magnetic tool for ureteroscopic extraction of magnetized stone particles. We compared its efficiency for retrieving magnetized calcium oxalate monohydrate stone particles with that of a conventional nitinol basket from the pelvi-collecting system of a bench top ureteroscopic simulator. Materials and Methods: Iron oxide microparticles were successfully bound to 1 to 1.5, 1.5 to 2 and 2 to 2.5 mm human calcium oxalate monohydrate stones. Several coated fragments of each size were implanted in the collecting system of a bench top ureteroscopic simulator. Five-minute timed stone extraction trials were performed for each fragment size using a back loaded 8Fr magnetic tool mounted on a 0.038-inch guidewire or a conventional basket. The median number of fragments retrieved per timed trial was compared for the magnetic tool vs the basket using the Mann-Whitney U test. Results: For 1 to 1.5 mm fragments the median number retrieved within 5 minutes was significantly higher for the prototype magnetic tool than for the nitinol basket (9.5 vs 3.5, p = 0.03). For 1.5 to 2 mm fragments the magnetic tool was more efficient but the difference in the number of fragments retrieved was not statistically significant (9.5 vs 4.5, p = 0.19). For 2 to 2.5 mm fragments there was no difference between the instruments in the number retrieved (6 per group, p = 1.0). Conclusions: The prototype magnetic tool improved the efficiency of retrieving stone particles rendered paramagnetic that were less than 2 mm but showed no advantage for larger fragments. This system has the potential to decrease the number of small retained fragments after ureteroscopic lithotripsy.

Original languageEnglish (US)
Pages (from-to)648-652
Number of pages5
JournalJournal of Urology
Volume188
Issue number2
DOIs
StatePublished - Aug 1 2012

Keywords

  • calcium oxalate
  • endoscopy
  • instrumentation
  • magnetics
  • urinary calculi

ASJC Scopus subject areas

  • Urology

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