Effects of a head-up position on stone retrieval efficiency and intrarenal pressure using a flexible navigable suction access sheath: an in vitro study.

Masahiro Yamazaki, Toru Sugihara, Eiichiro Takaoka, Hidemitsu Furukawa, Hiroshi Kawahira, Tetsuya Fujimura

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Article in Urolithiasis, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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6 authors.

Masahiro YamazakiDepartment of Urology, Japan Community Health care Organization Utsunomiya Hospital, Tochigi, Japan.

Toru SugiharaDepartment of Urology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke City, Tochigi, 329-0498, Japan. sugiharat@jichi.ac.jp.ORCID http://orcid.org/0000-0002-0901-3209

Eiichiro TakaokaDepartment of Urology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke City, Tochigi, 329-0498, Japan.

Hidemitsu FurukawaDepartment of Mechanical Systems Engineering, Graduate School of Science and Engineering, Yamagata University, Yamagata, Japan.

Hiroshi KawahiraMedical Simulation Center, Jichi Medical University, Tochigi, Japan.

Tetsuya FujimuraDepartment of Urology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke City, Tochigi, 329-0498, Japan.

Funding

Japan Society for the Promotion of Science JP21K12161Japan Society for the Promotion of Science JP24K15231

6 · The paper itself

Abstract

Although flexible navigable suction ureteral access sheaths (FANS) combined with head-up positioning has shown promise in retrograde intrarenal surgery, the effects of the head-up position during the stone retrieval phase have yet to be quantified. In this study, we evaluated the effects of a 20° head-up position on stone retrieval time and intrarenal pressure (IRP) using FANS in a kidney phantom model. Using a supramolecular hydrogel kidney phantom, we performed 44 trials (22 paired comparisons). Five artificial stone fragments (2-3 mm) were placed in the renal pelvis and retrieved via suction through an 11/13-Fr FANS under continuous gravity-driven irrigation. Trials alternated between supine (Group A, 0°) and head-up (Group B, + 20°) positions. IRP was measured using a pressure sensor inserted into the upper calyx. The primary outcome was stone retrieval time, whereas mean and peak IRPs were secondary outcomes. All fragments were retrieved by suction alone without the use of a basket. Mean stone retrieval time was significantly shorter in Group B than in Group A (167.4 ± 44.5 vs. 223.0 ± 65.6 s, respectively; mean difference - 55.7 s; 95% confidence interval, - 92.1 to - 19.3; p < 0.01). Mean IRP was significantly lower in Group B (- 1.40 ± 2.34 vs. 0.51 ± 2.70 mmHg; p < 0.01), as was the peak IRP (2.40 ± 2.66 vs. 7.57 ± 3.56 mmHg; p < 0.01). Our findings provide experimental evidence supporting the integration of positional optimization in FANS-assisted retrograde intrarenal surgery.

Indexed as

Kidney CalculiPatient PositioningHumansPressureSuctionIntrarenal pressurePatient positioningRetrograde intrarenal surgeryStone retrievalSuction ureteral access sheath

Identifiers

PMID42406117

DOI10.1007/s00240-026-02024-y

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.