A Feasibility Study on a Digital Disposable Semirigid Nephroscope for Suction Mini-Percutaneous Nephrolithotripsy

96% intraoperative stone clearance in a 22-min median op time—one author is a paid consultant for the device maker.

Journal: World Journal of Urology | Published: 2026-04-11 | Type: Prospective feasibility study | PMID: 41964872 Authors: Gauhar Vineet (Ng Teng Fong Hospital, Singapore); Kalathia Jaisukh (Fortune Urology Clinic, India); Fong Khi Yung (Singapore General Hospital); Yuen Steffi Kar Kei, Somani Bhaskar, Castellani Daniele (EAU Section of Endourology) Funding/COI: Funding not listed. Kalathia Jaisukh is a paid consultant for Redpine Medical—the manufacturer of the Redpine™ device under evaluation. All other authors declare no conflicts.

Summary

This prospective single-center study put a new digital disposable semirigid nephroscope (Redpine™) through its paces across 328 patients undergoing suction mini-percutaneous nephrolithotomy (SM-PCNL) for renal stones between March 2024 and March 2025. The device pulled double duty as both cystoscope and nephroscope, and surgeons rated it highly on satisfaction scales. Results look clean on paper, but a paid consulting relationship between an author and the device manufacturer hangs over every finding.

Claims

• Median stone diameter: 1.7 cm (IQR 1.3–2.3)
• Median lithotripsy time: 8 min (IQR 5–16); median total operative time: 22 min (IQR 20–35)
• Intraoperative stone-free rate (SFR): 96%
• 30-day SFR: 100% — but defined as Grade A (no fragments, 47.9%, n=157) or Grade B (fragments ≤4 mm, 52.1%, n=171)
• Major complications (Clavien-Dindo ≥3): 0.9% (n=3), including colonic injury, pleural injury, and sepsis; one additional case of arteriovenous fistula requiring angioembolization
• Surgeon satisfaction: median Likert score 1/5 (scale where 1 = excellent) for vision, ease of use, and maneuverability
• Scope tip damage: 0.6% (n=2)
• Reintervention with ESWL within 3 months: 1.2% (n=4)

Study Quality

This is a prospective feasibility study—not a randomized controlled trial, not a comparative study. There is no control arm, no blinding, and no comparison to a reusable digital or fiber-optic nephroscope. The study captures whether the device works at all, not whether it works better, worse, or at comparable cost to existing instruments. That's an appropriate scope for a feasibility study, but the authors' language ("excellent feasibility and safety," "superior surgeon ergonomics") gets ahead of what a single-arm study can actually establish.

The 30-day "100% stone-free rate" headline is arithmetic sleight of hand. Only 47.9% of patients had zero fragments at 30 days. The other 52.1% had fragments ≤4 mm, which are classified as Grade B stone-free per the Delphi consensus definition—a contested threshold that some argue clinically underestimates residual burden. Reporting "100% SFR" without immediately qualifying this definition misleads on first read.

Red Flags

• Financial conflict of interest: Kalathia Jaisukh, a listed author, is a Redpine Medical consultant. Redpine Medical makes the device being evaluated. This is a textbook industry-entangled feasibility study.
• No comparator arm: There is no reusable-scope control group. Operative times and SFR cannot be attributed to the new device versus surgeon skill or patient selection.
• Funding not disclosed: No funding source is listed. For a study of a novel commercial device with a consultant author, this is an omission that should have triggered editorial scrutiny.
• 100% SFR framing: Headline stone-free rate includes fragments ≤4 mm; only 47.9% were truly fragment-free. The abstract buries this.
• Full-text section mismatch: The provided full-text Methods and Results sections appear to be from an entirely different paper—a narrative review of mini-PCNL literature using PubMed/Web of Science database searches. This is either a data-extraction error or a publication integrity concern worth flagging.
• Single center (with contradictory language): The abstract calls this a "single center study" but also says procedures were performed "across institutions." This inconsistency is unexplained.
• Surgeon satisfaction is self-reported by the surgeons using the device: No independent ergonomic assessment.

Strengths

• Reasonable sample size for a feasibility study (n=328)
• Prospective design with predefined inclusion criteria
• Complication classification via validated Clavien-Dindo system
• SFR assessed by low-dose CT at 30 days, not self-report or plain film
• Dual-function scope design (cystoscope + nephroscope) tested systematically across prone and supine approaches

Verdict

A 328-patient prospective feasibility study showing a disposable nephroscope can perform SM-PCNL with reasonable speed and low major complication rates is modestly useful data. The device appears functional. But this paper cannot tell you whether it's better than what urologists already use, because it never tested that question. The consultant-author conflict of interest, undisclosed funding, inflated SFR headline, and apparent full-text section mix-up collectively undermine confidence in the reporting. Treat this as hypothesis-generating industry-adjacent data, not evidence of superiority.