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NCT Number: NCT07697677

Modified Mini-PCNL Versus Standard PCNL for Complex Kidney Stones

Kidney stones that are large or complex are often treated with percutaneous nephrolithotomy, also called PCNL. Standard PCNL uses a larger access tract and is effective for removing complex kidney stones, but it may be associated with more bleeding, pain, and recovery burden. Modified mini-PCNL uses a smaller access tract and may reduce surgical trauma while maintaining a similar stone clearance rate.

This multicenter randomized trial will compare modified mini-PCNL using a 20 Fr access sheath with standard PCNL using a 24 Fr access sheath in adults with complex renal stones. About 1,380 participants from 8 urology centers will be randomly assigned to receive one of the two procedures. The main purpose of the study is to determine whether modified mini-PCNL is not worse than standard PCNL in achieving stone-free status shortly after surgery. Stone-free status will be assessed by low-dose noncontrast CT within 72 hours after surgery. The study will also compare stone-free status at 3 months, complications, operation time, length of hospital stay, need for additional procedures, and quality of life.

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Key information

Conditions

Kidney Stones Calculi Complex Renal Calculi Female Urogenital Diseases Female Urogenital Diseases and Pregnancy Complications Kidney Calculi Kidney Diseases Male Urogenital Diseases Nephrolithiasis Pathological Conditions, Anatomical Pathological Conditions, Signs and Symptoms Urinary Calculi Urogenital Diseases Urolithiasis Urologic Diseases

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

The First Affiliated Hospital of Guangzhou Medical University

Guangzhou, Guangdong, 510120, China

Location status: Recruiting

Location contact

Yongda Liu

CONTACT

[email protected]

+020-83062923

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Adults aged ≥18 years.
  • Serum creatinine ≤133 μmol/L.
  • American Society of Anesthesiologists (ASA) physical status classification I-III.
  • S.T.O.N.E. score ≥8.
  • Complex renal stones confirmed by noncontrast computed tomography, including stone surface area >1500 mm², multiple calyceal stones, partial or complete staghorn calculi, or complex anatomical conditions.
  • Patients who provide written informed consent and agree to undergo either modified mini-percutaneous nephrolithotomy or standard percutaneous nephrolithotomy.

Exclusion criteria

  • Solitary kidney.
  • Morbid obesity (body mass index ≥35 kg/m²).
  • Previous renal transplantation or urinary diversion.
  • Congenital abnormalities of the urinary tract.
  • Pregnancy.
  • Uncorrected coagulopathy.
  • Active urinary tract infection.

Treatment and study plan

20 Fr Modified Mini Percutaneous Nephrolithotomy

Procedure

Modified mini percutaneous nephrolithotomy performed with a 20 Fr access sheath and F17 Hawk nephroscope. Stone fragmentation may be performed using pneumatic lithotripsy, Ho:YAG laser, or thulium fiber laser according to the standardized surgical protocol.

Other names: Modified Mini-PCNL, Modified mPNL, 20 Fr Modified Mini-PCNL

24 Fr Standard Percutaneous Nephrolithotomy

Procedure

Standard percutaneous nephrolithotomy performed with a 24 Fr access sheath and F20.8 Wolf nephroscope. Stone fragmentation may be performed using pneumatic lithotripsy, Ho:YAG laser, or thulium fiber laser according to the standardized surgical protocol.

Other names: Standard PCNL, sPNL, 24 Fr Standard PCNL

Primary outcomes

  1. Immediate Stone-Free Rate

    Time frame: Within 72 hours after surgery

    Proportion of participants who achieve stone-free status after surgery. Stone-free status is defined as no residual stone visualized under endoscopy and no residual stone fragments, or residual fragments ≤2 mm, on low-dose noncontrast CT with 2-mm slice thickness.

Secondary outcomes

  1. Stone-Free Rate at 3 Months

    Time frame: 3 months after surgery

    Proportion of participants who achieve stone-free status at 3-month follow-up according to low-dose noncontrast CT.

  2. Length of Hospital Stay

    Time frame: From surgery to hospital discharge, assessed up to 30 days after surgery

    Number of days from the day of surgery to the day of hospital discharge, rounded to the nearest whole day.

Study contacts

Contact information is provided by the study sponsor or research team.

Yongda Liu, Doctor

CONTACT

[email protected]

+020-83062923

Sponsors and collaborators

Lead sponsor

The First Affiliated Hospital of Guangzhou Medical University

Other

Registry information

Official study title

Modified Mini Percutaneous Nephrolithotomy Versus Standard Percutaneous Nephrolithotomy for the Treatment of Complex Renal Calculi: A Multicenter Randomized Controlled Trial

Acronym: MIMIC-PCNL

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Jul 13, 2026
Registry last updated
Jul 13, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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