Modified Mini-PCNL Versus Standard PCNL for Complex Kidney Stones (MIMIC-PCNL)

July 7, 2026 updated by: Yongda Liu, The First Affiliated Hospital of Guangzhou Medical University

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

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.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

1380

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • China
    • Guangdong
      • Guangzhou, Guangdong, China, 510120
        • Recruiting
        • The First Affiliated Hospital of Guangzhou Medical University
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Adults aged ≥18 years.
  2. Serum creatinine ≤133 μmol/L.
  3. American Society of Anesthesiologists (ASA) physical status classification I-III.
  4. S.T.O.N.E. score ≥8.
  5. 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.
  6. Patients who provide written informed consent and agree to undergo either modified mini-percutaneous nephrolithotomy or standard percutaneous nephrolithotomy.

Exclusion Criteria:

  1. Solitary kidney.
  2. Morbid obesity (body mass index ≥35 kg/m²).
  3. Previous renal transplantation or urinary diversion.
  4. Congenital abnormalities of the urinary tract.
  5. Pregnancy.
  6. Uncorrected coagulopathy.
  7. Active urinary tract infection.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Modified Mini-PCNL
Participants randomized to this arm will undergo 20 Fr modified mini percutaneous nephrolithotomy using the F17 Hawk nephroscope for the treatment of complex renal stones.
Procedure: 20 Fr Modified Mini Percutaneous Nephrolithotomy
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
Active Comparator: Standard PCNL
Participants randomized to this arm will undergo 24 Fr standard percutaneous nephrolithotomy using the F20.8 Wolf nephroscope for the treatment of complex renal stones.
Procedure: 24 Fr Standard Percutaneous Nephrolithotomy
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

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
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.
Within 72 hours after surgery

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
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.
3 months after surgery
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.
From surgery to hospital discharge, assessed up to 30 days after surgery

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

The First Affiliated Hospital of Guangzhou Medical University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

July 15, 2026

Primary Completion (Estimated)

July 14, 2027

Study Completion (Estimated)

September 14, 2027

Study Registration Dates

First Submitted

July 7, 2026

First Submitted That Met QC Criteria

July 7, 2026

First Posted (Actual)

July 13, 2026

Study Record Updates

Last Update Posted (Actual)

July 13, 2026

Last Update Submitted That Met QC Criteria

July 7, 2026

Last Verified

July 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • ES-2025-285-02
  • GMUCR2025-01006 (Other Grant/Funding Number: Guangzhou Medical University)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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