Kidney StonesNCT07072598
Comparing Efficiency and Stone-Free Rates Mini PCNL vs Flex URS
A study testing ClearPETRA suction access sheath in people with Kidney Stones and Nephrolithiasis, run by Northwestern University at 1 site in United States.
Trial summary
The objective of the study is to compare the stone free rates with ureteroscopy utilizing the ClearPETRA suction ureteral access sheath, and mini-PCNL; both procedures and ClearPETRA sheaths are standard of care and are used regularly for stone treatment. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Kidney Stones, Nephrolithiasis, Urolithiasis
- What is being tested?
- ClearPETRA suction access sheath
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 0 participants
- Where
- 1 siteUnited States
- Study dates
- Apr 2026to Dec 2027
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Patients 18 years or older
- Have a CT scan showing renal stones 1-3cm in length
- Patients who will be able to read, understand, and complete patient questionnaires
Who cannot join
- Pregnant individuals
- Those with anomalous renal anatomy
- Patients with a urinary diversion (ex: Ileal conduit, reservoir, bladder substitute, etc.)
- Any condition rendering patient medically unfit to undergo either procedure (Bleeding diasthesis)
- Patients who lack decisional capacity
- Patients who are non-english speakers*
- Non-recruitment of non-english speakers is due to the study being a small pilot study that is used to assess the stone free rate for patients treated with a ureteroscopy or mini-PCNL using ClearPETRA suction access sheaths in a small portion of our patient population seeking treatment for stones. The team also does not possess the bandwidth or personnel to consent patients who are non-English speaking.
Trial locations and contacts
1 site in 1 country.
United States1 site
Northwestern Memorial Hospital
Chicago, Illinois, 60611
About this study
Official title: Comparing Efficiency and Stone-Free Rates After Mini-Percutaneous Nephrolithotomy and Flexible Ureteroscopy With Suction Access Sheaths
The objective of the study is to compare the stone free rates with ureteroscopy utilizing the ClearPETRA suction ureteral access sheath, and mini-PCNL; both procedures and ClearPETRA sheaths are standard of care and are used regularly for stone treatment. Our primary objective is to assess the complete stone free rate with both procedures.
Read the detailed description
With the advent of mini-PCNLs, some endourologists have been utilizing the technique to treat renal calculi up to 3cm in size with better stone free rates and similar comorbidity compared to ureteroscopy. These procedures require percutaneous renal access, and it is associated with greater length of stay and fluoroscopy time.
The ClearPETRA ureteral access sheath has shown great promise with improving stone free rates, decreasing intra-renal pressure and delivering some of the benefits of mini-PCNL without the added risk associated with obtaining percutaneous renal access.
The ClearPETRA flexible suction ureteral access sheath anecdotally improves efficiency and allows endourologists to better clear stone debris when compared to traditional ureteral access sheaths. We have yet to see a comparison between suction ureteral access sheaths and mini-PCNL with the suction renal access sheath.
Study Hypothesis: Compared to traditional access sheaths, using ClearPETRA access sheaths will result in an improvement in stone free rates with both modalities, with lower complications. Using ClearPETRA access sheaths in both modalities compared to traditional access sheaths should result in less of a difference in stone free rates between the ureteroscopy group and the mini-PCNL group.
- Conditions
- Kidney Stones, Nephrolithiasis, Urolithiasis
- Being tested
- ClearPETRA suction access sheath
- Keywords
- kidney stone, Ureteroscopy, Mini-PCNL, ClearPETRA, kidney stone interventional treatment, kidney stone 1cm-3cm
- Medical subject headings
- Kidney Calculi, Nephrolithiasis, Urolithiasis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ClearPETRA suction access sheathDevice
Ureteroscopy utilizing the ClearPETRA suction access sheath.
ClearPETRA suction access sheathDevice
Mini-PCNL utilizing the ClearPETRA suction access sheath
| Study group | Role | What they receive |
|---|---|---|
| Ureteroscopy | Active comparator | Patients randomized to this arm will have their stones treated using the method of Ureteroscopy in a standardized fashion. A second 0.035in sensor guidewire will then be advanced up to the renal pelvis with placement confirmed by fluoroscopy. Placement of a 12/14Fr ClearPETRA ureteral access sheath will be attempted. If this is unsuccessful, a 11/13Fr ClearPETRA ureteral access sheath will be advanced over the wire. If this is unsuccessful, a 5Fr open ended ureteral catheter will be placed and procedure will be converted to a miniPCNL. Lithotripsy will be performed with the MOSES 2.0 high power Holmium laser with settings of 0.3J and 120Hz or 2J and 20Hz depending on stone location and appearance. Stones will be extracted with the suction access sheath. A ureteral stent will be placed at the conclusion of the procedure. Receives: Device: ClearPETRA suction access sheath |
| Mini-PCNL | Active comparator | Will be performed by first starting with supine flexible cystoscopy to cannulate the ureteral orifice with a 5Fr open ended ureteral catheter. The patient will then be repositioned prone with 1-2 bumps placed transversely across the chest. Contrast will be instilled into the ureteral catheter and renal access will be obtained fluoroscopically with the triangulation technique. Once access is obtained, the tract will be dilated to 20Fr and a 18/20Fr ClearPETRA renal access sheath will be inserted to assess the collecting system. If there is concern that the 20Fr access is not sufficient to clear the stone, the tract will be upsized to 24 or 30Fr. The stones will be evacuated with the Trilogy Lithotripter and/or laser, suction and/or basket extraction. A ureteral stent will be placed at the conclusion of the procedure. Receives: Device: ClearPETRA suction access sheath |
What is being measured
The primary outcome is the main question the study is designed to answer.
Stone free rate
Stone free rate (no residual stone) on post-procedure CT
Measured: 4 weeks post-procedure
Secondary outcomes (9)
Surgery time
Surgery time (minutes)
Measured: Procedure day (1 day)
Complication rate
Complication rate (Clavien-Dindo) (%)
Measured: Procedure day (1 day)
Unplanned hospital visits
Unplanned hospital visits (ED/clinic)
Measured: 90 days postoperatively
Need for additional procedure
Need for additional procedure (within 90 days postoperatively)
Measured: 90 days postoperatively
Length of stay
Length of stay hospital stay (if admitted post-procedure, or readmitted)
Measured: Perioperatively (starting at Baseline/Procedure Date)
Inability to access ureter
Intra-operative complications including inability to access the ureter ureteroscopically or need to upsize the renal access sheath with the percutaneous approach.
Measured: Procedure day (1 day)
Need to upsize from 18Fr Sheath
Need to upsize from 18Fr (PCNL group)
Measured: Procedure day (1 day)
Occurrence of post-procedure sepsis
Post-op sepsis
Measured: Perioperatively (starting at Baseline/Procedure Date)
Hospital / patient costs (in total for procedure and any necessary postoperative hospital admissions or procedures related to the initial procedure).
Any necessary postoperative hospital admissions or procedures related to the initial procedure
Measured: Perioperatively (starting at Baseline/Procedure Date)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Jul 2025
- Study startApr 2026 (estimated)
- Primary completionJul 2027 (estimated)
- Study completionDec 2027 (estimated)
Why it stopped: Over the past year flexible and navigable suction ureteral access sheaths (FANS) has become the standard of care for small to moderate sized stones and mini PCNL has basically become a rare procedure.
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Kidney StonesStudies of the same condition, open and under way.
- More trials run by Northwestern UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 0 participants (actual)
Sponsor and investigators
- Lead sponsor
- Northwestern University
- Sponsor type
- University, hospital or other
- Collaborators
- KARL STORZ Endoscopy-America, Inc.
- Responsible party
- Principal investigator, Amy Krambeck, Northwestern University
- Investigators
- Amy E Krambeck, MD, Principal investigator, Northwestern University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07072598
- Sponsor's protocol ID
- STU00222993
- Status last verified
- Aug 2026
- First submitted
- 24 Jun 2025
- Last updated
- 20 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- Yes
Study at a glance
From the registry record, last updated by the sponsor on 20 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Comparing Efficiency and Stone-Free Rates After Mini-Percutaneous Nephrolithotomy and Flexible Ureteroscopy With Suction Access Sheaths
- ClinicalTrials.gov ID
- NCT07072598
- Acronym / sponsor ID
- STU00222993
- Conditions
- Kidney Stones, Nephrolithiasis, Urolithiasis
- Keywords
- kidney stone, Ureteroscopy, Mini-PCNL, ClearPETRA, kidney stone interventional treatment, kidney stone 1cm-3cm
- Study type
- Interventional
- Recruitment status
- WithdrawnReason stopped: Over the past year flexible and navigable suction ureteral access sheaths (FANS) has become the standard of care for small to moderate sized stones and mini PCNL has basically become a rare procedure.
- Enrolment
- 0 participants (actual)
- Lead sponsor
- Northwestern UniversityUniversity, hospital or other
- Collaborators
- KARL STORZ Endoscopy-America, Inc.
- Study start
- Apr 2026 (estimated)
- Primary completion
- Jul 2027 (estimated)
- Study completion
- Dec 2027 (estimated)
- First posted
- 18 Jul 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The objective of the study is to compare the stone free rates with ureteroscopy utilizing the ClearPETRA suction ureteral access sheath, and mini-PCNL; both procedures and ClearPETRA sheaths are standard of care and are used regularly for stone treatment. Our primary objective is to assess the complete stone free rate with both procedures.
Detailed description
With the advent of mini-PCNLs, some endourologists have been utilizing the technique to treat renal calculi up to 3cm in size with better stone free rates and similar comorbidity compared to ureteroscopy. These procedures require percutaneous renal access, and it is associated with greater length of stay and fluoroscopy time.
The ClearPETRA ureteral access sheath has shown great promise with improving stone free rates, decreasing intra-renal pressure and delivering some of the benefits of mini-PCNL without the added risk associated with obtaining percutaneous renal access.
The ClearPETRA flexible suction ureteral access sheath anecdotally improves efficiency and allows endourologists to better clear stone debris when compared to traditional ureteral access sheaths. We have yet to see a comparison between suction ureteral access sheaths and mini-PCNL with the suction renal access sheath.
Study Hypothesis: Compared to traditional access sheaths, using ClearPETRA access sheaths will result in an improvement in stone free rates with both modalities, with lower complications. Using ClearPETRA access sheaths in both modalities compared to traditional access sheaths should result in less of a difference in stone free rates between the ureteroscopy group and the mini-PCNL group.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Ureteroscopy | Active comparator | Device: ClearPETRA suction access sheathPatients randomized to this arm will have their stones treated using the method of Ureteroscopy in a standardized fashion. A second 0.035in sensor guidewire will then be advanced up to the renal pelvis with placement confirmed by fluoroscopy. Placement of a 12/14Fr ClearPETRA ureteral access sheath will be attempted. If this is unsuccessful, a 11/13Fr ClearPETRA ureteral access sheath will be advanced over the wire. If this is unsuccessful, a 5Fr open ended ureteral catheter will be placed and procedure will be converted to a miniPCNL. Lithotripsy will be performed with the MOSES 2.0 high power Holmium laser with settings of 0.3J and 120Hz or 2J and 20Hz depending on stone location and appearance. Stones will be extracted with the suction access sheath. A ureteral stent will be placed at the conclusion of the procedure. |
| Mini-PCNL | Active comparator | Device: ClearPETRA suction access sheathWill be performed by first starting with supine flexible cystoscopy to cannulate the ureteral orifice with a 5Fr open ended ureteral catheter. The patient will then be repositioned prone with 1-2 bumps placed transversely across the chest. Contrast will be instilled into the ureteral catheter and renal access will be obtained fluoroscopically with the triangulation technique. Once access is obtained, the tract will be dilated to 20Fr and a 18/20Fr ClearPETRA renal access sheath will be inserted to assess the collecting system. If there is concern that the 20Fr access is not sufficient to clear the stone, the tract will be upsized to 24 or 30Fr. The stones will be evacuated with the Trilogy Lithotripter and/or laser, suction and/or basket extraction. A ureteral stent will be placed at the conclusion of the procedure. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- Patients 18 years or older
- Have a CT scan showing renal stones 1-3cm in length
- Patients who will be able to read, understand, and complete patient questionnaires
Key exclusion criteria (7 listed)
- Pregnant individuals
- Those with anomalous renal anatomy
- Patients with a urinary diversion (ex: Ileal conduit, reservoir, bladder substitute, etc.)
- Any condition rendering patient medically unfit to undergo either procedure (Bleeding diasthesis)
- Patients who lack decisional capacity
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| ClearPETRA suction access sheathUreteroscopy utilizing the ClearPETRA suction access sheath. | Device | Ureteroscopy |
| ClearPETRA suction access sheathMini-PCNL utilizing the ClearPETRA suction access sheath | Device | Mini-PCNL |
Primary outcome
Stone free rate
Time frame: 4 weeks post-procedure
Stone free rate (no residual stone) on post-procedure CT
9 secondary outcomes
Surgery time
Time frame: Procedure day (1 day)
Complication rate
Time frame: Procedure day (1 day)
Unplanned hospital visits
Time frame: 90 days postoperatively
Need for additional procedure
Time frame: 90 days postoperatively
Length of stay
Time frame: Perioperatively (starting at Baseline/Procedure Date)
Inability to access ureter
Time frame: Procedure day (1 day)
Need to upsize from 18Fr Sheath
Time frame: Procedure day (1 day)
Occurrence of post-procedure sepsis
Time frame: Perioperatively (starting at Baseline/Procedure Date)
Hospital / patient costs (in total for procedure and any necessary postoperative hospital admissions or procedures related to the initial procedure).
Time frame: Perioperatively (starting at Baseline/Procedure Date)
Results and safety
The study was withdrawn before enrolling participants, so there are no results.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 20 Aug 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Amy E Krambeck, MD principal investigator
Northwestern University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing ClearPETRA suction access sheath in people with Kidney Stones and Nephrolithiasis, run by Northwestern University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: withdrawn, as of the sponsor's last update on 20 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study was withdrawn before enrolling participants, so there are no results.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Stone free rate (time frame: 4 weeks post-procedure). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 20 Aug 2026.