Characterization of Intracalyceal Pressure During Ureteroscopy

Our manuscript published on May 27, 2020 in the World Journal of Urology, is the first report of real-time measurement of intracalyceal pressure during ureteroscopy within a kidney.

Pressurized irrigation used during endoscopy allows your urologist the best view when treating kidney stones. This is particularly important, as clear visualization is needed when laser fibers are used to break up stones and when these fragments are subsequently removed with baskets. However, the concern is pressurized irrigation results in fluid backflow into your kidney, which could lead to an infection. Utilizing a miniaturized pressure transducer that is commonly used to treat heart attack patients, the UCI Kidney Stone Center researchers measured pressure within different parts of a kidney for the first time in the world. This information will allow urologists to use pressurized irrigation more judiciously during ureteroscopy, which has the potential to reduce infections while performing the most common type of surgery urologists perform in the United States today.

Innovative Force Sensor

A ureteral access sheath is like a protective tube for your ureter. Urologists insert these “tubes” into your ureter to allow safe passage of surgical tools and to maintain access to your kidneys and kidney stones. Our team developed and tested an innovative force-sensing device to study the maximum amount of force any urologist should use (8 Newtons) to avoid ureteral injury or tearing.

Procedure: Automated vs. Manual

Urologists have an optimal view of your kidney stones through a ureteroscope, if water irrigation or flow and pressure is maintained. Imagine if during your procedure, your urologist’s eyes were relying on your circulating nurse to manually pump or push water through a small straw while maintaining constant pressure and flow. We sought to compare the newest automated irrigation pump technology on the market to the traditional hand pump. We found that with an automated pump, workflow time reduced in the operating room and nurse satisfaction increased.

First to Map Out Kidney Blood Flow Using innovative Doppler Ultrasonography

In a porcine model, a miniaturized Doppler ultrasound probe used during ureteroscopy demonstrated that the renal papilla had the least amount of blood flow, whereas the infundibula had the highest blood flow. This data may serve to inform site selection during percutaneous nephrostomy needle placement.

Laser From the Inside Out

Percutaneous nephrolithotomy (PCNL) remains a challenging procedure, primarily due to surgical difficulties when obtaining access to the kidneys, by puncturing a needle from a patient’s back to the kidney. Few urologists obtain their own access even under fluoroscopic or ultrasonic guidance. We are the first to report and successfully perform the use of holmium laser energy under endoscopic guidance to obtain access from the inside out. The accuracy of nephrostomy tube placement and lessening of fluoroscopy time are two potential benefits of this approach.

Enlarging the Kidney’s Collecting System for Procedural Planning

Non-contrast CT scans are commonly used when planning how to procedurally approach your kidney stone. Our team sought to evaluate an innovative DRINK protocol including oral hydration and diuretic, to enlarge the kidney’s collecting system prior to this scan. The DRINK protocol significantly increased the visible collecting system volume and surface area. In the majority of cases, the width of the inside and outside of the kidney was expanded.

Relaxed Ureter = Large Diameter Access Sheath

Remember the small straw analogy? We sought to find a medical expulsive therapy which would maximize the relaxation of your ureter prior to ureteral access insertion. We found that with the use of oral Tamsulosin (i.e., medical impulsive therapy), there was an increase in cases where large access sheath was achieved without the use of a pre-operative ureteral stent placement.

Gravity Works

When using a laser to break up kidney stones, fragments can flow back up into your kidney. We found that increasing the angle you position the operating room bed can effectively prevent this from occurring. In other words: Gravity Works!

Laying Down or Facing Up?

Percutaneous nephrolithotomy (PCNL) is used for large and complex renal stones. Because it’s a challenging procedure, its technique, equipment, and even patient positioning have undergone adjustments over time. Prone position (patient lying face-down) is most widely used, but the supine position (patient lying face-up) has been introduced, bringing the optimal position into debate. Our team looked at published data and determined that neither approach is significantly superior to the other. Rather, modern-day PCNL techniques have made it possible for either position to be used.

Pellethane®: A Material That Resists Encrustation

Encrustation of implanted urinary tract devices is associated with significant illness. Pellethane® is a polyether-based material that is strong, porous and resistant to solvents. We assessed Pellethane® with and without surface coatings for the potential to resist encrustation in an artificial urine environment. Pellethane®, particularly with a HEMA-based preventative coating, may serve as a favorable alternative to traditional urinary stent material, providing its improved resistance to encrustation.

Smartphone Technology

Smartphone technology has propelled the evolution of health-related mobile technology, referred to as mobile health (mHealth). With the rise of smartphone ownership and the growing popularity of health-related smartphone usage, mHealth offers potential benefits for both patients and healthcare providers. Our team reviewed publications focused on the use of smartphones in urology to evaluate any benefit of smartphone technology over standard of care. We found that while smartphone technology is constantly evolving and has the potential to improve urological care and education, of concern to consumer and urologist alike is that these downloadable programs are limited due to the accuracy of their content, risk of confidentiality breach, and the lack of central regulation and professional involvement in their development.


The Endockscope system (ES) combines a smartphone, lens system, and a rechargeable LED light source to provide a low-cost alternative ($45) to the standard camera and high-powered light source ($45,000) used in traditional endoscopic procedures. Our team assessed the performance and diagnostic capability of the ES system vs. the standard endoscopic system using four rigid/semi-rigid endoscopes. We found that he ES plus the Apple iPhone X or Samsung Galaxy S9+ offers comparable imaging and provides diagnostic information equivalent to the standard system for rigid endoscopy of the kidney, ureter, and bladder; the Galaxy S9+ provides comparable imaging and diagnostic capabilities for evaluation of the abdomen.

Endockscope II

The Endockscope system (ES) combines a smartphone, LED light source, and fiberoptic cystoscope for mobile videocystocopy. Our team compared the conventional method of videocystocopy with the Endockscope (used with next generation smarthpones) to evaluate image quality/resolution, brightness, color quality, sharpness, and acceptability for diagnostic use. When coupled with an Apple iPhone 7 or Samsung Galaxy S8, the Endockscope system ($45) was comparable to conventional videocystoscopy ($45,000).

Drink Coconut Water

Coconut water has long been publicized for its medicinal qualities, including natural hydration. We sought to determine if consumption would change factors affecting the formation of kidney stones. We found that coconut water consumption increases urinary potassium, chloride, and citrate without altering urine pH.

Virtual Reality

Percutaneous nephrolithotomy (PCNL) requires the urologist to have detailed knowledge of the stone and its relationship with the renal anatomy. Our team looked at how immersive virtual reality (iVR) can benefit both surgeons and patients when compared to CT alone. We found that iVR improved urologists’ understanding of renal anatomy and altered the preoperative approach in 40% of cases. It also contributed to decreased fluoroscopy time and less blood loss. For patients, iVR reduced preoperative anxiety and improved their understanding of stone disease.

Flow Rates

Our team evaluated the flow characteristics of manual and automated-pump irrigation systems connected to a flexible ureteroscope. The flow rates of irrigation produced by both types of pump were similar at pressures of 150 and 200 mm Hg, regardless of the occupancy of a ureteroscope’s working channel during the first 5 minutes of irrigation. The pressure at the entry site of the ureteroscopy is subject to significant variability with use of the manual pump when compared to the automated pump.