Cutting-Edge Treatment Modalities and Personalized Approaches
Urinary stone disease is a prevalent and often recurrent condition that poses a significant burden on both patients and healthcare systems. The management of urinary stones has undergone remarkable advancements in recent years, driven by the efforts of a global panel of urolithiasis experts. These experts convened at the Experts in Stone Disease Congress in Valencia in January 2024 to discuss the state-of-the-art in the field and explore future perspectives.
Surgical Treatment Options: Balancing Efficacy and Safety
The surgical treatment modalities for renal and ureteral stones are well-defined by the guidelines of international societies. However, for some index cases, alternative options may be considered. For instance, in the case of a 1.5 cm renal stone, both mini-percutaneous nephrolithotomy (m-PCNL) and retrograde intrarenal surgery (RIRS) have proven to be valid treatment alternatives with comparable stone-free rates.
The m-PCNL has demonstrated superior cost-effectiveness and a shorter operative time, while the RIRS has shown lower morbidity in terms of blood loss and shorter recovery times. Shockwave lithotripsy (SWL) has been less effective, particularly for lower calyceal stones, but it maintains the highest safety profile.
For a 6 mm obstructing stone of the pelviureteric junction (PUJ), SWL should be the first-line choice for stones less than 1 cm, due to its less invasive nature and lower risk of complications, although it has a lower stone-free rate. RIRS, on the other hand, offers advantages in certain conditions, such as anticoagulant treatment, obesity, or body deformity.
Navigating Procedural Challenges and Complications
In patients receiving antithrombotic therapy, SWL, percutaneous nephrolithotomy (PCN), and open surgery carry an elevated risk of hemorrhage or perinephric hematoma. Conversely, ureteroscopy (URS) is associated with less morbidity in these cases. An individualized assessment of the risks of bleeding and thromboembolism should guide the perioperative thromboprophylactic strategy.
Preoperative urine culture and antibiotic therapy are mandatory, although the treatment of urinary tract infections (UTIs) is becoming more challenging due to increasing resistance to routinely applied antibiotics. The use of an intrarenal urine culture and stone culture is recommended to adapt antibiotic therapy in case of postoperative infectious complications.
Monitoring temperature and pressure during RIRS is vital for ensuring patient safety and optimizing surgical outcomes, although the techniques for measurements and data analysis are still in need of refinement.
Ureteral stents have been improved through the development of new biomaterials, coatings, and stent designs. Current research focuses on the development of drug-eluting and bioresorbable stents.
While PCNL is considered the most invasive surgical option, it is associated with a fever and sepsis rate of 11% and 0.5%, respectively, as well as a need for transfusion and embolization for bleeding in 7% and 0.4% of cases. Major complications, such as colonic, splenic, liver, gallbladder, and bowel injuries, are quite rare but can result in significant morbidity. Ureteroscopy causes fewer complications, although some can be severe, such as those related to high pressure in the urinary tract (sepsis or renal bleeding) or the application of excessive force to the urinary tract (ureteral avulsion or stricture).
Comprehensive Diagnostic Workup: From Genetics to Urinary Biochemistry
Genetic testing allows for the diagnosis of monogenic conditions causing stones and should be carried out in children and selected adults. In adults, monogenic diseases can be diagnosed by systematic genetic testing in no more than 4% of cases, excluding cystinuria, APRT deficiency, and xanthinuria.
A reliable stone analysis by infrared spectroscopy or X-ray diffraction is mandatory and should be accompanied by examination of the stone under a stereomicroscope. The analysis of digital images of stones by deep convolutional neural networks in the laboratory or during endoscopic examination could enable the classification of stones based on their color and texture.
Scanning electron microscopy (SEM) in association with energy dispersive spectrometry (EDS) is another fundamental research tool for the study of kidney stones. The combination of metagenomic analysis using Next Generation Sequencing (NGS) techniques and the enhanced quantitative urine culture (EQUC) protocol can be used to evaluate the urobiome of renal stone formers.
Twenty-four-hour urine analysis has an important role during patient evaluation, along with repeated measurements of urinary pH using a digital pH meter. Urinary supersaturation is the most comprehensive physicochemical risk factor employed in urolithiasis research. Urinary macromolecules can act as both promoters or inhibitors of stone formation, depending on the chemical composition of the urine in which they are operating. However, there are currently no clinical applications of macromolecules in stone management or prophylaxis.
Patients should also be evaluated for the association with systemic pathologies, as urinary stones can be a manifestation of underlying metabolic or genetic disorders.
Personalized and Public Health Approaches to Prevent Recurrence
The management of urinary stones requires a multifaceted approach, combining personalized medicine and public health interventions to prevent stone recurrence effectively.
Personalized Medicine: Targeted Strategies for High-Risk Patients
Personalized medicine addresses a small portion of stone patients with a high risk of recurrence and systemic complications, requiring specific dietary and pharmacological treatment to prevent stone recurrence and complications of associated systemic diseases.
Stone analysis allows the identification of “high-risk” patients forming non-calcium stones, such as those with infection stones (struvite), uric acid and urates, cystine, and other rare stones (dihydroxyadenine, xanthine). Patients at “high-risk” forming calcium stones require a more complex diagnosis through clinical and laboratory evaluation, particularly those with cystinuria and primary hyperoxaluria.
Public Health Interventions: Reducing Prevalence in the General Population
The more numerous subjects who form one or a few stones during their entire lifespan should be treated by modifications of diet and lifestyle. Primary prevention through public health interventions is advisable to reduce the prevalence of stones in the general population.
Future Research: Harnessing the Power of Artificial Intelligence
The application of Artificial Intelligence (AI) is a promising avenue for the future management of urinary stones. AI-powered tools could enable the automated identification of ureteral stones on CT imaging, prediction of stone composition and 24-hour urinary risk factors based on demographics and clinical parameters, and assessment of stone composition through the evaluation of endoscopic images.
The synergy between urologists, nephrologists, and scientists in basic kidney stone research will enhance the depth and breadth of investigations, leading to a more comprehensive understanding of kidney stone formation and the development of innovative preventive and therapeutic strategies.
In conclusion, the management of urinary stones has seen remarkable advancements, with the adoption of personalized approaches and the integration of cutting-edge technologies. By continuing to push the boundaries of scientific knowledge and clinical practice, the field of urolithiasis is poised to offer better outcomes and improved quality of life for patients suffering from this prevalent condition.
