Medical and Interventional Management of Upper Urinary Tract Uroliths

Establishment of a new predictive model for the recurrence of upper urinary tract stones

PURPOSE

To construct a nomogram for evaluation of the recurrence risk of upper urinary tract stones in patients.

METHODS

We retrospectively reviewed the clinical data of 657 patients with upper urinary tract stones and divided them into stone recurrence group and non-recurrence group. Blood routine, urine routine, biochemical, and urological CT examinations were searched from the electronic medical record, relevant clinical data were collected, including age, BMI, stones number and location, maximum diameter, hyperglycemia, hypertension, and relevant blood and urine parameters. The Wilcoxon rank-sum test, independent sample t test, and Chi-square test were used to preliminarily analyze the data of the two groups, then LASSO and logistic regression analysis were used to find out the significant difference indicators. Finally, R software was used to draw a nomogram to construct the model, and ROC curve was drawn to evaluate the sensitivity and specificity.

RESULTS

The results showed that multiple stones (OR: 1.832, 95% CI 1.240-2.706), bilateral stones (OR: 1.779, 95% CI 1.226-2.582), kidney stones (OR: 3.268, 95% CI 1.638-6.518), and kidney ureteral stones (OR: 3.375, 95% CI 1.649-6.906) were high risk factors. And the stone recurrence risk was positively correlated with creatinine (OR: 1.012, 95% CI 1.006-1.018), urine pH (OR: 1.967, 95% CI 1.343-2.883), Apo B (OR: 4.189, 95% CI 1.985-8.841) and negatively correlated with serum phosphorus (OR: 0.282, 95% CI 0.109-0.728). In addition, the sensitivity and specificity of the prediction model were 73.08% and 61.25%, diagnosis values were greater than any single variable.

CONCLUSION

The nomogram model can effectively evaluate the recurrence risk of upper urinary stones, especially suitable for stone postoperative patients, to help reduce the possibility of postoperative stone recurrence.

Development of a burst wave lithotripsy system for noninvasive fragmentation of ureteroliths in pet cats

BACKGROUND

Upper urinary tract stones are increasingly prevalent in pet cats and are difficult to manage. Surgical procedures to address obstructing ureteroliths have short- and long-term complications, and medical therapies (e.g., fluid diuresis and smooth muscle relaxants) are infrequently effective. Burst wave lithotripsy is a non-invasive, ultrasound-guided, handheld focused ultrasound technology to disintegrate urinary stones, which is now undergoing human clinical trials in awake unanesthetized subjects.

RESULTS

In this study, we designed and performed in vitro testing of a modified burst wave lithotripsy system to noninvasively fragment stones in cats. The design accounted for differences in anatomic scale, acoustic window, skin-to-stone depth, and stone size. Prototypes were fabricated and tested in a benchtop model using 35 natural calcium oxalate monohydrate stones from cats. In an initial experiment, burst wave lithotripsy was performed using peak ultrasound pressures of 7.3 (n = 10), 8.0 (n = 5), or 8.9 MPa (n = 10) for up to 30 min. Fourteen of 25 stones fragmented to < 1 mm within the 30 min. In a second experiment, burst wave lithotripsy was performed using a second transducer and peak ultrasound pressure of 8.0 MPa (n = 10) for up to 50 min. In the second experiment, 9 of 10 stones fragmented to < 1 mm within the 50 min. Across both experiments, an average of 73-97% of stone mass could be reduced to fragments < 1 mm. A third experiment found negligible injury with in vivo exposure of kidneys and ureters in a porcine animal model.

CONCLUSIONS

These data support further evaluation of burst wave lithotripsy as a noninvasive intervention for obstructing ureteroliths in cats.

Modified endoluminal ureteral stenting for the management of proximal ureteral obstruction in two cats

Case series summary

Two cases of placement of modified endoluminal ureteral stents are described, for revision of a subcutaneous ureteral bypass (SUB) and for primary treatment of obstructive ureterolithiasis. Modified endoluminal stents were inserted through the ureterotomy, anchored in the renal pelvis with a single pigtail and shortened to a length sufficient to span the proximal ureter and ureterotomy site.

Relevance and novel information

The advantages of this approach as a surgical option for feline obstructive ureterolithiasis are demonstrated, including the avoidance of disruption, or bypass, of the ureterovesicular junction, minimisation of implanted foreign material and avoidance of intravesicular stent mass, maintenance of the physiological route of urine flow, including preservation of active distal ureteral function, and limitation of the potential complications of ureterotomy. The clinical efficacy of this adaptation of the previously published endoluminal stenting technique is demonstrated with its applicability de novo and in the revision of other stenting procedures.

Transmural migration of a subcutaneous ureteral bypass into the intestine in three cats

Subcutaneous ureteral bypass™ is a device placed in cats with ureteral obstruction. The most common complications include system occlusion, urinary tract infection and sterile cystitis. In this case series, we describe three cats with subcutaneous ureteral bypass devices placed where transmural migration of subcutaneous ureteral bypass catheters into the small intestine resulted in gastrointestinal signs, urinary infection and subcutaneous ureteral bypass occlusion. The system was changed in one case and removed in the other two. In all cases, an intestinal resection and anastomosis was performed. All cats had a good medium-term outcome, and urinary infection persisted in the case for which the subcutaneous ureteral bypass system was changed. Transmural migration of the device should be ​considered in cats with subcutaneous ureteral bypass presenting with persistent urinary tract infection, gastrointestinal signs or device obstruction, even if imaging studies such as ultrasound or contrast studies do not demonstrate any abnormalities.

Is there a place for extracorporeal shockwave lithotripsy (ESWL) in the endoscopic era?

This retrospective study aimed to evaluate whether there was still a place for ESWL therapy in the endourological era. From 1988 to 2018, ESWL therapy was performed with 3 successive types of lithotripters in our hospital. From 1988 to 1998, the electrohydraulic lithotripter NS-15 was used, and the electromagnetic lithotripter HK-V was put to use in 1999. Since 2010, the electromagnetic lithotripter HK-Vm has been used. Over the 30-year period, 16,969 urolithiasis patients underwent ESWL therapy, including 124 paediatric cases and 178 special cases. The stone clearance rate (SCR) and postoperative complications in the 3 lithotripter groups were recorded and analysed. The SCR was estimated by ultrasonography or plain X-ray, while the complications were recorded by the modified Clavien grading system. The primary stone clearance rate (pSCR) of ureteral and renal stones was significantly improved in the HK-Vm group compared with the NS-15 and HK-V groups. The final stone clearance rate (fSCR) of lower calyx stones was considerably higher in the HK-Vm group (55.9%) than in the NS-15 (41.1%) and HK-V (44.1%) groups. Most complications were grade I and II, while the incidence of grade III and above complications was less than 3%. Additionally, the fSCR in paediatric and special cases ranged from 66.5% to 83.5%, with no record of severe complications. As our data showed, ESWL was effective and safe for most urolithiasis patients, including paediatric patients and special cases. Therefore, ESWL is still the major treatment option in the current endourological era.

Subcutaneous ureteral bypass device placement with intraoperative ultrasound guidance, with or without microsurgical ureterotomy, in 24 cats

OBJECTIVES

The aim of this study was to describe a method of subcutaneous ureteral bypass (SUB) device placement with intraoperative ultrasound guidance, with or without microsurgical ureterotomy, for the treatment of benign ureteral obstruction(s) in cats. A secondary aim was to describe the complications and outcomes in our population, and compare the two groups with and without ureterotomy.

METHODS

The medical records of cats with benign ureteral obstruction(s) treated with SUB device placement with intraoperative ultrasound guidance between April 2013 and June 2018 were reviewed.

RESULTS

Twenty-four cats with 30 obstructed ureters had a SUB device placement with intraoperative ultrasound guidance in 26 surgeries. A microsurgical ureterotomy was performed in 14/26 surgeries. Median age was 10.07 years (range 4-16.6). Eleven of 24 cats (46%) had a previous history of chronic kidney disease (CKD). All cats, including two patients with minimal pelvic dilation (⩽4 mm), had a successful intrapelvic placement of the SUB device. Median survival time was 1555 days (4.25 years); this was not significantly different between the two groups (P = 0.4494). Stone analysis and bacterial culture, where available for review, revealed calcium oxalate in 12/12 and a negative culture in 6/7. The ureterotomy significantly prolonged the procedure duration (180 vs 125 mins) without significantly decreasing the short- and long-term complications (P = 0.1588 and P = 0.2921, respectively), or the survival time (P = 0.8437).

CONCLUSIONS AND RELEVANCE

SUB device placement with intraoperative ultrasound guidance is an effective alternative for the treatment of ureteral obstruction. Ultrasound guidance may be a more accessible option when a trained veterinarian does not have access to fluoroscopy. Microsurgical ureterotomy did not show any advantage and prolonged the anesthesia. Our median survival time emphasizes a good outcome of SUB device placement, even in cats with a previous history of CKD.

Cutaneous seeding of transitional cell carcinoma of the urinary bladder after placement of a subcutaneous ureteral bypass device in a dog with bilateral ureteral obstruction

CASE DESCRIPTION

A 12-year-old spayed female Jack Russell Terrier was presented with pollakiuria and stranguria.

CLINICAL FINDINGS

Transitional cell carcinoma (TCC) of the urinary bladder trigone and urethra was diagnosed via CT, cystoscopic, and histologic examinations. Azotemia developed 2 weeks following diagnosis, secondary to bilateral ureteral obstruction.

TREATMENT AND OUTCOME

Percutaneous antegrade ureteral stenting was unsuccessful; therefore, a subcutaneous ureteral bypass (SUB) device with 2 nephrostomy and 1 cystostomy catheters was surgically placed. Two months following placement of the SUB device, the dog developed a firm, multilobulated cutaneous mass at the site of the subcutaneous access port of the SUB device. Results of cytologic examination of cells aspirated from the mass were consistent with TCC. Within 1 month of confirmation of TCC of the cutaneous mass, the mass was ulcerated and infected, and the dog was euthanized because of signs of pain and perceived poor quality of life.

CLINICAL RELEVANCE

Seeding of neoplastic cells is a known complication of needle aspiration or biopsy or surgery in people and dogs with carcinomas. The occurrence of TCC at the SUB port site suggested caution with the placement of a SUB device in dogs with obstructive TCC.