Clinical efficacy, safety, and costs of percutaneous occlusive balloon catheter-assisted ureteroscopic lithotripsy for large impacted proximal ureteral calculi: a prospective, randomized study.

PURPOSE: To evaluate the clinical efficacy, safety, and costs of percutaneous occlusive balloon catheter-assisted ureteroscopic lithotripsy (POBC-URSL) for large impacted proximal ureteral calculi. PATIENTS AND METHODS: 156 patients with impacted proximal ureteral stones ≥1.5 cm in size were randomized to ureteroscopic lithotripsy (URSL), POBC-URSL, and percutaneous nephrolithotomy (PNL) group between May 2010 and May 2013. For URSL, the calculi were disintegrated with the assistance of anti-retropulsion devices. POBC-URSL was performed with the assistance of an 8F percutaneous occlusive balloon catheter. PNL was finished with the combination of an ultrasonic and a pneumatic lithotripter. A flexible ureteroscope and a 200 µm laser fiber were used to achieve stone-free status to a large extent for each group. Variables studied were mean operative time, auxiliary procedure, postoperative hospital stay, operation-related complications, stone clearance rate, and treatment costs. RESULTS: The mean lithotripsy time for POBC-URSL was shorter than URSL, but longer than PNL (42.6±8.9 minutes vs 66.7±15.3 minutes vs 28.1±6.3 minutes, p=0.014). The auxiliary procedure rate and postoperative fever rate for POBC-URSL were significantly lower than URSL and comparable to PNL (p<0.01, p=0.034). POBC-URSL was superior to URSL with regard to the stone clearance rate at 3 days postoperatively, and as good as PNL (98.1% vs 75.0% vs 96.2%, p<0.01). The postoperative hospital stay and hematuria rate were lower in POBC-URSL group than PNL group and similar to URSL group (p=0.016, p<0.01). The treatment costs were lowest in POBC-URSL group ($1205.0±$113.9 vs $1731.7±$208.1 vs $2446.4±$166.4, p=0.004). CONCLUSIONS: For large impacted proximal ureteral calculi, POBC-URSL was associated with a higher stone clearance rate, fewer complications and costs. POBC-URSL combined the advantages of URSL and PNL.

Evaluation of urinary stones ex vivo with micro-computed tomography: preliminary results of an investigational technique.

PURPOSE: To evaluate the ultrastructural features of the urinary stones removed with endoscopic stone surgery, using micro computed tomography (micro-CT). MATERIALS AND METHODS: Patients who had endoscopic surgery for renal or ureteral stones removal were included in this study. After surgery, the stones were classified into three groups and investigated with Skyscan 1174 micro-CT. Group I underwent percutaneous nephrolithotomy (PNL) with ultrasonic lithotripsy; group II had ureteroscopic stone surgery (USS) with pneumatic lithotripsy; and group III (the control group) had stone removal with USS or PNL without lithotripsy. Stone homogeneity, voids, and the internal structure of the stones were evaluated. Chi-square test was used to evaluate the difference statistically. P values less than .05 were considered statistically significant. RESULTS: A total of 24 "calcium oxalate monohydrate" stones from 24 patients were scanned with micro-CT. Stones treated with ultrasonic lithotripsy (group I) were more fragile, fragmented, and cracked than those treated with the pneumatic lithotripsy (group II; P = .01). Stones in group II were more homogeneous and smooth than those in group I and resembled those of the control group (P = .02). Homogeneous, non-fragile stones and heterogeneous, fragile calculi were seen in all groups. CONCLUSION: The stone fragility could be confirmed by micro-CT investigation. Ultrasonic lithotripters increase the stone fragility, which is demonstrated with increased heterogeneity by micro-CT.

Structural features of three ureterocele calculi.

Ureterocele calculi are developed in cavities with urinary retention but far from the upper renal cavities. The structural features of three ureterocele calcium oxalate stones were observed by scanning electron microscope coupled with X ray microanalysis. The urinary parameters of the three patients were also determined. The stone A consisted of loose structure of large calcium oxalate dihydrate crystals and small spheres of hydroxyapatite. The interior contains disorganized plate-like calcium oxalate monohydrate crystals. The stone B was formed by a compact outer layer of calcium oxalate monohydrate columnar crystals. The structure of stone interior was similar to the stone A. The stone C was formed by concentric layers composed of either calcium oxalate monohydrate columnar crystals or hydroxyapatite. The core consisted of agglomerated calcium oxalate monohydrate crystals, hydroxyapatite and organic matter. From the urinary biochemical data it was deduced that two ureterocele patients (who formed A and B stones) were hypercalciuric (calcium > 300 mg/24 h), being 6.5 the urinary pH value of the patient that formed the A stone, and 7.0 the urinary pH of the patient that formed the C stone. The rest of urinary parameters for the three patients were normal. Thus, one of the requisite conditions for unattached stone development is the existence of a place inside the urinary tract where the solid particles that act as calculus initiator of the stone can be retained enough time to exert this action.

Aging assessment by dynamic mechanical analysis of in vivo encrusted polymeric urinary stents.

PURPOSE: To investigate the viscoelastic properties of plastic pigtail stents after removal from patients using the method of dynamic mechanical analysis (DMA). MATERIALS AND METHODS: Dynamic mechanical analysis was performed in 12 polymeric pigtail stents left indwelling for various periods of time (0-120 days). The encrustations were characterized by infrared spectroscopy, and their morphology was observed using scanning electron microscopy. RESULTS: Softening and stiffening behavior was observed. Stiffening was found specifically in the stents with heavy mineral deposits. CONCLUSIONS: Material degradation becomes obvious after certain periods of time. The effect of stent degradation appeared in two forms: softening of the stent polymer, possibly through interaction with urine, and stiffening of the stent secondary to the formation of various insoluble mineral deposits covered by layers of organic matrix.

[A study on bacteria within stones in urolithiasis].

The bacteria in 37 stones obtained from 37 patients with urinary stone diseases, that is, 11 renal stones (containing 2 staghorn calculi), 21 ureteral stones, 4 bladder stones and 1 urethral stone, were studied, according to the Nemoy & Stamey's method. The stones were collected by partial nephrectomy (1 case), nephrolithotomy (1 case), pyelolithotomy (1 case), percutaneous nephrolithotripsy (PNL) (6 cases), 12 ureterolithotomies, transurethral ureterolithotripsy (2 cases), cystolithotripsies (4 cases) and spontaneous deliveries (10 cases). According to a stone analysis by infrared spectrophotometer revealed 30 were noninfection stones (81.1%) and 7 infection stones (18.9%). Of these 37 stones, 5 stones (13.5% of 11 stones) had bacteria within them. These stones consisted of 4 infection stones (57.1% of all infection stones) and 1 noninfection stone (3.3% of all noninfection stones). Out of 4 patients having bacteria within their stones, urine culture of whom were carried out before stones were collected, only one patient (25%) had the same species of bacterium (E. coli) both within the stone and in urine. The E. coli within the stone and that in urine, however, showed quite different reactions to some antibiotics. The fact that all organisms within stones cannot be detected by urine culture before collecting stones of the patients in our present study, suggests that patients undergoing endourological surgery, such as extracorporeal shock wave lithotripsy and PNL, may have a risk of complications, such as severe urinary tract infection and urosepsis, if the possibility of the presence of organisms within stones is not taken into consideration.

Ultrastructural microbiology of infected urinary stone.

Scanning and transmission electron microscopy of an antibiotic-treated infected urinary stone demonstrates a thick bacterial biofilm adhering to the surface of the stone. Cultures of the crushed calculi indicated the viability of the bacteria. Exopolysaccharide secreted by the bacteria develops a matrix or glycocalyx that appears to protect the biofilm-forming sessile bacteria from antibiotics.