Purpose Although minimal evidence exists, bladder calculi in men with benign prostatic hyperplasia are thought to be secondary to bladder outlet obstruction induced urinary stasis. We performed a prospective, multi-institutional clinical trial to determine whether metabolic differences were present in men with and without bladder calculi undergoing surgical intervention for benign prostatic hyperplasia induced bladder outlet obstruction. Materials and Methods Men who elected surgery for bladder outlet obstruction secondary to benign prostatic hyperplasia with and without bladder calculi were assessed prospectively and compared. Men without bladder calculi retained more than 150 ml urine post-void residual urine. Medical history, serum electrolytes and 24-hour urinary metabolic studies were compared. Results Of the men 27 had bladder calculi and 30 did not. Bladder calculi were associated with previous renal stone disease in 36.7% of patients (11 of 30) vs 4% (2 of 27) and gout was associated in 13.3% (4 of 30) vs 0% (0 of 27) (p <0.01 and 0.05, respectively). There was no observed difference in the history of other medical conditions or in serum electrolytes. Bladder calculi were associated with lower 24-hour urinary pH (median 5.9 vs 6.4, p = 0.02), lower 24-hour urinary magnesium (median 106 vs 167 mmol, p = 0.01) and increased 24-hour urinary uric acid supersaturation (median 2.2 vs 0.6, p <0.01). Conclusions In this comparative prospective analysis patients with bladder outlet obstruction and benign prostatic hyperplasia with bladder calculi were more likely to have a renal stone disease history, low urinary pH, low urinary magnesium and increased urinary uric acid supersaturation. These findings suggest that, like the pathogenesis of nephrolithiasis, the pathogenesis of bladder calculi is likely complex with multiple contributing lithogenic factors, including metabolic abnormalities and not just urinary stasis.

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RESULTS• Of the 2651 patients studied, 182 (6.9%) presented with M1 RCC. Tumour size was significantly greater in patients with M1 RCC than in patients with M0 RCC (a median size of 10 vs 4.5 cm; P < 0.001). Only 1 of the 629 patients (0.2%) with a tumour < 3 cm had M1 RCC and that tumour was 2.5 cm. The risk of M1 RCC increased from 1.1% for patients with tumours 3-3.9 cm to 16.5% for patients with tumours ≥ 7 cm.• Of the 2124 patients with M0 RCC, 430 developed distant metastases at a median (range) of 1.4 (0.1-16.2) years after surgery. Only 9 of the 498 patients (1.8%) with a tumour < 3 cm developed distant metastases after surgery.• Each 1-cm increase in tumour size increased the risk of death from RCC by 20% [hazard ratio (HR) 1.20; 95% confidence interval (CI) 1.18-1.22; P < 0.001] and death from any cause by 10% (HR 1.10; 95% CI 1.09-1.12; P < 0.001).• For the 1346 patients who were still alive at last follow-up, the median (range) duration of follow-up was 6.9 (0.1-19.7) years. CONCLUSIONS• Tumour size is significantly associated with metastases in patients with renal masses.• Patients with tumours < 3 cm have a low risk of synchronous metastatic disease. KEYWORDSkidney neoplasms, renal cell carcinoma, nephrectomy, recurrence, neoplasm staging, neoplasm metastasis Study Type -Prognosis (case series) Level of Evidence 4 OBJECTIVE• To determine the metastatic potential of renal masses based on original tumour size. MATERIALS AND METHODS• We identified 2651 patients who had undergone surgical resection for a unilateral, sporadic renal tumour between 1990 and 2006.• Associations of tumour size with synchronous metastasis at presentation [M1 renal cell carcinoma (RCC)] and development of metastases, death from RCC, and death from any cause after surgery were evaluated using logistic and Cox proportional hazards regression.

We conclude that UFP can be successfully managed with endoscopic techniques. Postoperative surveillance is recommended for potential early detection of ureteral stricture or recurrence.

Autosomal dominant polycystic kidney disease increased operative complexity, the need for multiple percutaneous access tracts and the likelihood of repeat endoscopy. Despite the altered anatomy percutaneous nephrolithotomy was a safe, efficacious approach for autosomal dominant polycystic kidney disease. At last followup there was no stone recurrence and renal function was stable.