Metabolic assessment in pure struvite stones formers: is it necessary?

BACKGROUND AND OBJECTIVE: Magnesium ammonium phosphate stones (MAP), also known as struvite stones, are associated with urinary infection and impairment of renal unit. The aim of this study is to evaluate the urinary metabolic risk factors for recurrence of renal calculi in patients submitted to nephrectomy due to MAP stones. METHODS: We retrospectively reviewed the charts of patients > 18 years old submitted to total nephrectomy due to pure MAP stones and pure calcium oxalate (CaOx) stones from July 2006 to July 2016. Urinary metabolic parameters were assessed through 24-hour urine exams ≥ 3 months after nephrectomy. Urinary metabolic parameters and new event related to lithiasis were compared. RESULTS: Twenty-eight and 39 patients were included in MAP and CaOx group, respectively. Abnormalities in 24-hour urine samples were similar between groups. Hypercalciuria occurred in 7.1 and 10.3% of patients in MAP and CaOx group, respectively (p = 0.66), whereas hypocitraturia was present in 65.2 and 59.0% of patients with MAP and CaOx group, respectively (p = 0.41). No significant difference in new events was found between MAP and CaOx groups (17.9 vs. 23.1%, respectively; p = 0.60). CONCLUSION: A 24-hour urine evaluation should be offered to patients submitted to nephrectomy due to pure MAP stones in order to detect metabolic risk, improve treatment, and prevent stone recurrence.

Assessment of Residual Stone Fragments After Retrograde Intrarenal Surgery.

OBJECTIVES: To define the most suitable approach to assess residual stone fragments after retrograde intrarenal surgery (RIRS). METHODS: Ninety-two patients (115 renal units) submitted to RIRS for symptomatic kidney stones >5 mm and <20 mm or <15 mm in the lower Calyx diagnosed by noncontrast CT (NCCT) were prospectively studied. Residual fragments were assessed by endoscopic evaluation (END) at the end of the procedure and by NCCT, ultrasonography (US), and kidney, ureter, and bladder radiograph (KUB) on the 90th postoperative day (POD). NCCT was considered the gold standard for the evaluation of residual fragments after RIRS. RESULTS: The 90th POD NCCT resulted in stone-free status in 74.8% (86/115), 0-2 mm in 8.7% (10/115), and >2 mm residual fragments in 16.5% (19/115) renal units. Stone-free status by END at the end of RIRS was coincident with NCCT in 93.0% of the cases (40/43). There were no cases of residual fragments >2 mm on NCCT if END resulted in stone-free status. In all cases where END resulted in residual fragments >2 mm, US proved to be correct according to NCCT. Neither US nor KUB was able to identify residual fragments between 0 and 2 mm. KUB had only 31.6% (6/19) sensitivity to detect residual fragments >2 mm and did not add sensitivity or specificity to US. CONCLUSIONS: In the follow-up imaging after RIRS, we suggest that if END resulted in residual fragments <2 mm, a 90th POD NCCT should be performed. US may be used if END showed fragments >2 mm.

Contemporary Trends of Inpatient Surgical Management of Stone Disease: National Analysis in an Economic Growth Scenario.

PURPOSE: To assess trends in urologic surgical management of upper tract urolithiasis in Brazil over the past 15 years. MATERIALS AND METHODS: The Public Health System of Brazil (SUS) provides health coverage to 47% to 74% of the population. SUS has a longitudinal hospital inpatient database (SIH/SUS). Hospital discharges between January 1,1998 and December 31, 2012 were abstracted from the SIH/SUS. All inpatient hospitalizations for patients of any age with a primary/secondary diagnosis code of N20.x (calculus of kidney or ureter) were abstracted (ICD-9/10). All urolithiasis-related procedure codes were analyzed. The absolute number of procedures/year and the proportion among all techniques were analyzed for Brazil and also separately for the five distinguished regions of the country. Prevalence trends over the studied period were quantified by the estimated annual percent change (EAPC) using the least squares linear regression methodology. Significance was set at P<0.05. RESULTS: The number of surgical interventions for stone disease increased significantly from 10080 to 24713 (+145%; EAPC=1008.1; P<0.001). The most common surgical modalities in 1998 were nephrectomy (n=2918; 29%), ureterolithotomy (n=2361; 23%), and pyelolithotomy (n=1771; 18%). In 2012, ureteroscopy (URS) was the most commonly performed procedure (n=8725; 35%), followed by ureterolithotomy (n=5822; 24%), and nephrectomy (n=3466; 14%). Between 1998 and 2012, percutaneous nephrolithotomy had the highest significant relative increase (+791.8%; EAPC=0.6%; P<0.001), followed by URS (+607%; EAPC=1.78%; P<0.001). Pyelolithotomy showed the most significant decrease (-47.5%; EAPC = -0.91%; P<0.001). All five regions presented a significant positive increase in the EAPC (P<0.001). CONCLUSION: Trends of stone disease surgical management in the public health system of Brazil follow worldwide tendencies toward less invasive treatment modalities.