Trends in urinary calculi composition from 2005 to 2015: a single tertiary center study.

The goal of this study was to investigate recent changes in stone composition and patient demographics to identify factors influencing stone formation for the purpose of reducing the incidence of urolithiasis and preventing stone recurrence. This retrospective analysis includes patients who underwent percutaneous nephrolithotripsy or ureteroscopy at our institution from 2005 to 2015. Northwestern Medicine Enterprise Data Warehouse was used to retrieve demographic information and stone composition analyses. The composition of mixed stones containing uric acid (UA) and calcium oxalate monohydrate (COM) was analyzed further. Chi-squared tests were used for categorical variables and logistic regression was used to assess trends. From 2005 to 2015, 5268 stones were treated. COM was predominant in 42.2% and only 16.6% were pure. The male/female ratio decreased significantly from 1.8 to 1.08 and patient age increased (p < 0.001) with 45.6% of patients being 60 or older in 2015. Females formed more CO dihydrate (COD; p = 0.008) and struvite (p = 0.001) overall. The incidence of COM (p = 0.007) and UA (p < 0.001) rose significantly in men whereas both sexes saw a decrease in carbonate apatite (CA; p < 0.001). COM increased considerably from 12 to 75% amongst mixed stones with UA over the 11-year span. We concluded that stone formers have become older and more gender-equal. The increase in female patients parallels the increase in female obesity in the US. The rising predominance of COM, including when mixed with UA, and the scarcity of pure stones indicates it may be necessary to develop new approaches to managing and preventing urolithiasis.

Upper Pole Access for Prone Percutaneous Nephrolithotomy: Advantage or Risk?

OBJECTIVE: To analyze the outcomes of upper pole access during percutaneous nephrolithotomy (PCNL), an option pole often avoided due to the concern for pleural injury. METHODS: We retrospectively collected data on patients undergoing PCNL at our institution. Patients were divided into 3 groups according to access: supracostal upper calyx (group 1), subcostal upper calyx (group 2), and nonupper calyx (group 3). Preoperative imaging was reviewed to assess stone burden, Hounsfield units (HU), location, and Guy's Stone Score. Patients were considered stone-free if residual fragments were 3 mm or smaller on CT scan. RESULTS: We analyzed 329 PCNLs (left: 174; right: 155). Stones had a median size of 32 mm, 800 HU, and Guy's Stone Score of 2. Groups 1, 2, and 3 had 119, 108, and 102 patients, respectively. The 90-day complication rate was 20.4% (7.9% Clavien 3-4). Group 1 patients, with higher BMI and larger stones, had higher SFR than group 3 (89.9% vs 79.4%, P = .038), but with a significantly higher risk of complications (P = .001). Within group 1, left PCNL (7.0% vs 24.2%, P = .016) and BMI ≥30 (6.9% vs 25.0%, P = .013) carried a lower risk of chest tube insertion. There was no difference in complications between groups 2 and 3 (1.9% vs 2.9%). CONCLUSION: Upper pole access is safe and effective, particularly if done below the ribs. Supracostal access is an effective option to achieve higher stone-free rates in complex stones, while carrying a risk of significant hydrothorax, particularly on the right side and in nonobese patients.