Abstracts from the New England Section of the AUA 2021

NE-AUA 2021 Abstracts Scientific Session II: Stones I 20 Pre-operative Urinary Evaluation Prior to Ureteroscopy and Post-operative Infection Rates Daniel C. Leslie, PhD , Liz B. Wang, MD, Shaun E. Wason, MD, David S. Wang, MD Boston University School of Medicine, Boston, MA, USA Introduction: Current AUA guidelines strongly recommend obtaining a urinalysis in all patients and urine culture in patients with suspected UTI or recurrent UTIs prior to ureteroscopy. Prior studies report positive urine culture results in 7.0 to 49.6 % of patients prior to ureteroscopy or PCNL for stone disease. We investigate the impact of urine culture results on the development of post-operative infectious complications in patients undergoing ureteroscopy for stone disease. Materials & Methods: We performed a single center retrospective study of patients undergoing ureteroscopy with laser lithotripsy for stone disease between January 2016 and December 2018. We reviewed the post-operative infectious complications (fever, sepsis, pyelonephritis) within 30 days of the procedure. Pre-operative urine culture results were stratified into negative (<10k CFU/mL), mixed flora (20-100k CFU/mL), or positive (>100k CFU/ mL). Pre-operative urinalysis data (bacteria, leukocyte esterase, nitrites) was obtained for patients without pre-operative urine culture results. Results: 762 of 796 patients (96%) had urine culture results collected prior to ureteroscopy. Of those patients, 536 patients (70.3%) had a negative urine culture, 136 patients (17.8%) had mixed flora, and 90 patients (11.8%) had a positive urine culture. Patients were treated with antibiotics prior to the day of surgery in 98% of positive cultures, 31% of mixed flora, and 7% of negative cultures. Urine cultures were collected within 30 days of the procedure in the majority of patients (479 of 667; 71.8%), between 31 and 60 days in 127 patients (19.0%), and more than 60 days in 61 patients (9.1%). Of the 35 patients without urine culture results, 29 patients (83%) had a urinalysis prior to ureteroscopy which was negative for nitrite and leukocyte esterase in 100% and 86% of patients, respectively. Conclusions: A large majority of patients in this single center study were pre-operatively evaluated for the presence of bacteria in urine according to AUA guidelines. Most patients with a positive culture were appropriately treated with pre-operative antibiotics, but there was inconsistency in treating mixed flora with pre-operative antibiotics. Rates of infectious complications were low in all 3 groups ranging from 2.9 to 3.3 %. Association of Urine Findings with Metabolic Syndrome Traits in a Population of Patients with Known Nephrolithiasis Carley Mulligan, MSIII , Kevan Sternberg, MD, Desiree De Waal, RD, John Asplin, MD, Peter Callas, PhD, Virginia Hood, MBBS, MPH University of Vermont, Larner College of Medicine, Burlington, VT, USA Introduction: The odds of nephrolithiasis increase with an increasing number of metabolic syndrome (met-s) traits. An inverse relationship between met-s traits and decreasing urine pH and decreasing ammonium/net acid excretion (NH4/NAE) has been observed in non-stone formers. Uric acid stone formers have been shown to have lower urine pH and lower NH4/NAE than BMI matched controls on a similar diet. We evaluated associations of urine factors from 24-hour urine studies and stone composition with the number of met-s traits in a large cohort of stone-forming patients. Materials &Methods: Aretrospective review of records of patients >18 years with 24 h urine collections from July 2009 to December 2018 was conducted. Patient factors, laboratory values and associated diagnoses were identified within 6 months of urine collection and stone compositionwithin 1 year. Four groups based on the number (0, 1, 2, > 3) of met-s traits (hypertension, obesity, dyslipidemia, diabetes) were evaluated. Trends across the groups were tested using linear contrasts in analysis of variance for continuous variables and linear terms in logistic regression for categorical variables. Results : 1473 unique patients met inclusion criteria (835 with stone composition). Met-s groups were 0=684, 1=425, 2=211, 3 and 4 =153. There were no differences among the groups for urine volume, calcium, or NH4/ eNAE. There was a significant trend (p< 0.001) and decreasing proportion of calcium phosphate stones (p=0.09) and calcium oxalate stones (p=0.01) with an increasing number of met-s traits. Conclusions: Stone forming patients with met-s have a defined pattern of metabolic and dietary risk factors that contribute to an increased risk of stone formation including higher acid excretion, largely the result of higher protein intake, and lower urine pH. We did not find evidence of reduced NH4 excretion as an explanation for the low urine pH in met-s described in previous studies. 19 11