Jessica E. Paonessa

Preoperative Bladder Urine Culture as a Predictor of Intraoperative Stone Culture Results: Clinical Implications and Relationship to Stone Composition

PURPOSE We examine the relationship between urine and stone cultures in a large cohort of patients undergoing percutaneous stone removal and compare the findings in infectious vs metabolic calculi. MATERIALS AND METHODS A total of 776 patients treated with percutaneous nephrolithotomy who had preoperative urine cultures and intraoperative stone cultures were included in the study. Statistical analysis used chi-square or logistic fit analysis as appropriate. RESULTS Preoperative urine culture was positive in 352 patients (45.4%) and stone cultures were positive in 300 patients (38.7%). There were 75 patients (9.7%) with negative preoperative cultures who had positive stone cultures, and in patients with both cultures positive the organisms differed in 103 (13.3%). Gram-positive organisms predominated in preoperative urine and stone cultures. CONCLUSIONS Preoperative urine cultures in patients undergoing percutaneous nephrolithotomy are unreliable as there is a discordance with intraoperative stone cultures in almost a quarter of cases. There has been a notable shift toward gram-positive organisms in this cohort of patients.

Nephrocalcinosis in Calcium Stone Formers Who Do Not have Systemic Disease

PURPOSE Nephrocalcinosis is commonly present in primary hyperparathyroidism, distal renal tubular acidosis and medullary sponge kidney disease. To our knowledge it has not been studied in patients with calcium phosphate stones who do not have systemic disease. MATERIALS AND METHODS We studied patients undergoing percutaneous nephrolithotomy who had calcium phosphate or calcium oxalate stones and did not have hyperparathyroidism, distal renal tubular acidosis or medullary sponge kidney disease. On postoperative day 1 all patients underwent noncontrast computerized tomography. If there were no residual calcifications, the patient was categorized as not having nephrocalcinosis. If there were residual calcifications, the patient underwent secondary percutaneous nephrolithotomy. If the calcifications were found to be stones, the patient was categorized as not having nephrocalcinosis. If the calcifications were not stones, the patient was categorized as having nephrocalcinosis. Patients were grouped based on the type of stones that formed, including hydroxyapatite, brushite and idiopathic calcium oxalate. The extent of nephrocalcinosis was quantified as 0--absent nephrocalcinosis to 3--extensive nephrocalcinosis. Patients with residual calcifications on postoperative day 1 noncontrast computerized tomography who did not undergo secondary percutaneous nephrolithotomy were excluded from analysis. The presence or absence of nephrocalcinosis was correlated with metabolic studies. RESULTS A total of 67 patients were studied, including 14 with hydroxyapatite, 19 with brushite and 34 with idiopathic calcium oxalate calculi. Nephrocalcinosis was present in 10 of 14 (71.4%), 11 of 19 (57.9%) and 6 of 34 patients (17.6%) in the hydroxyapatite, brushite and idiopathic calcium oxalate groups, respectively (chi-square p = 0.01). The mean extent of nephrocalcinosis per group was 1.98, 1.32 and 0.18 for hydroxyapatite, brushite and idiopathic calcium oxalate, respectively (p ≤0.001). The presence of nephrocalcinosis positively correlated with urine calcium excretion (mean ± SD 287.39 ± 112.49 vs 223.68 ± 100.67 mg per day, p = 0.03). CONCLUSIONS Patients without systemic disease who form hydroxyapatite and brushite stones commonly have coexistent nephrocalcinosis. Nephrocalcinosis can occur in calcium oxalate stone formers but the quantity and frequency of nephrocalcinosis in this group are dramatically less.

Extracorporeal Shock Wave Lithotripsy: Generators and Treatment Techniques

Extracorporeal shock-wave lithotripsy has been proposed a s a modality to facilitate the removal of bone cement during revision arthroplasty; however, concomitant cortical microfractures have been reported. The current study examines the effect on whole bone strength of extracorporeal shock-wave lithotripsy directed a t the cementbone complex. Canine femora were subjected to manual cement extraction or lithotripsy followed by manual cement extraction. Contralateral femora served as controls. Torsional fractures were created, and maximum torque, maximum angular displacement, and energy capacity to failure were determined. Although cement extraction alone reduced mean torque by 6.6% and failed to reduce mean torque angle or mean energy capacity, the combination of lithotripsy and cement extraction reduced mean torque by 7.3470, mean torque angle by 14.3%, and mean energy capacity by 18.3%. No statistical significance was demonstrated between the two groups in torque, angle, or energy capacity. At magnitudes and numbers of shock waves previously shown to significant11 reduce cement-bone interface mechanical strength, lithotripsy exposure had a minimal and insignificant effect on whole bone strength.

Sensitivity of Noncontrast Computed Tomography for Small Renal Calculi With Endoscopy as the Gold Standard

OBJECTIVE To compare the sensitivity of noncontrast computed tomography (CT) with endoscopy for detection of renal calculi. Imaging modalities for detection of nephrolithiasis have centered on abdominal x-ray, ultrasound, and noncontrast CT. Sensitivities of 58%-62% (abdominal x-ray), 45% (ultrasound), and 95%-100% (CT) have been previously reported. However, these results have never been correlated with endoscopic findings. METHODS Idiopathic calcium oxalate stone formers with symptomatic calculi requiring ureteroscopy were studied. At the time of surgery, the number and the location of all calculi within the kidney were recorded followed by basket retrieval. Each calculus was measured and sent for micro-CT and infrared spectrophotometry. All CT scans were reviewed by the same genitourinary radiologist who was blinded to the endoscopic findings. The radiologist reported on the number, location, and size of each calculus. RESULTS Eighteen renal units were studied in 11 patients. Average time from CT scan to ureteroscopy was 28.6 days. The mean number of calculi identified per kidney was 9.2 ± 6.1 for endoscopy and 5.9 ± 4.1 for CT (P <.004). The mean size of total renal calculi (sum of the longest stone diameters) per kidney was 22.4 ± 17.1 mm and 18.2 ± 13.2 mm for endoscopy and CT, respectively (P = .06). CONCLUSION CT scan underreports the number of renal calculi, probably missing some small stones and being unable to distinguish those lying in close proximity to one another. However, the total stone burden seen by CT is, on average, accurate when compared with that found on endoscopic examination.

MP27-04 GIVING UNDERACTIVE BLADDERS A SECOND CHANCE: HOLMIUM LASER ENUCLEATION OF THE PROSTATE FOR MANAGEMENT OF LOWER URINARY TRACT SYMPTOMS IN PATIENTS WITH DETRUSOR UNDERACTIVITY.

as UUI. We assessed whether the quantification of urodynamic DO can improve the prediction of post-operative UUI following the HoLEP in patients with benign prostatic hyperplasia. METHODS: We prospectively measured the filling volume at DO (Vol_DO), detrusor pressure at DO (PdetDO), and presence or absence of DO incontinence, in addition to the ICS recommendations for urodynamic study (UDS) in 105 patients who underwent HoLEP between May 2010 and September 2015. RESULTS: Mean age ( SD) and prostate volume were 71.1 ( 7.0) years and 63.7 ( 24.2) mL. Of the 105 patients, 10 (9.5%) patients experienced the UUI at post-operative 3 months. The UUI-positive group demonstrated higher international prostate symptom score (IPSS)-storage (11.4 vs. 7.5, p1⁄40.004) than the UUI-negative group. However, other parameters such as age, prostate size, preoperative uroflometry findings, IPSS-emptying, and IPSS-QoL were not significantly different between two groups (p range, 0.062-0.797). On UDS findings, UUI-positive group showed higher PdetDO than UUI-negative group (100.4 vs. 54.7 cmH2O, p1⁄40.008). However, rates of DO presence and DO_vol were not significantly different between two groups (p-value, 0.423 and 0.788). DO incontinence is more frequent in UUI-positive group than in UUI-negative group, but failed to reach the statistical significance (80.0 vs. 52.6%, p1⁄40.098). Spline curve analysis results suggested the optimal cut-off value of PdetDO for increased risk of UUI as 108.0 cmH2O (Figure). Our multivariate analysis revealed that pre-operative IPSS-storage (OR1⁄41.696, p1⁄40.036) and PdetDO ( 108.0 cmH2O; OR1⁄415.546, p1⁄40.044) were independent predictive factors for UUI after HoLEP. CONCLUSIONS: Quantification of urodynamic DO improved the prediction of UUI after HoLEP