Linear relationship between absorbed radiation dose and pulse rate during fluoroscopy.

PURPOSE: To identify the relationship between fluoroscopy pulse rate and absorbed radiation dose. We compared absorbed radiation dose with common proxy measurements such as fluoroscopy time and C-arm reported dose. METHODS: Using a simulated patient model, 60 s fluoroscopy exposures were performed using pulse rates of 30, 8, 4, 2, and 1 pulse(s) per second. Each experiment was performed with both standard and low-dose settings using a GE OEC 9800 plus C-arm. Landauer nanoDot™ OSL dosimeters were used to measure the absorbed radiation dose. RESULTS: Fluoroscopy pulse rate and absorbed radiation dose demonstrated a linear correlation for both standard (R2 = 0.995, p < 0.001) and low-dose (R2 = 0.998, p < 0.001) settings. For any given pulse rate, using the low-dose setting reduced absorbed radiation dose by 58 ± 2.8%. Fluoroscopy time demonstrated a linear relationship with absorbed radiation dose for both standard (R2 = 0.996, p < 0.001) and low-dose (R2 = 0.991, p < 0.001) settings, but did not change with use of the low-dose setting. C-arm reported radiation dose correlated linearly with absorbed dose (R2 = 0.999) but consistently under-estimated measured values by an average of 49 ± 3.5%. Using a combination of 1 pulse-per-second and low-dose fluoroscopy, absorbed dose was reduced by 97.7 ± 0.1% compared to standard dose and 30 pulse-per-second settings. CONCLUSION: Absorbed radiation dose decreases linearly with fluoroscopy pulse rate during equivalent exposure times. Adjusting fluoroscopy pulse rate and utilizing low-dose settings significantly reduces overall absorbed radiation exposure by up to 98%.

Strong Conflict of Interest Policies are not Associated With Decreased Industry Payments to Academic Urology Departments.

OBJECTIVE: To identify whether institutions with strong conflicts of interest (COI) policies receive less industry payments than those with weaker policies. While industry-physician interactions can have collaborative benefits, financial COI can undermine preservation of the integrity of professional judgment and public trust. To address this concern, academic institutions have adopted COI policies. It is unclear whether the strength of COI policy correlates with industry payments in urology. MATERIALS AND METHODS: 131 US academic urology programs were surveyed on their COI policies, and graded according to the American Medical Student Association (AMSA) criteria. Strength of COI policy was compared against industry payments in the Center for Medicare and Medicaid Services Open Payments database. RESULTS: Fifty-seven programs responded to the survey, for a total response rate of 44%. There was no difference between COI policy groups on total hospital payments (P = .05), total department payments (P = .28), or dollars per payment (P = .57). On correlation analysis, there was a weak but statistically nonsignificant correlation between AMSA Industry Policy Survey Score and Open Payments payments (ρ = -0.14, P = .32). CONCLUSION: Strength of conflicts of interest policy in academic urology did not correlate to industry payments within the Open Payments database. Establishment of strong COI policy may create offsetting factors that mitigate the intended effects of the policy. Further studies will be required to develop the evidence base for policy design and implementation across various specialties.

Prolonged nonobstructive urinary retention induced by tibial nerve stimulation in cats.

Nonobstructive urinary retention (NOUR) is a medical condition without an effective drug treatment, but few basic science studies have focused on this condition. In α-chloralose-anesthetized cats, the bladder was cannulated via the dome and infused with saline to induce voiding that could occur without urethral outlet obstruction. A nerve cuff electrode was implanted for tibial nerve stimulation (TNS). The threshold (T) intensity for TNS to induce toe twitch was determined initially. Repeated (6 times) application of 30-min TNS (5 Hz, 0.2 ms, 4-6T) significantly (P < 0.05) increased bladder capacity to 180% of control and reduced the duration of the micturition contraction to 30% of control with a small decrease in contraction amplitude (80% of control), which resulted in urinary retention with a low-voiding efficiency of 30% and a large amount of residual volume equivalent to 130% of control bladder capacity. This NOUR condition persisted for >2 h after the end of repeated TNS. However, lower frequency TNS (1 Hz, 0.2 ms, 4T) applied during voiding partially reversed the NOUR by significantly (P < 0.05) increasing voiding efficiency to 60% and reducing residual volume to 70% of control bladder capacity without changing bladder capacity. These results revealed that tibial nerve afferent input can activate either an excitatory or an inhibitory central nervous system mechanism depending on afferent firing frequencies (1 vs. 5 Hz). This study established the first NOUR animal model that will be useful for basic science research aimed at developing new treatments for NOUR.

Evaluation of the Risks and Benefits of Computed Tomography Urography for Assessment of Gross Hematuria.

OBJECTIVE: To model the risk of radiation-induced malignancy from computed tomography urography (CTU) in evaluation of gross hematuria and contrast this with the benefits of urinary tract cancer detection when compared to renal ultrasound. METHODS: A PUBMED-based literature search was performed to identify model inputs. Estimates of radiation-induced malignancy rates were obtained from the Biological Effects of Ionizing Radiation VII report with dose extrapolation using the linear no-threshold model. RESULTS: Male gender and age over 50 years were associated with a relative risk of upper tract malignancy of 2.04 and 2.95, respectively. The risk of upper tract malignancy missed by renal ultrasound ranged from 0.055% in females under 50 to 0.51% in males over 50. Risk of CTU-induced malignancy with associated loss of life expectancy ranged from 0.25% and 0.027 years in females under 50 to 0.08% and 0.0054 years in males over 50. For CTU to be superior to renal ultrasound, an undiagnosed upper tract malignancy would have to carry a loss of life expectancy of 49.2 years in females under 50, 13.4 years in males under 50, 2.6 years in females over 50, and 1.1 years in males over 50. CONCLUSION: In low-risk patients, CTU for evaluation of gross hematuria may carry a significant risk of radiation-induced secondary malignancy relative to the diagnostic benefit offered over renal ultrasound.

Radiation Mitigation Techniques in Kidney Stone Management.

Patients with nephrolithiasis are exposed to significant quantities of ionizing radiation with the potential to cause secondary malignancy. This risk is magnified by the high recurrence rate of nephrolithiasis. In this article, we identify the risks of ionizing radiation as they pertain to patients with nephrolithiasis. We then identify evidence-based techniques for mitigating patient radiation exposure in the preoperative, intraoperative, and postoperative settings. Key factors include limiting the use of computed tomographic imaging, appropriate modulation of fluoroscopy settings, and minimizing rates of stone recurrence.

Modeling the Incidence of Secondary Malignancy Related to Ionizing Radiation Use in the Management of Nephrolithiasis.

OBJECTIVE: To model the risk of secondary malignancy and associated mortality due to ionizing radiation from the evaluation and management of nephrolithiasis. METHODS: A PUBMED-based literature search was performed to identify model inputs, specifically annual incidence of nephrolithiasis sub-stratified by age and gender and radiation exposure associated with nephrolithiasis episodes. Estimates of age and gender specific radiation-induced malignancy and mortality rates were obtained from the BEIR VII Phase 2 report with dose extrapolation using the linear no-threshold model. RESULTS: Incidence of new diagnoses of nephrolithiasis ranged from 42/100,000 in males 20-30 years old to 248/100,000 in males 60-70 years old. Radiation exposure per nephrolithiasis episode was 37.3 mSv over a 2-year period. Data regarding average stone episodes per patient with nephrolithiasis was limited and conservatively estimated at 1.5. Modeled lifetime attributable risk of secondary malignancy and subsequent mortality in individual stone patients ranged from 0.096% and 0.085%, respectively, in males over the age of 70 to 0.59% and 0.39% in females 20-30 years old. In the USA, overall incidence of secondary malignancy and associated mortality related to nephrolithiasis management was calculated to be 862.7 and 545.3 cases/year, respectively. CONCLUSION: This model suggests that ionizing radiation from the management of nephrolithiasis carries a small but significant risk of causing secondary malignancy. This knowledge must be considered when using modalities that involve radiation in the diagnosis and therapeutic management of nephrolithiasis.

Outcomes of Endourologic Interventions in Patients with Preoperative Funguria.

Introduction: Funguria is encountered in 1% to 5% of cultured urine specimens and may be a result of specimen contamination, colonization, or invasive infection. The characteristics and outcomes of patients with funguria undergoing endourologic intervention have not been evaluated. Materials and Methods: Patients with preoperative funguria undergoing endourologic intervention were retrospectively identified. Preoperative funguria was defined as a urine culture containing >10,000 colony forming units of fungus within 30 days of the operative intervention. Univariable and multivariable regression was performed to identify predictors of postoperative systemic inflammatory response syndrome (SIRS). Results: A total of 65 patients with preoperative funguria were identified, of whom 49 (75.4%) underwent ureteroscopy and 16 (24.6%) underwent percutaneous nephrolithotomy. Average patient age was 55.1 ± 18.3 years, body mass index was 31.8 ± 11.0, and Charlson comorbidity index was 2.52 ± 2.0. Twenty-three patients (35.4%) carried a diagnosis of neurogenic bladder, of whom 18 (27.7%) required indwelling or intermittent catheterization. In total 57 patients (87.7%) had been exposed to antibiotics in the 3 months before intervention. Eighteen (27.7%) patients met SIRS criteria postoperatively, of whom 11 (16.9%) required intensive care unit (ICU) admission. Three (4.6%) and two (3.1%) patients developed postoperative fungemia and bacteremia, respectively. All cases of fungemia were caused by Candida glabrata. On univariable analysis, presence of an indwelling catheter (p = 0.009), presence of a known neurological diagnosis (p = 0.02), presence of C. glabrata on preoperative culture (p = 0.04), and longer operative time (p = 0.04) were predictive of development of postoperative SIRS. No significant predictors were identified on multivariable analysis. Conclusions: Patients with preoperative funguria have high rates of comorbid illness, urinary catheterization, and recent exposure to antibiotics. This patient population is at high risk of perioperative infectious complications after endourologic intervention.

Sympathetic afferents in the hypogastric nerve facilitate nociceptive bladder activity in cats.

This study in α-chloralose-anesthetized cats revealed a role of hypogastric nerve afferent axons in nociceptive bladder activity induced by bladder irritation using 0.25% acetic acid (AA). In cats with intact hypogastric and pelvic nerves, AA irritation significantly ( P < 0.05) reduced bladder capacity to 45.0 ± 5.7% of the control capacity measured during a saline cystometrogram (CMG). In cats with the hypogastric nerves transected bilaterally, AA irritation also significantly ( P < 0.05) reduced bladder capacity, but the change was significantly smaller (capacity reduced to 71.5 ± 10.6% of saline control, P < 0.05) than that in cats with an intact hypogastric nerve. However, application of hypogastric nerve stimulation (HGNS: 20 Hz, 0.2 ms pulse width) to the central end of the transected nerves at an intensity (16 V) strong enough to activate C-fiber afferent axons facilitated the effect of AA irritation and further ( P < 0.05) reduced bladder capacity to 48.4 ± 7.4% of the saline control. This facilitation by HGNS was effective only at selected frequencies (1, 20, and 30 Hz) when the stimulation intensity was above the threshold for activating C-fibers. Tramadol (an analgesic agent) at 3 mg/kg iv completely blocked the nociceptive bladder activity and eliminated the facilitation by HGNS. HGNS did not alter non-nociceptive bladder activity induced by saline distention of the bladder. These results indicate that sympathetic afferents in the hypogastric nerve play an important role in the facilitation of the nociceptive bladder activity induced by bladder irritation that activates the silent C-fibers in the pelvic nerve.

Spinal interneuronal mechanisms underlying pudendal and tibial neuromodulation of bladder function in cats.

This study examined the mechanisms underlying pudendal and tibial neuromodulation of bladder function at the single neuron level in the spinal cord. A microelectrode was inserted into the S2 spinal cord of anesthetized cats to record single neuron activity induced by bladder distention over a range of constant intravesical pressures (10-40 cmH2O). Pudendal nerve stimulation (PNS) or tibial nerve stimulation (TNS) was applied at 5 Hz frequency and 0.2 ms pulse width and at multiples of the threshold (T) intensities for inducing anal or toe twitches. A total of 14 spinal neurons from 11 cats were investigated. Both PNS and TNS at 2 T intensity significantly (p < .05) reduced by 40-50% the frequency of firing induced by bladder distention at 20-40 cmH2O in the same spinal neurons. This reduction was not changed by blocking opioid receptors with naloxone (1 mg/kg, i.v.). Activation of pudendal afferents by repeatedly stroking (3-5 times per second) the genital skin using a cotton swab also inhibited the neuron activity induced by bladder distention. Prolonged (30 min) TNS at 4 T intensity produced a short lasting (10-18 min) post-stimulation inhibition that reduced by 40-50% bladder-related neuron activity at different bladder pressures. These results indicate that PNS and TNS inhibition of reflex bladder activity may be mediated in part by convergence of inhibitory inputs onto the same population of bladder-related interneurons in laminae V-VII of the S2 spinal cord and that an opioid receptor mechanism is not involved in the inhibition.

Cowper's Gland Syringocele.

Cowper's gland syringoceles are rare cystic dilations of the Cowper's gland duct. They are typically diagnosed in childhood but occasionally occur in adults. We report the case of a 28-year-old man who presented with a painful perineal and inferior scrotal mass and was found to have a large Cowper's gland syringocele extending into the scrotum associated with a scrotal abscess. Treatment consisted of surgical excision. The magnetic resonance imaging findings of this case are described.

Risk of Radiation from Computerized Tomography Urography in the Evaluation of Asymptomatic Microscopic Hematuria.

PURPOSE: The AUA (American Urological Association) guidelines for asymptomatic microscopic hematuria recommend that patients undergo computerized tomography urography, which is associated with high doses of ionizing radiation. To our knowledge the associated risk of secondary malignancy and mortality remains unknown. We modeled the risk of malignancy and associated mortality due to ionizing radiation from computerized tomography urography relative to the additional diagnostic benefit offered over renal ultrasound. MATERIALS AND METHODS: We performed a PubMed® based literature search to identify model inputs. We obtained estimates of age and gender specific radiation induced secondary malignancy and mortality rates from the BEIR (Biologic Effects of Ionizing Radiation) VII Phase 2 report with dose extrapolation using the linear no threshold model. RESULTS: Patients with asymptomatic microscopic hematuria had a 0.053% and 0.48% prevalence of upper tract urothelial carcinoma and renal cell carcinoma, respectively. Ultrasound had 77% sensitivity for upper tract urothelial carcinoma and 82% sensitivity for renal cell carcinoma. The effective radiation dose of computerized tomography urography was 31.7 mSv. Based on these inputs a population of 100,000 patients with asymptomatic microscopic hematuria would include 53.1 and 478 patients with upper tract urothelial carcinoma and renal cell carcinoma, respectively. On ultrasound alone 98.2 cases of upper urinary tract malignancy would be missed. An additional 149 cases of secondary malignancy would be caused by computerized tomography urography associated radiation with 101 fatalities. A total of 1,018.3 computerized tomography urography studies would need to be performed to detect an additional case of upper tract malignancy. CONCLUSIONS: Based on current risk models computerized tomography urography for asymptomatic microscopic hematuria may be associated with a small but significant risk of secondary malignancy relative to the additional diagnostic benefit offered.

Identifying and managing the risks of medical ionizing radiation in endourology.

INTRODUCTION: The risks of exposure to medical ionizing radiation is of increasing concern both among medical professionals and the general public. Patients with nephrolithiasis are exposed to high levels of ionizing radiation through both diagnostic and therapeutic modalities. Endourologists who perform a high-volume of fluoroscopy guided procedures are also exposed to significant quantities of ionizing radiation. The combination of judicious use of radiation-based imaging modalities, application of new imaging techniques such as ultra-low dose computed tomography (CT) scan, and modifying use of current technology such as increasing ultrasound and pulsed fluoroscopy utilization offers the possibility of significantly reducing radiation exposure. We present a review of the literature regarding the risks of medical ionizing radiation to patients and surgeons as it pertains to the field of endourology and interventions that can be performed to limit this exposure. MATERIALS AND METHODS: A review of the current state of the literature was performed using MEDLINE and PubMed. Interventions designed to limit patient and surgeon radiation exposure were identified and analyzed. Summaries of the data were compiled and synthesized in the body of the text. RESULTS: While no level 1 evidence exists demonstrating the risk of secondary malignancy with radiation exposure, the preponderance of evidence suggests a dose and age dependent increase in malignancy risk from ionizing radiation. Patients with nephrolithiasis were exposed to an average effective dose of 37mSv over a 2 year period. Multiple evidence-based interventions to limit patient and surgeon radiation exposure and associated risk were identified. CONCLUSION: Current evidence suggest an age and dose dependent risk of secondary malignancy from ionizing radiation. Urologists must act in accordance with ALARA principles to safely manage nephrolithiasis while minimizing radiation exposure.

Direction of Rotation in Testicular Torsion and Identification of Predictors of Testicular Salvage.

OBJECTIVES: To identify the rate at which testicular torsion occurs in a lateral direction and identify any predictors of direction of testicular rotation and orchiectomy. MATERIALS AND METHODS: We performed a retrospective review of 104 cases of emergent scrotal exploration performed for testicular torsion by 3 pediatric urologists from 2003 to 2017. Patients with neonatal torsion, negative scrotal exploration, or exploration for presumed intermittent testicular torsion were excluded. Univariable logistic regression was performed to assess if any factors predicted direction of testicular rotation. Univariable and multivariable logistic regression was used to identify predictors of testicular salvage. RESULTS: Of 104 cases of acute testicular torsion, information regarding the direction of testicular rotation was available in 81 patients. Lateral testicular rotation occurred in 38 cases (46%). No factors were found to be predictive of direction of torsion. Orchiectomy for testicular nonviability was performed in 50 of 104 cases (48%). On univariable analysis, younger age (p = .002), absence of gastrointestinal symptoms (P = .02), time to exploration (P < .001), testicular size differential on ultrasound (p = .002), absence of hydrocele (P = .01), abnormal ultrasound echotexture (P < .001), and degree of torsion (P = .04) were associated with orchiectomy. With the exception of absence of gastrointestinal symptoms, all predictors of orchiectomy remained statistically significant on multivariable analysis. CONCLUSION: Testicular rotation occurs in a lateral direction in 46% of cases. Lateral manual detorsion should be performed only with awareness of the potential for increasing the degree of testicular rotation. New independent predictors of testicular salvage were identified.

Single Pulse-per-second Setting Reduces Fluoroscopy Time During Ureteroscopy.

OBJECTIVE: To evaluate the effect of 1 pulse-per-second (pps) fluoroscopy on fluoroscopy time and surgeon radiation exposure during ureteroscopy. MATERIALS AND METHODS: A retrospective review of a single endourologist's operative records was performed over a 12-month period. Adult patients undergoing ureteroscopy were included. At the 6-month point, the switch from continuous "low-dose" to 1 pps "low-dose" fluoroscopy was made. Surgeon radiation exposure was measured using 1 dosimeter placed at the torso under the lead apron and 1 dosimeter overlying the chest outside the lead apron. RESULTS: A total of 84 and 70 patients underwent ureteroscopy using continuous and 1 pps fluoroscopy, respectively. No differences were identified between the 2 groups with regard to patient age (P = .96), sex (P = .26), body mass index (P = .95), stone multiplicity (P = .31), bilateral ureteroscopy (P = .07), pre-stenting (P = .99), staged (P = .84) or failed (P = .99) primary ureteroscopy, ureteral access sheath utilization (P = .10), or case duration (P = .54). Patients in the 1 pps cohort had a larger median stone burden (P = .04). The median fluoroscopy time was reduced from 77 (interquartile range: 54-115) to 16 seconds (interquartile range: 13-24) using 1 pps fluoroscopy (P < .001). Monthly surgeon radiation exposure was reduced by 64%, from 6.8 ± 8.3 to 1.8 ± 2.7 mRad deep dose equivalent (P = .11), from 120.6 ± 101.4 to 49.2 ± 66.6 mRad lens dose equivalent (P = .10), and from 116.2 ± 97.8 to 47.6 ± 64.0 mRad shallow dose equivalent (P = .11). Reversion to continuous fluoroscopy was never required during the study period. CONCLUSION: Single pps fluoroscopy is feasible, significantly reduces fluoroscopy time, and lowers surgeon radiation exposure by 64%.

Appearance of Pyelitis Emphysematosa on Computed Tomography.

Pyelitis emphysematosa is a gas-forming infection characterized by gas located within the wall of the collecting system and renal pelvis. There are only 2 reported cases of pyelitis emphysematosa in the literature, neither of which occurred in the era of cross-sectional imaging. Here we present a case of pyelitis emphysematosa occurring in an elderly female with congenital left renal atrophy and chronic right hydronephrosis secondary to ureteropelvic junction obstruction.

Biopsy Perineural Invasion in Prostate Cancer Patients Who Are Candidates for Active Surveillance by Strict and Expanded Criteria.

OBJECTIVE: To evaluate the association of biopsy perineural invasion (PNI) with adverse pathologic findings on radical prostatectomy in patients who would have been candidates for active surveillance (AS). METHODS: Using a prospectively populated database of 3084 men who underwent open radical prostatectomy, candidates for AS by strict (Johns Hopkins) and expanded (University of Toronto) criteria were identified. The presence of adverse pathologic features at radical prostatectomy was compared between those men with and without biopsy PNI. RESULTS: Of 596 men who met strict criteria for AS, 16 (3%) had biopsy PNI. In the strict AS cohort, there were no differences in adverse pathologic features at radical prostatectomy between those with and without PNI. Of 1197 men who were candidates for AS by expanded criteria, 102 (9%) had biopsy PNI. Men with biopsy PNI in the expanded AS cohort were more likely to have extraprostatic extension (P < .001) and pathologic upgrading (P = .01) at prostatectomy. In addition, those with PNI had larger dominant nodules (P < .001), and cancer comprised a greater percentage of their prostate glands (P < .001). There was no difference in the proportion with a positive margin between the 2 groups (P = .77). CONCLUSION: Biopsy PNI was rare in patients who met strict criteria for AS. Among those men who met expanded criteria, PNI was associated with adverse pathologic findings upon prostatectomy. The presence of biopsy PNI may have a role in further risk stratifying patients who meet expanded criteria for AS.

Partial and hemi-nephrectomy for renal malignancy in patients with horseshoe kidney.

INTRODUCTION: Horseshoe kidney is the most common congenital renal fusion anomaly, with an estimated incidence of 1.7 to 2.5 cases per 1000 live births. In these patients, nephron-sparing surgical management of renal tumors may be complicated by abnormal renal location, aberrant vasculature, and the presence of a renal isthmus. We present the largest known series of patients with renal malignancy in horseshoe kidneys managed by partial or hemi-nephrectomy with associated outcomes. MATERIALS AND METHODS: A retrospective review of our institution's electronic medical record was conducted to identify consecutive cases over an 11 year period. Pediatric patients and those who underwent surgery for benign indications were excluded from analysis. RESULTS: Eight patients with horseshoe kidney who underwent partial or hemi-nephrectomy for renal malignancy were identified. Median tumor size was 6.0 cm (IQR 3.7 cm-9.5 cm). Six patients had clear cell renal cell carcinoma (RCC), 1 patient had papillary RCC, and 1 patient had a renal carcinoid tumor with concurrent adenocarcinoma. Median length of stay was 4 days (IQR 2-.5.5 days). Median perioperative change in eGFR was -6 mL/min/1.73² (IQR -2.6-8.6 mL/min/1.73m²). One patient developed postoperative urine leak requiring percutaneous drainage and ureteral stent placement. Median follow up was 38.5 months, with a cancer-specific survival of 87.5% and an overall survival of 62.5%. CONCLUSION: Partial and hemi-nephrectomy for renal malignancy can safely be performed in patients with horseshoe kidney with acceptable operative and oncologic outcomes.