Mathew D. Sorensen

Fournier’s Gangrene: Population Based Epidemiology and Outcomes

PURPOSE Case series have shown a Fourniers gangrene mortality rate of 20% to 40% with an incidence of as high as 88% in some studies. Because to our knowledge there are no population based data, we used a national database to investigate the epidemiology of Fourniers gangrene. MATERIALS AND METHODS We used the State Inpatient Databases, the largest hospital based database available in the United States, which includes 100% of hospital discharges from participating states. Inpatients diagnosed with Fourniers gangrene (ICD-9 CM 608.83) who underwent genital/perineal débridement or died in the hospital were identified from 13 participating states in 2001 and from 21 in 2004. Population based incidence, regional trends and case fatality rates were estimated. RESULTS We identified 1,641 males and 39 females with Fourniers gangrene. Cases represented less than 0.02% of hospital admissions. The overall incidence was 1.6/100,000 males, which peaked in males who were 50 to 79 years old (3.3/100,000) with the highest rate in the South (1.9/100,000). The overall case fatality rate was 7.5%. Patients with Fourniers gangrene were rarely treated at hospitals (mean +/- SD 0.6 +/- 1.2 per year, median 0, range 0 to 23). Overall 0 to 4 and 5 or greater cases were treated at 66%, 17%, 10%, 4%, 1% and 1% of hospitals, respectively. CONCLUSIONS Patients with Fourniers gangrene are rarely treated at most hospitals. The population based mortality rate of 7.5% was substantially lower than that reported in case series from tertiary care centers.

Analysis of Diagnostic Angiography and Angioembolization in the Acute Management of Renal Trauma Using a National Data Set

PURPOSE To our knowledge data on diagnostic angiography and angioembolization after renal trauma have been limited to single institution series with small numbers. We used the National Trauma Data Bank® to investigate national patterns of diagnostic angiography and angioembolization after blunt and penetrating renal trauma. MATERIALS AND METHODS All renal injuries treated between 2002 and 2007 were identified in the National Trauma Data Bank by Abbreviated Injury Scale codes and converted to American Association for the Surgery of Trauma renal injury grades. Diagnostic angiography and angioembolization were identified by ICD-9 codes and examined. Initial angioembolization was considered a failure if subsequent therapy was needed. Repeat diagnostic angiography was not considered a failure. RESULTS A total of 9,002 renal injuries were available for analysis. A total of 165 patients (2%) underwent diagnostic angiography after renal injury, including 77 (47%) who underwent concomitant angioembolization. Of the patients 78% sustained grade III-V renal injuries. Of the 77 patients with initial angioembolization 68 required successive therapy. Repeat angioembolization was the most common management choice (29% of patients). Secondary angioembolization was durable during the index hospitalization with success in 35 of 36 cases. Successive therapy was required after initial angioembolization for all grade IV and V renal injuries in 48 patients. The overall renal salvage rate was 92%, including 88% for grade IV and V injuries. CONCLUSIONS Successive therapy is common after initial management of renal injury by angioembolization. Close observation is highly recommended after initial angioembolization for grade IV-V renal injuries. National agreement on the use of diagnostic angiography and angioembolization is needed since these procedures may be overused after grade I-III renal injuries.

Gonadoblastoma and Turner Syndrome

PURPOSE The presence of a Y chromosome in the extrascrotal gonad of patients with intersex disorders has been associated with a high risk of GB and, potentially, GCT. Recently, modern sophisticated genotyping has revealed a subgroup of TS cases with a mosaic karyotype expressing a Y chromosome. We sought to evaluate this group of patients and address their risk of gonadoblastoma. MATERIALS AND METHODS We reviewed the records and genotyping of all females newly diagnosed with TS between 1990 and 2002 at Childrens Hospital in Denver. All patients with TS and Y chromosome mosaicism underwent gonadectomy, and the specimens were evaluated for the presence of gonadoblastoma on histological analysis and to identify Y chromosome on genotyping. RESULTS A total of 192 girls with a clinical diagnosis of TS were identified between January 1990 and December 2002. Seven records were unavailable and 19 patients did not have karyotypic analyses available in the hospital charts. Of the remaining 166 patients 67 exhibited mosaic cell lines, of whom 8 had 45,X0/46,XY mosaic pattern and 59 had mosaic patterns without Y chromosomal elements. All 8 patients with Y mosaicism underwent uneventful laparoscopic gonadectomy on an outpatient basis. One patient observed to have bilateral dysgenetic gonads after gonadectomy was excluded from the study. Gonadoblastoma (bilateral 2 patients, unilateral 1) was detected in 3 of 7 patients (43%) with Y mosaicism. CONCLUSIONS In our series 4.8% of evaluable patients with TS carried a 45,X0/46,XY karyotype. Gonadoblastoma can be evident even at an early age in streak gonads with Y mosaicism and may be bilateral. We recommend prophylactic laparoscopic gonadectomy of streak gonads in patients with TS who carry a Y mosaic genotype, because fertility is not an issue, surgical morbidity is minor and there may be a high potential for malignant transformation of gonadoblastomas in this population.

Impact of nutritional factors on incident kidney stone formation: A report from the WHI OS

PURPOSE Increased fluid intake, and decreased dietary sodium and animal protein intake are thought to reduce the risk of kidney stones but the role of calcium intake is controversial. We evaluated the relationship between dietary factors and incident kidney stone formation. MATERIALS AND METHODS Secondary analysis was done of 78,293 women from the prospective WHI OS (Womens Health Initiative Observational Study) with no history of nephrolithiasis who completed the validated food frequency questionnaire. Multivariate logistic regression was used to determine demographic and dietary factors, and supplement use independently associated with incident kidney stones. RESULTS Overall 1,952 women (2.5%) reported an incident kidney stone in 573,575 person-years of followup. The risk of incident kidney stones was decreased by 5% to 28% (p = 0.01) with higher dietary calcium intake and by 13% to 31% (p = 0.002) with higher water intake after adjusting for nephrolithiasis risk factors. Conversely higher dietary sodium intake increased the risk of nephrolithiasis by 11% to 61% (p <0.001) after adjustment with the most pronounced effect in women with the highest intake. Higher body mass index independently increased the risk of incident nephrolithiasis (adjusted OR 1.19-2.01, p <0.001). Animal protein intake was not associated with nephrolithiasis on multivariate analysis. CONCLUSIONS This study adds to the growing evidence underscoring the importance of maintaining adequate fluid and dietary calcium intake. Greater dietary calcium intake significantly decreased the risk of incident kidney stones. In contrast, excess sodium intake increased the risk of incident nephrolithiasis, especially in women with the highest intake. Animal protein intake was not independently associated with nephrolithiasis.

Fournier's Gangrene: Management and Mortality Predictors in a Population Based Study

PURPOSE The Fourniers gangrene literature comes almost exclusively from tertiary referral centers. We used a population based database to evaluate variations in management and outcomes. MATERIALS AND METHODS Inpatients with Fourniers gangrene who underwent surgical débridement or died were identified from select states in the State Inpatient Databases. Multivariate logistic regression analysis was done to evaluate patient and hospital related predictors of mortality. RESULTS We identified 1,641 males with Fourniers gangrene treated at a total of 593 hospitals. At teaching hospitals more Fourniers gangrene cases were treated per year, and more surgical procedures, débridements and supportive care were reported. Patients treated at teaching hospitals had longer length of stay, greater hospital charges and a higher case fatality rate. Patient related predictors of mortality were increasing age (adjusted OR 4.0 to 15.0), Charlson comorbidity index (adjusted OR 1.20 per additional comorbidity), preexisting conditions, ie congestive heart failure (adjusted OR 2.1), renal failure (adjusted OR 3.2) and coagulopathy (adjusted OR 3.4), and hospital admission via transfer (adjusted OR 1.9), after adjusting for hospital factors and Fourniers gangrene experience. Teaching hospitals had higher mortality due primarily to more acutely ill patients (adjusted OR 1.9). Hospitals where more than 1 Fourniers gangrene case per year were treated had 42% to 84% lower mortality after adjusting for patient age, race, Charlson comorbidity index and admission via transfer (p <0.0001). CONCLUSIONS Teaching and nonteaching hospitals differ substantially in the populations, case definitions, and severity and management of Fourniers gangrene. Hospitals where more patients with Fourniers gangrene were treated had lower mortality rates, supporting the rationale for regionalized care for this rare disease.

Comparison of the Learning Curve and Outcomes of Robotic Assisted Pediatric Pyeloplasty

PURPOSE We compared the learning curve and outcomes in children undergoing robotic assisted laparoscopic pyeloplasty during the initiation of a robotic surgery program compared to the benchmark of open pyeloplasty. MATERIALS AND METHODS The records of our first consecutive 33 children undergoing robotic assisted laparoscopic pyeloplasty from 2006 to 2009 were retrospectively reviewed and compared to those of age and gender matched children who underwent open repair done by senior faculty surgeons before the initiation of our robotic surgery program. We compared operative time, complications, postoperative pain, length of stay and surgical success for 2 surgeons who adopted the robotic approach at an academic teaching institution. RESULTS We found no significant differences in length of stay, pain score or surgical success at a median followup of 16 months. The number of complications was similar and they tended to be early and technical in the robotic assisted laparoscopic pyeloplasty group. Overall average operative time was 90 minutes longer (38%) for robotic assisted laparoscopic pyeloplasty (p <0.004). When evaluated chronologically, there was evidence of a learning curve. After 15 to 20 robotic cases overall operative times for robotic assisted laparoscopic cases was consistently within 1 SD of our average open pyeloplasty time with no significant difference in overall operative time (p = 0.23). Of the decrease in overall operative time 70% was due to decreased pyeloplasty time rather than peripheral time. CONCLUSIONS There was similar safety and efficacy with robotic assisted laparoscopic pyeloplasty, although complications tended to be technical and early in our initial experience. Operative time decreased with experience and after 15 to 20 cases it was similar to that of open pyeloplasty with similar outcomes and surgical success.

Selective Arterial Embolization of Angiomyolipomas: A Comparison of Smaller and Larger Embolic Agents

PURPOSE Selective transarterial embolization for renal angiomyolipomas is effective in preventing or limiting hemorrhage and preserving normal parenchyma. Data are insufficient regarding the safety and efficacy of embolic agents. We compared transarterial embolization of angiomyolipomas using embolic agents of different sizes. MATERIALS AND METHODS We performed a retrospective review of all transarterial angiomyolipoma embolizations from 1999 to 2010, and evaluated demographics, procedural data, embolization response and outcomes comparing smaller (less than 150 microns) and larger (more than 150 microns) embolic agents. RESULTS Overall 48 patients underwent 66 embolization procedures for 72 angiomyolipomas. Smaller agents were used more commonly (58%). Age, gender, indications, pre-embolization angiomyolipoma size and prevalence of tuberous sclerosis were similar between the groups. Angiomyolipomas decreased a mean±SD 25%±18% after embolization with no differences between the groups (p=0.24). There were 10 angiomyolipomas that required 14 repeat embolizations (median 14 months). Repeat embolization of the same mass was almost sixfold more likely in those embolized with smaller agents (OR 5.88, 95% CI 1.64-20.8, p=0.002). Complications were similar between the groups, although 2 of 3 patients with acute respiratory distress underwent embolization with smaller agents. Patients with tuberous sclerosis had similar angiomyolipoma size, decrease in angiomyolipoma size, followup, complications and need for repeat embolization. Practice patterns changed regarding embolization agent size during the study period. CONCLUSIONS Angioembolization with larger embolic agents is associated with higher long-term efficacy compared to smaller agents. Due to concerns for serious pulmonary complications, we no longer use agents smaller than 150 microns. Prospective studies are necessary to evaluate the optimal embolization technique to achieve durable outcomes without increasing patient morbidity.

Fragmentation of Urinary Calculi In Vitro by Burst Wave Lithotripsy

PURPOSE We developed a new method of lithotripsy that uses short, broadly focused bursts of ultrasound rather than shock waves to fragment stones. We investigated the characteristics of stone comminution by burst wave lithotripsy in vitro. MATERIALS AND METHODS Artificial and natural stones (mean ± SD size 8.2 ± 3.0 mm, range 5 to 15) were treated with ultrasound bursts using a focused transducer in a water bath. Stones were exposed to bursts with focal pressure amplitude of 6.5 MPa or less at a 200 Hz burst repetition rate until completely fragmented. Ultrasound frequencies of 170, 285 and 800 kHz were applied using 3 transducers, respectively. Time to fragmentation for each stone type was recorded and fragment size distribution was measured by sieving. RESULTS Stones exposed to ultrasound bursts were fragmented at focal pressure amplitudes of 2.8 MPa or greater at 170 kHz. Fractures appeared along the stone surface, resulting in fragments that separated at the surface nearest to the transducer until the stone was disintegrated. All natural and artificial stones were fragmented at the highest focal pressure of 6.5 MPa with a mean treatment duration of 36 seconds for uric acid stones to 14.7 minutes for cystine stones. At a frequency of 170 kHz the largest artificial stone fragments were less than 4 mm. Exposure at 285 and 800 kHz produced only fragments less than 2 mm and less than 1 mm, respectively. CONCLUSIONS Stone comminution with burst wave lithotripsy is feasible as a potential noninvasive treatment method for nephrolithiasis. Adjusting the fundamental ultrasound frequency allows for stone fragment size to be controlled.

Focused Ultrasound to Expel Calculi from the Kidney: Safety and Efficacy of a Clinical Prototype Device

PURPOSE Focused ultrasound has the potential to expel small stones or residual stone fragments from the kidney, or move obstructing stones to a nonobstructing location. We evaluated the efficacy and safety of ultrasonic propulsion in a live porcine model. MATERIALS AND METHODS Calcium oxalate monohydrate kidney stones and laboratory model stones (2 to 8 mm) were ureteroscopically implanted in the renal pelvicalyceal system of 12 kidneys in a total of 8 domestic swine. Transcutaneous ultrasonic propulsion was performed using an HDI C5-2 imaging transducer (ATL/Philips, Bothell, Washington) and the Verasonics® diagnostic ultrasound platform. Successful stone relocation was defined as stone movement from the calyx to the renal pelvis, ureteropelvic junction or proximal ureter. Efficacy and procedure time was determined. Three blinded experts evaluated histological injury to the kidney in the control, sham treatment and treatment arms. RESULTS All 26 stones were observed to move during treatment and 17 (65%) were relocated successfully to the renal pelvis (3), ureteropelvic junction (2) or ureter (12). Average ± SD successful procedure time was 14 ± 8 minutes and a mean of 23 ± 16 ultrasound bursts, each about 1 second in duration, were required. There was no evidence of gross or histological injury to the renal parenchyma in kidneys exposed to 20 bursts (1 second in duration at 33-second intervals) at the same output (2,400 W/cm(2)) used to push stones. CONCLUSIONS Noninvasive transcutaneous ultrasonic propulsion is a safe, effective and time efficient means to relocate calyceal stones to the renal pelvis, ureteropelvic junction or ureter. This technology holds promise as a useful adjunct to surgical management for renal calculi.

A national study of trauma level designation and renal trauma outcomes

PURPOSE We examined the initial management of renal trauma and assessed patterns of management based on hospital trauma level designation. MATERIALS AND METHODS The National Trauma Data Bank is a comprehensive trauma registry with records from hospitals in the United States and Puerto Rico. Renal injuries treated at a member hospital from 2002 to 2007 were identified. We classified initial management as expectant, minimally invasive (angiography, embolization, ureteral stent or nephrostomy) or open surgical management based on ICD-9 procedure codes. The primary outcome was use of secondary therapies. RESULTS Of 3,247,955 trauma injuries in the National Trauma Data Bank 9,002 were renal injuries (0.3%). High grade injuries demonstrated significantly higher rates of definitive success with the first urological intervention at level I trauma centers vs other trauma centers (minimally invasive 52% vs 26%, p <0.001), and were more likely treated successfully with conservative management (89% vs 82%, p <0.001). When adjusting for other known indices of injury severity, and examining low and high grade injuries, level I trauma centers were 90% more likely to offer an initial trial of conservative management (OR 1.90; 95% CI 1.19, 3.05) and had a 30% lower chance of patients requiring multiple procedures (OR 0.70; 95% CI 0.52, 0.95). CONCLUSIONS Following multivariate analysis conservative therapy was more common at level I trauma centers despite the patient population being more severely injured. Initial intervention strategies were also more definitive at level I trauma centers, providing additional support for tiered delivery of trauma care.