Glenn M Cannon

Childrens Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States

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Publications (41)102.3 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Circumcision is the most common surgical procedure in males in the United States, and minor complications are not uncommon. Major complications like partial penile amputations have been reported with successful replantation. Complete penile amputations in adult males have been described, and successful replantation has been reported with increasing success. We report a case of complete penile amputation at the penopubic junction using a Mogen clamp in a 7-day-old neonate with replantation using postoperative leech therapy. To our knowledge this is the first time leech therapy has been used postoperatively for neonatal penile amputation.
    Urology 06/2014; · 2.42 Impact Factor
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    ABSTRACT: We sought to determine which pediatric patients sustaining blunt grade IV renal trauma are at highest risk for failing non-operative management and in what time frame those patients will likely present. We retrospectively reviewed children with non-vascular grade IV blunt renal trauma between 2003-2012. We compared characteristics on computerized tomography, reasons for intervention, type of and timing of surgery, length of stay (LOS) and need for readmission between patients undergoing early intervention (<72 hours after admission) versus patients in whom conservative management was attempted, with any interventions occurring >72 hours after admission. Twenty-six children were identified with non-vascular grade 4 blunt renal trauma. Conservative management was attempted on 16 (62%) patients. Seven (44%) of these patients required intervention (ureteral stent and/or percutaneous drain placement) with a mean time to intervention of 11 days. Collecting system clot and larger urinoma (1.45cm vs 4.29cm) significantly predicted failure of conservative management (P<0.05). Presence of dissociated renal fragments (57% vs 11%) and interpolar contrast extravasation (57% vs 0%) were more common in the intervention group (P>0.05), as were readmissions (43% vs 0%), mean LOS (7.9 vs 5.4 days) and transfusions (14% vs 0%) (P>0.05). Collecting system hematoma and urinoma size significantly predicted failure of conservative management with a mean time to intervention of 11 days. Patients who failed conservative management had a greater incidence of dissociated renal fragments and interpolar extravasation. Early identification of these children may reduce hospital readmissions, LOS and prolonged morbidity.
    The Journal of urology 02/2014; · 4.02 Impact Factor
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    ABSTRACT: A 10-year-old boy underwent a computed tomography (CT) scan for left flank pain following a fall. Imaging demonstrated a 5 cm left upper pole renal mass. Partial nephrectomy revealed metanephric adenofibroma, a benign stromal-epithelial tumor thought to represent a hyperdifferentiated, mature form of Wilms' tumor. We briefly discuss the histopathology and management of this rare tumor.
    The Canadian Journal of Urology 04/2013; 20(2):6737-8. · 0.74 Impact Factor
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    ABSTRACT: PURPOSE: An increasing percentage of pediatric pyeloplasties are being performed with assistance of the da Vinci® robot. Recent literature reports decreased operative times and length of hospital stays when robotic procedures were performed, but there is little published data comparing the cost of pediatric robotic and pure laparoscopic pyeloplasty. We reviewed a representative sample of pyeloplasties performed at our institution and performed a cost analysis. MATERIALS AND METHODS: We retrospectively identified 23 robotic assisted and 23 laparoscopic pyeloplasties performed at our institution from (August 2008 - April 2012). Total cost was calculated from both direct and indirect costs provided by our billing department. RESULTS: Robotic procedures were shorter than pure laparoscopic procedures (200min vs 265min, P<0.001), but there was no significant difference in the total cost of the two procedures ($15337 vs $16067, P<0.46). When compared to laparoscopic cases, sub group analysis demonstrated decreased operative times (140min vs 265min, P< .00001) and total cost ($11949 vs $16067, P<0.0001) in robotic cases where stents were placed in an antegrade fashion. CONCLUSION: With its widespread use, the cost of robotic instrumentation may decrease and experience may further shorten operative times; however at this time it remains to be seen whether robotic technology will become a cost effective replacement of pure laparoscopy for management of pediatric UPJ obstruction.
    The Journal of urology 09/2012; · 4.02 Impact Factor
  • Glenn M Cannon
    The Journal of urology 08/2012; 188(4 Suppl):1633. · 4.02 Impact Factor
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    ABSTRACT: We report the case of a 12-year-old patient with previously diagnosed Crohn disease who presented with penile edema and purpura, with extension into the scrotum. Subsequent work-up including biopsy led to the diagnosis of extraintestinal Crohn disease, a rare manifestation in the genital region. Prompt treatment with steroids led to complete resolution of both penoscrotal edema and purpura. We describe our case, followed by a discussion of etiologies of penoscrotal edema and purpura as a review for the practicing pediatric urologist.
    Journal of pediatric urology 05/2012; 8(5):e47-50. · 1.38 Impact Factor
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    ABSTRACT: Variant presentations of cloacal exstrophy are exceedingly rare. Historically, genetic males with cloacal extrophy were re-assigned to the female gender due to phallic inadequacy. Early recognition of intravesical phallic structures in cloacal exstrophy cases may impact gender reassignment discussions and long-term gender outcomes. We report the case of a male infant with cloacal exstrophy presenting with an intravesical phallus, review and compare the presenting anatomical features of the three previously reported cases, and discuss the potential impact of these findings on gender reassignment in these complex children.
    Journal of pediatric urology 11/2011; 8(4):426-30. · 1.38 Impact Factor
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    ABSTRACT: Increasingly, patients seek medical information via the Internet, despite highly variable information quality. We sought to determine whether controversial urological topics are associated with decreased content quality or search characteristics. We systematically searched the Internet for 5 noncontroversial (cryptorchidism, testicular torsion, urethral stricture, testicular cancers, renal cancers) and 5 controversial (disorders of sexual differentiation, circumcision, penile elongation, interstitial cystitis, testosterone therapy) conditions. Number of total hits, sponsored links, page owner and author, accreditation, updates, advertising, readability, and content quality were assessed for each topic. Content quality was determined on a 5-point scale for accuracy and completeness of 3 domains: diagnosis, natural history, and treatment. In total, 100 websites were evaluated. Noncontroversial topics had more hits (1,610,000 vs 475,000) and more sponsored links (30% vs 10%) than controversial topics. Noncontroversial web pages were more likely to have government or medical owners (58% vs 30%, P = .009) than controversial web pages. Website quality was significantly different between noncontroversial and controversial topics. In regard to accuracy, noncontroversial topics had higher scores for diagnosis (4.6 vs 3.8, P <.0001), natural history (4.5 vs 3.2, P <.0001), and treatment (4.6 vs 3.3, P <.0001). Similarly, noncontroversial topics had higher completeness scores for diagnosis (3.8 vs 3.0, P = .001), natural history (3.7 vs 3.0, P = .003), and treatment (3.6 vs 3.0, P = .006). Web pages dedicated to controversial urological topics have lower quality content in regard to diagnosis, natural history, and treatment. Such quality issues may contribute to ongoing public confusion and misinformation regarding these challenging topics.
    Urology 09/2011; 78(5):1051-6. · 2.42 Impact Factor
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    ABSTRACT: Contrast-enhanced ultrasound (US) imaging is potentially applicable to the clinical investigation of a wide variety of perfusion disorders. Quantitative analysis of perfusion is not widely performed, and is limited by the fact that data are acquired from a single tissue plane, a situation that is unlikely to accurately reflect global perfusion. Real-time perfusion information from a tissue volume in an experimental rabbit model of testicular torsion was obtained with a two-dimensional matrix phased array US transducer. Contrast-enhanced imaging was performed in 20 rabbits during intravenous infusion of the microbubble contrast agent Definity® before and after unilateral testicular torsion and contralateral orchiopexy. The degree of torsion was 0° in 4 (sham surgery), 180° in 4, 360° in 4, 540° in 4, and 720° in 4. An automated technique was developed to analyze the time history of US image intensity in experimental and control testes. Comparison of mean US intensity rate of change and of ratios between mean US intensity rate of change in experimental and control testes demonstrated good correlation with testicular perfusion and mean perfusion ratios obtained with radiolabeled microspheres, an accepted 'gold standard'. This method is of potential utility in the clinical evaluation of testicular and other organ perfusion.
    Physics in Medicine and Biology 03/2011; 56(7):2183-97. · 2.70 Impact Factor
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    ABSTRACT: In the US, there has been an evolution in the practice of pediatric urology from a primary academic sub-specialty focused on reconstruction of major congenital genitorurinary abnormalities to a mixed academic and private practice that serves as the primary care giver for all pediatric urologic concerns. The estimated manpower needs were unable to be resolved, due to our inability to determine the impact of sub-specialty certification on referral patterns, along with the failure to embrace the use of physician extenders. Here, we review a series of surveys performed in 2006-2010 regarding the sub-specialty of pediatric urology. The four surveys focused on workforce needs, appraised the financial impact of educational debt on the pediatric urology community, and evaluated concerns of the current fellows in training. The median financial income for a pediatric urologist, the resident's educational debt load, and a desire of the fellows to have an open dialog with the urologic community regarding the merits of the research year are revealed. We have identified that the ability to recruit fellows into our field is dependent upon a combination of factors: interest in the field, job availability in relationship to geographic locations, mentoring, concerns regarding financial/familial hardships encountered during a 2-year fellowship, and the lack of increased financial reimbursement for the extra training required.
    Journal of pediatric urology 02/2011; 7(4):446-53. · 1.38 Impact Factor
  • Glenn M. Cannon, Richard S. Lee
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    ABSTRACT: In 1993, Jordan and Winslow described laparoscopic upper pole partial nephrectomy in a 14-year-old girl with bilateral duplicated collecting systems [1]. Since that time, there has been a substantial amount of literature devoted to laparoscopic renal surgery in children. Prior to and including 2009, there have been 28 case series of retroperitoneal laparoscopic nephrectomy [2–29], 26 case series of transperitoneal laparoscopic nephrectomy [2, 11, 28, 30–52], and 3 case series of robotic-assisted laparoscopic nephrectomy [53–55]. Regardless of the approach taken, the literature reveals that laparoscopic renal ablative surgery in children is safe and effective [56]. KeywordsPediatric-Laparoscopic-Robotic-Upper pole-Nephrectomy-Nonfunctioning-Moieties
    12/2010: pages 73-81;
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    ABSTRACT: The optimal method for neovagina creation in patients with vaginal agenesis is controversial. Progressive perineal dilation is a minimally invasive method with high success rates. However, the economic merits of progressive perineal dilation compared to surgical vaginoplasty are unknown. We performed a Markov based cost-effectiveness analysis of 3 management strategies for vaginal agenesis-progressive perineal dilation with and without subsequent vaginoplasty, and up-front vaginoplasty. Cost data were drawn from the Pediatric Health Information System database (2004 to 2009) for inpatient procedures and from governmental cost data (2009) for outpatient procedures and clinical followup. Other model parameters were derived from a systematic literature review and comparison with other congenital and acquired pediatric and/or adolescent gynecologic conditions. Bounded and probabilistic sensitivity analyses were used to assess model stability. Including all procedures, equipment and physician visits, progressive perineal dilation had a mean cost of $796, while vaginoplasty cost $18,520. Up-front vaginoplasty was strongly dominated at any age, ie was more expensive but no more effective than other options. In cases of progressive perineal dilation failure the incremental cost-effectiveness ratio of progressive perineal dilation with subsequent vaginoplasty was $1,564 per quality adjusted life-year. Only the utility weights of life after treatment impacted model outcomes, while frequency of followup and probability of treatment success did not. Initial progressive perineal dilation followed by vaginoplasty in cases of dilation failure is the most cost-effective management strategy for vaginal agenesis. Initial vaginoplasty was less cost-effective than initial progressive perineal dilation in 99.99% of simulations.
    The Journal of urology 11/2010; 184(5):2116-21. · 4.02 Impact Factor
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    ABSTRACT: Currently, gastrointestinal segments are considered the gold standard for bladder reconstructive procedures. However, significant complications including chronic urinary tract infection, metabolic abnormalities, urinary stone formation, bowel dysfunction, and secondary malignancies are associated with this approach. Biomaterials derived from silk fibroin may represent a superior alternative due their robust mechanical properties, biodegradable features, and processing plasticity. In the present study, we evaluated the efficacy of a gel spun silk-based matrix for bladder augmentation in a murine model. Over the course of 70 d implantation period, H&E and Masson's trichrome (MTS) analysis revealed that silk matrices were capable of supporting both urothelial and smooth muscle regeneration at the defect site. Prominent uroplakin and contractile protein expression (α-actin, calponin, and SM22α) was evident by immunohistochemical analysis demonstrating maturation of the reconstituted bladder wall compartments. Gel spun silk matrices also elicited a minimal acute inflammatory reaction following 70 d of bladder integration, in contrast to parallel assessments of small intestinal submucosa (SIS) and poly-glycolic acid (PGA) matrices which routinely promoted evidence of fibrosis and chronic inflammatory responses. Voided stain on paper analysis revealed that silk augmented animals displayed similar voiding patterns in comparison to non surgical controls by 42 d of implantation. In addition, cystometric evaluations of augmented bladders at 70 d post-op demonstrated that silk scaffolds supported significant increases in bladder capacity and voided volume while maintaining similar degrees of compliance relative to the control group. These results provide evidence for the utility of gel spun silk-based matrices for functional bladder tissue engineering applications.
    Biomaterials 10/2010; 32(3):808-18. · 8.31 Impact Factor
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    ABSTRACT: Overdistension of hollow organs evokes pathological changes characterized by smooth muscle remodeling. Mechanical stimuli induce smooth muscle cell (SMC) growth through acute activation of signaling cascades and by increased expression of soluble mitogens. Physical forces have also been implicated in ligand-independent activation of receptor tyrosine kinases, including the platelet-derived growth factor (PDGF) receptor, although the extent to which this occurs in intact tissue is unknown. Previously, we implicated Akt and activator protein-1 (AP-1) as mediators of growth and gene expression in SMC exposed to cyclic stretch or PDGF. Here we show that bladder wall distension leads to PDGFR activation and identify thrombomodulin (TM) as an Akt and AP-1 target in SMC. We demonstrate that TM, also induced by bladder stretch injury, is regulated at the transcriptional level by the AP-1 components c-jun and Fra1. Mutation of an AP-1 motif at -2010/-2004 abolished both AP-1 binding and PDGF responsiveness of the TM promoter. Fra1 silencing diminished PDGF-induced TM expression and SMC cell cycle transit. In contrast, TM knockdown did not affect cell growth but attenuated PDGF-stimulated SMC migration. Taken together, these results reveal new facets of TM regulation in SMC and provide the first demonstration of a role for endogenous TM in PDGF-induced cell migration. Moreover, TM induction on bladder injury suggests that it may be a biomarker for pathological smooth muscle remodeling.
    American Journal Of Pathology 07/2010; 177(1):119-31. · 4.60 Impact Factor
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    ABSTRACT: An increasing number of parents and practitioners use the Internet for health related purposes, and an increasing number of models are available on the Internet for predicting spontaneous resolution rates for children with vesicoureteral reflux. We sought to determine whether currently available Internet based calculators for vesicoureteral reflux resolution produce systematically different results. Following a systematic Internet search we identified 3 Internet based calculators of spontaneous resolution rates for children with vesicoureteral reflux, of which 2 were academic affiliated and 1 was industry affiliated. We generated a random cohort of 100 hypothetical patients with a wide range of clinical characteristics and entered the data on each patient into each calculator. We then compared the results from the calculators in terms of mean predicted resolution probability and number of cases deemed likely to resolve at various cutoff probabilities. Mean predicted resolution probabilities were 41% and 36% (range 31% to 41%) for the 2 academic affiliated calculators and 33% for the industry affiliated calculator (p = 0.02). For some patients the calculators produced markedly different probabilities of spontaneous resolution, in some instances ranging from 24% to 89% for the same patient. At thresholds greater than 5%, 10% and 25% probability of spontaneous resolution the calculators differed significantly regarding whether cases would resolve (all p <0.0001). Predicted probabilities of spontaneous resolution of vesicoureteral reflux differ significantly among Internet based calculators. For certain patients, particularly those with a lower probability of spontaneous resolution, these differences can significantly influence clinical decision making.
    The Journal of urology 02/2010; 183(4):1568-72. · 4.02 Impact Factor
  • Journal of Urology - J UROL. 01/2010; 183(4).
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    ABSTRACT: When children are initially diagnosed with vesicoureteral reflux most undergo a period of antibiotic prophylaxis followed by serial imaging. Although improvement in reflux grade through time presumably predicts eventual resolution, the significance of changing grade through time is unknown. We examined whether improvement in reflux on serial imaging predicts resolution. We retrospectively reviewed 1,761 children diagnosed with vesicoureteral reflux, of whom 965 had a minimum of 2 years of followup. We examined initial reflux grade and grade on serial imaging up to 5 years after the original diagnosis. For each child it was determined whether reflux was resolved, eventually resolved or never resolved. Groups were further stratified by clinical characteristics. Multivariate analysis revealed that male gender (HR 1.33, p = 0.05), age younger than 1 year at diagnosis (HR 1.35, p = 0.004), lower grade at presentation (grade I HR 2.2, grade II HR 1.96, grade III HR 1.33; p <0.001) and unilateral reflux (HR 1.39, p = 0.001) were all independent predictors of reflux resolution. Multivariate analysis also showed that reflux improvement on imaging 1 year after diagnosis (HR 3.14, p <0.0001) and improvement from the previous year at any point during followup (HR 1.8, p = 0.009) were independent predictors of reflux resolution. Consistent with previous findings, male gender, lower reflux grade at presentation, age less than 1 year at presentation and unilateral reflux were all predictive of reflux resolution. Our analysis also demonstrated that improvement in reflux grade on imaging study 1 year after diagnosis was predictive of resolution, and that reflux improvement from the previous year at any point during followup was an independent predictor of resolution. This information will prove valuable in clinical counseling and therapeutic decision making.
    The Journal of urology 12/2009; 183(2):709-13. · 4.02 Impact Factor
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    ABSTRACT: In women with vaginal agenesis progressive perineal dilation provides a minimally invasive method to create a functional vagina without the attendant risks or complications of traditional surgical options. We report our 12-year experience with this technique. Patients with vaginal agenesis treated at our institution were analyzed retrospectively and followed prospectively using case report forms and semistructured interviews. Patients diagnosed with vaginal agenesis were counseled on vaginal reconstruction options. Those electing progressive perineal dilation were instructed on the proper use of vaginal dilators by one of us (MRL) and advised to dilate 2 or 3 times daily for 20 minutes. All patients received physician, nursing and social work education and counseling. Parameters reviewed included primary diagnosis, start and end of vaginal dilation, dilation frequency, dilator size, sexual activity and whether the patient experienced pain or bleeding with dilation or sexual activity. Functional success was defined as the ability to achieve sexual intercourse, vaginal acceptance of the largest dilator without discomfort or a vaginal length of 7 cm. Univariate and multivariate analysis was performed to identify factors associated with successful neovaginal creation. From 1996 to 2008 we enrolled 69 females with vaginal agenesis in a progressive perineal dilation program. The primary diagnosis was Mayer-Rokitansky-Küster-Hauser syndrome in 64 patients. Mean age at the start of vaginal dilation was 17.5 years (range 14 to 35) Mean followup was 19 months (range 0 to 100). Four patients (5.7%) were lost to followup. In 7 of the remaining 65 patients (12%) treatment failed due to noncompliance and 50 (88%) achieved functional success at a median of 18.7 months. Patients who dilated frequently (once daily or greater) achieved a functional neovagina at a mean +/- SD of 4.3 +/- 2.4 months. Functional success correlated positively with frequent (once daily or greater) dilation and the initiation of sexual activity. Complications were minor. Three patients reported infrequent pain and 2 reported a single episode of bleeding with dilation. A total of 18 sexually active patients reported satisfactory intercourse without dyspareunia. Progressive perineal dilation for neovaginal creation is a valuable, minimally invasive therapy to create a functional vagina with a high success rate and a much lower complication rate than that in published surgical series. Given these findings, progressive perineal dilation should be offered as first line therapy in adolescents with a congenitally absent vagina.
    The Journal of urology 09/2009; 182(4 Suppl):1882-9. · 4.02 Impact Factor
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    ABSTRACT: We present an experimental study on four rabbits to demonstrate the feasibility of near-infrared spectroscopy in the noninvasive assessment of testicular torsion. We used a multi-distance frequency-domain method, based on a fixed detector position and a 9-mm linear scan of the illumination optical fibers, to measure absolute values of pre- and post-operative testicular oxygen saturation. Unilateral testicular torsions (by 0°, 540° or 720°) on experimental testes and contralateral sham surgeries (no torsion) on control testes were performed and studied. Our results showed (a) a consistent baseline absolute tissue oxygen saturation value of 78% +/- 5%; (b) a comparable absolute saturation of 77% +/- 6% on the control side (testes after sham surgery); and (c) a significantly lower tissue oxygen saturation of 36% +/- 2% on the experimental side (testes after 540° or 720° torsion surgery). These results demonstrate the capability of frequency domain nearinfrared spectroscopy in the assessment of absolute testicular hemoglobin desaturation caused by torsion, and show promise as a potential method to serve as a complement to conventional color and spectral Doppler ultrasonography.
    Proc SPIE 01/2009;
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    ABSTRACT: We present a quantitative near-IR spectroscopy study of the absolute values of oxygen saturation of hemoglobin before and after surgically induced testicular torsion in adult rabbits. Unilateral testicular torsions (0, 540, or 720 deg) on experimental testes and contralateral sham surgery on control testes are performed in four adult rabbits. A specially designed optical probe for measurements at multiple source-detector distances and a commercial frequency-domain tissue spectrometer are used to measure absolute values of testicular hemoglobin saturation. Our results show: (1) a consistent baseline absolute tissue hemoglobin saturation value of 78+/-5%, (2) a comparable tissue hemoglobin saturation of 77+/-6% after sham surgery, and (3) a significantly lower tissue hemoglobin saturation of 36+/-2% after 540- and 720-deg testicular torsion surgery. Our findings demonstrate the feasibility of performing frequency-domain, multidistance near-IR spectroscopy for absolute testicular oximetry in the assessment of testicular torsion. We conclude that near-IR spectroscopy has potential to serve as a clinical diagnostic and monitoring tool for the assessment of absolute testicular hemoglobin desaturation caused by torsion, with the possibility of serving as a complement to conventional color and spectral Doppler ultrasonography.
    Journal of Biomedical Optics 01/2009; 14(5):054027. · 2.88 Impact Factor

Publication Stats

255 Citations
102.30 Total Impact Points

Institutions

  • 2007–2014
    • Childrens Hospital of Pittsburgh
      • Division of Pediatric Nephrology
      Pittsburgh, Pennsylvania, United States
    • Boston Children's Hospital
      • Department of Urology
      Boston, MA, United States
  • 2004–2012
    • University of Pittsburgh
      • Department of Urology
      Pittsburgh, PA, United States
  • 2011
    • Children's Medical Center Dallas
      Dallas, Texas, United States
  • 2009
    • Harvard Medical School
      Boston, Massachusetts, United States