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Dive into the research topics where Paul A. Merguerian is active.

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Featured researches published by Paul A. Merguerian.


The Journal of Urology | 2000

THE DYSFUNCTIONAL VOIDING SCORING SYSTEM: QUANTITATIVE STANDARDIZATION OF DYSFUNCTIONAL VOIDING SYMPTOMS IN CHILDREN

Walid A. Farhat; Darius J. Bägli; Gianpaolo Capolicchio; Sheila O’Reilly; Paul A. Merguerian; Antoine E. Khoury; Gordon A. McLorie

PURPOSE Academic research on pediatric nonneurogenic voiding dysfunction has long been hampered by the lack of a standardized reporting system for voiding symptoms. We evaluated the performance of a newly devised, objective instrument to quantify or grade the severity of abnormal voiding behaviors of children. MATERIALS AND METHODS There were 10 voiding dysfunction parameters that were assigned scores of 0 to 3 according to prevalence, and possible total scores ranged from 0 to 30. The Dysfunctional Voiding Symptom Score was completed by 2 groups of patients. Group 1 consisted of patients 3 to 10 years old presenting to the pediatric urology clinic with a history of diurnal urinary incontinence, urinary tract infections or abnormal voiding habits. Group 2 consisted of an age matched cohort with no history of urological complaints presenting to hospital clinics outside of urology. Patients diagnosed with organic or anatomical disease, such as posterior urethral valves or meningomyelocele, were excluded from our analysis. RESULTS Group 1 consisted of 104 patients (female-to-male ratio 4:1) with a median symptom score of 14 and group 2 consisted of 54 patients (female-to-male ratio 1.3:1) with a median score of 4. The dysfunctional voiding odds ratio was 2.93 for females compared to that of males. Using receiver operating characteristics the optimum cutoff score was 6.026 (sensitivity 92.77% and specificity 87.09%) for females and 9.02 (sensitivity of 80.95% and specificity of 91. 30%) for males. In addition, we found certain questions to be more reflective than others of dysfunctional voiding symptoms in our population. CONCLUSIONS The Dysfunctional Voiding Symptom Score appears to provide accurate and objective, that is, numerical, grading of voiding behaviors of children. Comparative research studies of dysfunctional voiding diagnosis and response to therapy as well as objective measurements of treatment efficacy and outcomes analysis should be aided greatly by this system.


The Journal of Urology | 2000

REGENERATION OF FUNCTIONAL BLADDER SUBSTITUTES USING LARGE SEGMENT ACELLULAR MATRIX ALLOGRAFTS IN A PORCINE MODEL

Pramod P. Reddy; Diego J. Barrieras; Gregory J. Wilson; Darius J. Bägli; Gordon A. McLorie; Antoine E. Khoury; Paul A. Merguerian

PURPOSE We previously reported on the short-term (4 weeks) morphometric analysis of a large bladder acellular matrix allograft used as a bladder bioprosthesis (average size 24 cm.2). We demonstrated cellular repopulation through the entire thickness of the graft. We now present the long-term (12 weeks) morphometric results of graft regenerated porcine bladders using segments measuring an average of 40 cm.2. MATERIALS AND METHODS Bladders harvested from pigs were subjected to detergent and enzymatic extractions to render them acellular. Partial cystectomy was performed in 21 pigs and the defect was repaired with a bladder acellular matrix allograft (average size 40.52 cm.2). Of the animals 8 were sacrificed at 1, 2 and 4 weeks and 13 were sacrificed at 8 and 12 weeks. To evaluate cellular repopulation and matrix reorganization the native bladder and graft were analyzed using standard histological and immunofluorescent techniques. To evaluate for calcium deposits in the grafts a radiological evaluation of the graft was performed after explantation. RESULTS All animals survived the surgical procedure and there were no significant urinary leaks. No stones were noted in any of the bladders. At 1 week there was a diffuse infiltration with acute inflammatory cells. At 2 weeks the luminal surface of the graft was lined with a single layer of urothelium, and there was stromal infiltration with unorganized smooth muscle cells and angiogenesis. At 4 weeks the urothelium was multilayered with organizing groups of smooth muscle cells and angiogenesis. At 8 and 12 weeks there was repopulation throughout the bladder acellular matrix allograft implant with all native cellular components participating. CONCLUSIONS We present evidence that large patch bladder acellular matrix allograft implantation is technically feasible and may prove to be a viable surgical alternative to bladder augmentation with intestinal segments. Its advantages may include the potential for complete and functional regeneration of a bladder substitute.


BJUI | 2001

Acellular bladder matrix allografts in the regeneration of functional bladders : evaluation of large-segment (> 24 cm2) substitution in a porcine model

Paul A. Merguerian; Pramod P. Reddy; Diego J. Barrieras; Gregory J. Wilson; K. Woodhouse; Darius J. Bägli; Gordon A. McLorie; Antoine E. Khoury

Objectives To evaluate the use of a large‐segment (> 24 cm2) bladder substitution with porcine bladder acellular matrix allograft (BAMA) in a large animal model.


The Journal of Urology | 1990

Lithostar Extracorporeal Shock Wave Lithotripsy in Children

Emmanuel O. Abara; Paul A. Merguerian; Gordon A. McLorie; Kostantinos E. Psihramis; Michael A.S. Jewett; Bernard M. Churchill

The Siemens Lithostar lithotriptor was used to treat 20 children (4 to 17 years old) with renal or ureteral calculi. Two patients had bilateral renal and 2 had ureteral calculi. Of 34 calculi treated 47% were in the renal pelvis, 29% in the lower calix, 12% in the upper calix, 3% in the middle calix and 9% in the upper ureter. Stone size ranged from 2 X 2 to 40 X 20 mm. and averaged 10 X 7 mm. Of the children 60% were treated while they were under neuroleptic anesthesia. No major complications were encountered. The 3-month rate free of stones after 1 treatment was 60% and increased to 80% with multiple treatments. The success rate, defined as being either free of stones or with residual fragments equal to or less than 4 mm. in diameter, was 95%. We conclude that lithotripsy with the Lithostar device in children, at least for the short term, is safe and effective.


The Journal of Urology | 2001

A population based analysis of continence outcomes and bladder exstrophy.

Gianpaolo Capolicchio; Gordon A. McLorie; Walid A. Farhat; Paul A. Merguerian; Darius J. Bägli; Antoine E. Khoury

PURPOSE Whereas the literature on bladder exstrophy is replete with outcomes of specific continence surgical procedures in highly select patients, there are no data on the outcomes related to continence for a complete exstrophy population, which is more comprehensive with respect to a variety of surgical procedures performed to achieve continence. To provide urologists and patients with an overview of potential continence outcomes devoid of any selection bias, we report on a comprehensive exstrophy population, focusing on the various procedures required for urinary continence. MATERIALS AND METHODS We reviewed the charts of all patients with bladder and cloacal exstrophy who underwent a staged repair to achieve urinary continence at a single institution between 1988 and 1998. Urinary continence was then correlated to the types of surgical procedures, and subgroup analysis for predictors of urinary continence was performed. The type of bladder neck reconstruction allowed subgrouping cases into group 1-bladder neck reconstruction only, group 2-bladder neck reconstruction with augmentation and/or appendicovesicostomy and group 3-bladder neck closure. RESULTS Of the 43 patients identified 26 were male, 4 had cloacal exstrophy and 3 had complex exstrophy variants with ectopic hindgut and spina bifida. Groups 1 to 3 comprised 9, 15 and 19 patients with urinary continence rates of 56%, 67% and 100%, respectively. The age at which patients became continent was delayed in groups 2 and 3 (8.2 and 8.7 years, respectively) compared to group 1 (4.8). Of all the potential variants measured gender was the strongest predictor of continence with 94% of females versus 69% of males achieving it. Of the males those with (57%) compared to those without (83%) a history of bladder neck stenosis or paraexstrophy flaps had worse continence. Repeat bladder neck reconstruction was only successful in 23% of patients. CONCLUSIONS All patients can be rendered continent but many may achieve this successful outcome by other procedures following initial bladder neck reconstruction. When managing failed bladder neck reconstruction, the type of surgical repair chosen may need to address the need for enhanced bladder storage and the issue of potential bladder augmentation. The advances made in the treatment of the epispadiac urethra may now facilitate clean intermittent catheterization. Earlier recognition of the need for adjunctive storage procedures in addition to bladder neck reconstruction may facilitate the timing of providing enhanced continence, independence and self-esteem, and do so with fewer operative procedures. We speculate that the current complete urethral and bladder repair in newborns will add further to the storage functions of the native bladder tissues and improve the potential of achieving more effective bladder outlet control.


Urology | 2000

Outcomes of primary valve ablation versus urinary tract diversion in patients with posterior urethral valves.

Walid A. Farhat; Gordon A. McLorie; Gianpaolo Capolicchio; Antoine E. Khoury; Darius J. Bägli; Paul A. Merguerian

OBJECTIVES Although valve ablation is the treatment of choice for patients with posterior urethral valves, debate continues as to the role of urinary diversion. We sought to retrospectively compare the clinical and radiologic outcomes between valve ablation and urinary diversion for patients with posterior urethral valves. METHODS We retrospectively reviewed the records of 50 consecutive patients with posterior urethral valves since January 1995. On the basis of the initial renal function and radiologic findings, patients were divided into three groups: group 1, normal renal function and radiologically normal upper tracts; group 2, normal renal function with hydronephrosis and/or reflux; and group 3, azotemia with hydronephrosis or reflux. RESULTS All 22 patients in group 1 were treated with valve ablation. After a mean follow-up of 32 months, these children had normal renal function and no evidence of upper tract deterioration. All 13 patients in group 2 were also treated with valve ablation. The radiologic abnormalities (hydronephrosis, reflux) resolved in 50% of cases, with an average follow-up of 28 months. Of the 15 patients in group 3, 7 underwent valve ablation and 8 underwent urinary diversion. Urinary diversion was performed in patients with renal deterioration and severe hydronephrosis and/or high-grade reflux. Renal function returned to normal in all patients who underwent valve ablation except one; renal function returned to normal in only 3 of 8 patients who underwent urinary diversion. Radiologically, the severity of the hydronephrosis and reflux was downgraded in patients who underwent valve ablation but not in the diverted group. CONCLUSIONS Valve ablation is the mainstay of treatment for patients with posterior urethral valves. Prenatal and postnatal factors, such as renal dysplasia and urinary tract infection, respectively, rather than the posterior valve treatment dictate the long-term renal and radiologic outcomes.


The Journal of Urology | 2000

Lessons learned from laser tissue soldering and fibrin glue pyeloplasty in an in vivo porcine model.

Diego J. Barrieras; Pramod P. Reddy; Gordon A. McLorie; Darius J. Bägli; Antoine E. Khoury; Walid A. Farhat; Lothar Lilge; Paul A. Merguerian

PURPOSE We compared sutured pyeloplasty to 2 newer techniques of tissue anastomosis, including laser soldered pyeloplasty using a diode laser with 50% albumin solder mixed with indocyanine green and fibrin glue. MATERIALS AND METHODS We performed 53 pyeloplasties in 50 pigs using suture, laser or fibrin glue. In the immediate group anastomotic leak pressure was measured immediately postoperatively, and then animals were euthanized. At 1, 3 and 4 weeks postoperatively a pressure flow study at 10 cc per minute in cm. H2O was performed, and tissue was sent for histological and collagen content analysis. RESULTS In the immediate studies laser soldering achieved a significantly higher mean anastomotic leak pressure (50.5 +/- 15.1 cm. H2O) than sutured (17.3 +/- 5.4) or fibrin glued (3.5 +/- 1.5) repairs. In the 1, 2 and 4-week studies animals in the sutured pyeloplasty group had no complications, and all pressure flow studies except 1 were normal. However, in the laser soldered groups we observed 8 urinomas in 19 animals, and most occurred during the first part of our study. This complication was prevented by stopping urine flow at the anastomotic site at laser irradiation and by improving application of the solder. Of the 11 animals in which pressure flow studies were performed only 2 were obstructed. Of the 7 chronic fibrin glue group 4 animals had urinomas and 2 had unobstructed pressure flow studies. Histological studies and immunohistochemical staining for collagen showed no differences in collagen distribution among the 3 procedures. CONCLUSIONS Laser soldering and fibrin glue pyeloplasties are not superior in the long-term compared to sutured pyeloplasty. Fibrin glue in our animal model had the highest failure rate. Further improvements in the technical aspect of laser tissue welding need to be made to benefit from its theoretical advantages in minimally invasive surgery.


The Journal of Urology | 1999

Concomitant modified bladder neck closure and Mitrofanoff urinary diversion.

Antoine E. Khoury; Sanjiv Agarwal; Darius J. Bägli; Paul A. Merguerian; Gordon A. McLorie

PURPOSE We describe a modification of bladder neck closure for managing urinary incontinence in children. MATERIALS AND METHODS In 11 patients with intractable urinary incontinence that persisted after multiple failed surgical procedures we performed modified bladder neck closure with construction of a catheterizable continent conduit. RESULTS Mean followup is 3 years. All patients were continent after the procedure and none had a fistula or urinary leakage. One patient required stomal and conduit revision, and bladder stones in 3 necessitated endoscopic removal. CONCLUSIONS We recommend this modified technique of bladder neck closure as an option for managing urinary incontinence in a complex group of children because it allows the achievement of continence with minimal morbidity.


The Journal of Urology | 2001

A prospective randomized clinical trial to evaluate methods of postoperative care of hypospadias

Gordon A. McLorie; Byron Joyner; Daniel B. Herz; Jackie McCALLUM; Darius J. Bägli; Paul A. Merguerian; Antoine E. Khoury

PURPOSE Hypospadias repair is a common operation performed by pediatric urologists. Perhaps the greatest variable and source of controversy of postoperative care is the surgical dressing. We hypothesized that using no dressing would achieve surgically comparable results to those traditionally achieved by a postoperative dressing and it would also simplify postoperative parent delivered home care. Accordingly we designed a prospective randomized clinical trial to compare surgical outcome and postoperative care after hypospadias repair in boys with no dressing and those who received 1 of the 2 most common types of dressing. MATERIALS AND METHODS In a 12-month period 120 boys with an average age of 2.2 years underwent primary 1-stage hypospadias repair at a single center with 4 participating surgeons. Repair was performed in 60 boys with proximal and 60 with distal hypospadias on an outpatient basis. Ethics and Internal Review Board approval, and informed consent were obtained. Boys were then prospectively randomized to receive no dressing, an adhesive biomembrane dressing or a compressive wrap dressing. Comprehensive instructions on postoperative care were distributed to all families and a questionnaire was distributed to the parents at the initial followup. Surgical outcome was evaluated and questionnaire responses were analyzed. Fishers exact test was done to test the significance of differences in surgical outcomes and questionnaire responses. RESULTS A total of 117 boys completed the prospective randomized trial. Surgical staff withdrew 3 cases from randomized selection to place a dressing for postoperative hemostasis. We obtained 101 questionnaires for response analysis. The type or absence of the dressing did not correlate with the need for repeat procedures, urethrocutaneous fistula, or meatal stenosis or regression. Analysis revealed less narcotic use in the no dressing group and fewer telephone calls to the urology nurse, or on-call resident and/or fellow. These findings were statistically significant. In addition, there were more unscheduled visits to the urology clinic, emergency room or primary physician office by boys with than without a dressing. Furthermore, 29% of the parents were not psychologically prepared to remove the dressing and 12% were so reluctant that the dressing was removed at the urology outpatient clinic. CONCLUSIONS The surgical outcome and rate of adverse events or complications were not compromised without a postoperative dressing. An absent dressing simplified postoperative ambulatory parent delivered home care. We recommend that dressings should be omitted from routine use after hypospadias repair.


The Journal of Urology | 1998

OUTCOME ANALYSIS OF RHABDOMYOSARCOMA OF THE LOWER URINARY TRACT

Paul A. Merguerian; Sanjiv Agarwal; Mark T. Greenberg; Darius J. Bägli; Antoine E. Khoury; Gordon A. McLorie

PURPOSE Multimodal therapy has resulted in a high cure rate for genitourinary rhabdomyosarcoma. We propose that the strategy of induction chemotherapy followed by excision and reconstruction without radiotherapy may provide a high cure rate without the late sequelae of pelvic radiotherapy. MATERIALS AND METHODS We reviewed the records of 13 patients with a mean age of 3.3 years diagnosed with rhabdomyosarcoma of the urinary tract from 1986 to 1996. The primary site was the bladder in 4 cases and prostate in 9. After biopsy confirmation of the diagnosis patients were treated with chemotherapy and subsequent surgery, while radiotherapy was reserved for those with residual disease. RESULTS After induction chemotherapy 8 patients underwent tumor excision via an organ sparing approach, which involved radical prostatectomy and partial cystectomy with or without bladder augmentation. In 5 patients the final pathological analysis showed positive margins. Repeat surgery in 6 patients included complete cystectomy and urinary diversion in 2 who had positive margins and recurrence after radiotherapy, urethrectomy and continent diversion for positive margins in 1, partial cystectomy and continent diversion in 1, and radical prostatectomy, partial cystectomy and continent diversion in 1 with stage IV disease who had local recurrence. In the latter case ileocystoplasty had been performed for a small noncompliant bladder. Six patients with microscopic residual or metastatic disease received radiotherapy. At a mean followup of 5.6 years 11 patients are disease-free. Continence was preserved in all reconstructed cases. Erections were reported in 8 patients, and renal function was maintained in 10. CONCLUSIONS Our results suggest that urinary tract reconstruction may be safely performed at primary excision surgery, radiotherapy induced morbidity may be minimized by limiting radiotherapy to residual and metastatic disease, frozen section results may be false-negative, potency may be achieved and radiological disappearance of the tumor should be confirmed histologically.

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Lothar Lilge

Princess Margaret Cancer Centre

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