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Dive into the research topics where Michael A. Keating is active.

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Featured researches published by Michael A. Keating.


The Journal of Urology | 1989

Cryptorchidism, Orchiopexy and Infertility: A Critical Long-Term Retrospective Analysis

Marc Cendron; Michael A. Keating; Dale S. Huff; C.E. Koop; Howard M. Snyder; John W. Duckett

We assessed the fertility of 40 patients who underwent orchiopexy between 1950 and 1960. Testicular biopsies also had been performed at operation, a practice exceptional for the era. Of 23 patients with unilateral undescended testes who attempted to have children 20 (87 per cent) were successful. In contrast, only 3 (33 per cent) of 9 patients with bilateral undescended testes fathered children. Over-all sperm counts in 16 patients were low but they were not predictive of paternity. Testicular biopsy specimens were reviewed and the fertility index was determined. In most cases a good correlation was found between histological status and paternity status.


The Journal of Urology | 1993

Anatomical, morphological and volumetric analysis: a review of 759 cases of testicular maldescent.

Marc Cendron; Dale S. Huff; Michael A. Keating; Howard M. Snyder; John W. Duckett

Undescended testis is the most frequent disorder of male sexual differentiation affecting 0.8% of all boys by age 1 year. Anatomical and descriptive features of undescended testis lack standardization, and often do not reflect intraoperative findings. We review a large cohort of patients treated for undescended testis and analyze anatomical, morphological and volumetric findings at orchiopexy. Of 759 patients 1 month to 9 years old entered into the study between 1985 and 1990 at our hospital 55% underwent surgery between ages 8 months and 4 years, 15.5% had bilateral undescended testis and 27.6% had a nonpalpable gonad. Preoperative physical findings correlated poorly with intraoperative observation with respect to testicular position. An ectopic gonad was diagnosed in 15% of the patients, most of whom had a patent processus vaginalis. Gubernacular attachment was in the scrotum in only a third of all cases studied. Undescended testes were softer and smaller than the contralateral gonad in the majority of cases. To our knowledge ours is the first study to correlate preoperative and intraoperative findings in cases of undescended testis. New anatomical as well as morphological and volumetric data are provided.


The Journal of Urology | 1989

Changing concepts in management of primary obstructive megaureter

Michael A. Keating; Jose Escala; Howard M. Snyder; Sydney Heyman; John W. Duckett

The management of neonatal urinary tract dilatations represents one of the most challenging dilemmas in pediatric urology today. We have been confronted with 44 renal units in 35 neonates diagnosed as having primary obstructive megaureter during the last 6 years. Of these units 23 in 17 infants were diagnosed antenatally and 20 (87 per cent) have been managed without surgical intervention. Notably, 16 renal units were graded as moderate to severe megaureters by an excretory urogram. The decision to manage conservatively was based on the initial extraction of the 99mdiethylenetriaminepentaacetic acid renal scan (the extraction factor). This estimate of absolute renal function has been used to differentiate dilatations with obstructive implications for the renal parenchyma from those without. Significantly, expectant treatment has resulted in improvement of dilatation on sequential excretory urograms in 15 megaureters and none has shown a deterioration of function by renal scan. Similar diagnostic criterion also has resulted in conservative management for 12 of 21 additional neonatal megaureters seen during this period with symptoms or they were discovered serendipitously. Only 2 of these 12 megaureters required surgical correction. The neonatal primary megaureter appears in many cases to represent a different entity than those that commonly presented before the advent of antenatal and perinatal diagnosis.


The Journal of Urology | 1990

Preservation of the Urethral Plate in Hypospadias Repair: Extended Applications and Further Experience with the Onlay Island Flap Urethroplasty

J.G. Hollowell; Michael A. Keating; Howard M. Snyder; John W. Duckett

The onlay island flap urethroplasty, a variant of the transverse preputial (tubularized) island flap, was originally described for repair of anterior hypospadias. However, many cases of mid and proximal hypospadias have a well developed urethral plate and exhibit little or no chordee after release of skin tethering. Patients with this combination of findings are ideal candidates for onlay island flap urethroplasty regardless of initial meatal position. During the last 5 years the onlay island flap has been used for repair of mid to posterior hypospadias in 31 patients (38% of the cases). These are variants that formerly would have required more extensive urethroplasty. Because of the technical advantages of the onlay island flap this alteration in technique selection has resulted in fewer complications. When applied to mid and posterior hypospadias the onlay island flap maintained a significantly lower complication rate (10%) compared to other standard techniques. Preservation of the urethral plate in hypospadias repair is a principle with significant implications to an extended variety of hypospadias.


The Journal of Urology | 1989

Hinging the Urethral Plate in Hypospadias Meatoplasty

Mark A. Rich; Michael A. Keating; Howard M. Snyder; John W. Duckett

A technique is described for creation of a cosmetically normal, vertical slit-like urethral meatus in conjunction with common hypospadias reconstructions that preserve the urethral plate. The distal portion of the urethral plate is incised longitudinally in the midline. This incision allows the flat and rigid urethral plate to be folded or hinged during glans plasty, molding it into an anatomically correct vertical slit configuration. This modification has been applied successfully to a variety of meatal-based flap and onlay island flap urethroplasties with no increased morbidity and a significant improvement in meatal cosmetic results.


The Journal of Urology | 1992

Managing Apparent Ureteropelvic Junction Obstruction in the Newborn

Patrick C. Cartwright; John W. Duckett; Michael A. Keating; Howard M. Snyder; Jose Escala; Bruce Blyth; Sydney Heyman

A total of 97 newborns with apparent ureteropelvic junction obstruction was evaluated from mid 1984 to 1989. Evaluation and management are described. Of these patients 39 with an affected kidney showing good initial differential function (greater than 35%) by diethylenetriaminepentaacetic acid scan and 2 showing diminished function (less than 35%) were followed nonoperatively. Six patients (15%) eventually required pyeloplasty for diminishing function (4), urinary tract infections (1) or symptoms of colic (1). The 4 patients with diminishing function improved after pyeloplasty to at least the initial level. A total of 12 patients with good initial function (greater than 35%) of the affected kidney underwent early pyeloplasty (within 6 weeks of diagnosis). They were compared to the similar group of patients managed nonoperatively and followed by sequential renal scans. Eventual changes in percentage differential function in the nonoperative and early surgery groups were +2.8% and +4.1%, respectively. Changes in extraction factor were +0.8% (nonoperative group) and +0.9% (surgery group). No statistically significant difference was found. In the kidney with apparent ureteropelvic junction obstruction and good function, an initial nonoperative approach with sequential renal scan followup and pyeloplasty as needed appears to be reasonable and has resulted in no permanent loss of function.


Urologic Clinics of North America | 2000

Leydig cell tumors and tumors associated with congenital adrenal hyperplasia.

Mark A. Rich; Michael A. Keating

Testicular cancers occur at a rate of 2 cases per 100,000 males. Gonadal stromal tumors, including Leydig cell tumors and tumors of the adrenogenital syndrome, account for 1% to 3% of these neoplasms. Despite their rarity, these hormone-producing tumors are particularly interesting because of their potential for causing endocrinologic manifestations in prepubertal and adult males. They are also clinically significant, and early identification is critical to avoid profound and often irreversible developmental changes in affected children. An accurate diagnosis is important to differentiate tumors that will respond to medical management from tumors that require definitive surgical therapy.


The Journal of Urology | 1989

Technical Challenge of the Megameatus Intact Prepuce Hypospadias Variant: The Pyramid Procedure

John W. Duckett; Michael A. Keating

An unusual variant of hypospadias is the focus of this report. This distal variant consists of a megameatus and urethra in the presence of intact foreskin. Recognition is important, not only because of the uncommon combination of findings, which run contrary to the classical presentation of most hypospadias, but also because of the technical shortcomings that are encountered during repair with standard techniques. The pyramid procedure is described, which allows for an end-on dissection of the distal megameatus-urethra, enabling a reduction in caliber of both while facilitating remodeling of the glans. The procedure has proved to be successful and reliable for this particular hypospadias variant. No complications have been encountered.


The Journal of Urology | 1990

Low Transurethral Incision of Single System Intravesical Ureteroceles in Children

Mark A. Rich; Michael A. Keating; Howard M. Snyder; John W. Duckett

Single system intravesical ureteroceles in children usually result in various degrees of hydroureteronephrosis requiring surgical intervention to provide drainage, decompression and preservation of renal function. Our experience with 7 symptomatic single system ureteroceles in 5 children managed by low transverse endoscopic ureterocele incision is reviewed. After endoscopic incision, hydroureteronephrosis decreased in all patients. Vesicoureteral reflux after incision was noted in only 1 kidney. The technique of short (2 to 3 mm.) low transverse ureterocele incision is recommended for the initial management of single system ureteroceles to relieve obstruction. Preservation of the flap valve ureteral antireflux mechanism is possible in most children. The technique is simply performed, can be safely done in the youngest child and, in many, obviates the need for a further operation.


The Journal of Urology | 1993

A Surgical Approach to Reoperative Orchiopexy

Patrick C. Cartwright; Satish Velagapudi; Howard M. Snyder; Michael A. Keating

While techniques for initial orchiopexy are well known, descriptions of a surgical approach to the more difficult reoperative case are scarce. We describe 25 patients undergoing reoperative orchiopexy following prior herniorrhaphy, hydrocelectomy or attempted orchiopexy. A technique of en bloc spermatic cord mobilization from an inferior approach is detailed. This approach is designed to minimize the potential for spermatic cord injury during reoperation, and has proved to be safe and reliable.

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John W. Duckett

Children's Hospital of Philadelphia

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Howard M. Snyder

Children's Hospital of Philadelphia

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Jose Escala

Children's Hospital of Philadelphia

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Mark A. Rich

Children's Hospital of Philadelphia

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Dale S. Huff

Children's Hospital of Philadelphia

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Marc Cendron

Boston Children's Hospital

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Sydney Heyman

Children's Hospital of Philadelphia

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Agnes Pierce

Children's Hospital of Philadelphia

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Bruce Blyth

Children's Hospital of Philadelphia

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