Mahmoud A. Bazeed

Prediction of success rate after extracorporeal shock-wave lithotripsy of renal stones--a multivariate analysis model.

Objectives: To define prognostic factors that affect the success rate after extracorporeal shock‐wave lithotripsy (ESWL) of renal calculi and to estimate the probability of stone‐free status using a regression analysis model. Material and Methods: Between February 1992 and February 2002, 2954 patients with single or multiple radiopaque renal stones (<30 mm) underwent ESWL monotherapy. The results of treatment were evaluated after 3 months of follow‐up. Treatment success was defined as complete clearance of the stones with no residual fragments. The stone‐free rate was correlated with stone features and patient characteristics using the χ 2 test. Factors found to be significant using the χ 2 test were further analyzed using multivariate regression analysis. Results: At 3‐month follow‐up, the overall stone‐free rate using ESWL monotherapy was 86.7%. Failure to disintegrate the stones was observed in 7.3% of cases (n = 216) and failure to clear the fragmented stones occurred in 6% (n = 177). Repeat ESWL was needed in 53% of cases. Static steinstrasse occurred in 4.9% of cases (n = 146) and post‐ESWL auxiliary procedures were required in 4% (n = 118). Using the χ 2 test, patient age (p < 0.001), stone size (p < 0.001), location (p < 0.001), number (p < 0.001) and nature (p = 0.003), radiological renal picture (p < 0.001) and congenital renal anomalies (p < 0.001) had a significant impact on the stone‐free rate. Multivariate analysis excluded stone nature from the logistic regression model while other factors maintained their statistically significant effect on success rate, indicating that they were independent predictors. A regression analysis model was designed to estimate the probability of stone‐free status after ESWL. The sensitivity of the model was 83%, the specificity 91% and the overall accuracy 87%. Conclusion: Patient age, stone size, location and number, radiological renal features and congenital renal anomalies are prognostic factors determining stone clearance after ESWL of renal calculi. Our regression model can predict the probability of the success of ESWL with an accuracy of 87%.

Conservative surgery of renal cell carcinoma.

From 1967 to 1985 conservative surgery (enucleation, n = 49; partial resection, n = 7) was performed for renal tumors in 57 patients (age 31-77, mean 54.8 years). Imperative indications for conservative surgery (n = 29) were chronic renal failure, benign pathology of contralateral kidney, functional or anatomical solitary kidney, and bilateral tumors. Elective conservative surgery (n = 28) was done for small, peripherally located lesions, in cases of uncertain malignancy and in one tumor detected by chance during stone surgery. Tumors removed for imperative indications were 2-11 cm (mean 5.8 cm) in size. In the elective group, tumor size ranged from 1 to 7 cm (mean 3.3 cm). Follow-up was 6-103 months (mean 35.8 months). In the group with imperative indications, there was 1 postoperative mortality; 18 of 29 patients are alive without evidence of disease, 2 with metastases, and 2 were reoperated conservatively for local recurrences; 1 was lost to follow-up, 2 died of metastases, and 3 died due to unrelated reasons. In the elective group all 28 patients are living free of cancer.

Mechanisms of urinary continence: an animal model to study urethral responses to stress conditions.

Under conditions of stress, the urethral sphincteric mechanism has to compensate a passive bladder pressure rise induced by increase in intraabdominal pressure. To evaluate the various closure mechanisms contributing to urethral response to stress, we subjected a female dog model to the physiologic stress condition triggered by sneezing. Vesical, rectal and 4 urethral pressures during sneezing were recorded simultaneously under various experimental situations: in the intact animal, after transection of the bladder and urethra, and with the abdomen open. The effects of the Credé maneuver and of manual squeezing of the surgically exposed bladder were also recorded. The data obtained support the existence of a 2-component urethral closure mechanism under stress: the proximal closure mechanism of the smooth muscular, intrapelvic urethra is from passive transmission of abdominal pressure. It is apt to balance a passive increase in bladder pressure and thus maintain proximal closure pressure during stress. The distal closure pressure mechanism reflects active reflex contraction of the intrinsic external sphincter and pelvic floor muscles, which is capable of exceeding passive increase in bladder pressure and thus augments closure pressure during stress.

New treatment for urethral strictures

A new operative technique using synthetic, absorbable mesh for grafting a urethral defect was applied in 7 mongrel male dogs. The ventral half of the urethral circumference with its surrounding corpus spongiosum was excised for a length of 3 to 4 cm. A Dexon mesh of the same dimensions, woven in our laboratory from polyglycolic acid fibers, was sutured to the defective area. A perineal urethrotomy was established, and no splints were left behind. Dogs were studied between two and six months. Retrograde urethrography showed that the operative area healed without strictures or irregularities. Intravenous urography showed no back pressure effects, and cultured urine was always sterile. Histologic examination two months after surgery showed that the urothelium was completely healed, without inflammatory changes or disruption. Suburothelial tissues were replaced by dense collagenous connective tissue. The excised corpus spongiosum did not regenerate. After six months, the area of dense collagen described was diminished in size so that the operative area could be hardly identified except by the absence of corpus spongiosum.

Comprehensive analysis of tubularized incised-plate urethroplasty in primary and re-operative hypospadias.

To retrospectively review our experience of the tubularized incised‐plate (TIP) urethroplasty over the last 4 years.

Effect of chronic electrostimulation of the sacral roots on the striated urethral sphincter.

Chronic electrostimulation of the sacral roots induces an increase in urethral resistance due to activation of muscles of the striated urethral sphincter. Histochemical study of the urethral striated musculature (nonstimulated) revealed 3 main varieties of fibers: 1) Slow twitch fibers (35 per cent of the whole muscle); 2) Fast twitch fatiguable fibers (52 per cent); and 3) An intermediate type, fast twitch fatigue resistant (13 per cent). Ten dogs with chronically implanted electrodes at the 2nd sacral root were subjected to a program of prolonged stimulation under anesthesia. After prolonged electrostimulation, we detected hypertrophy of the striated muscle fibers of the urethra, anal sphincter and stimulated side of the tail. The stimulated muscle fibers showed a higher overall oxidative activity than the controls. This occurred both in intact and spinalized animals. We thus expect the urethral striated musculature to be more resistant to fatigue because of the increased oxidative activity. Stimulated fibers also had increased glycolytic activity as shown by the enhanced intermyofibrillar deposition, especially in the fast twitch fibers. The increased glycolytic activity may also increase fatigue resistance by producing energy during periods of low oxygen supply at the peak of muscular contraction. As a consequence of increase in oxidative and glycolytic capacities and muscular hypertrophy, we expect that the striated musculature of the urethra will be not only more resistant to fatigue but also capable of generating higher tension. Both are important in achieving continence via electrostimulation of sacral nerve roots. Approximately 3 months after conclusion of the stimulation program these changes had gradually reverted to the normal prestimulation level.

Regional Topography of Spinal Cord Neurons Innervating Pelvic Floor Muscles and Bladder Neck in the Dog: a Study by Combined Horseradish Peroxidase Histochemistry and Autoradiography

To identify the spinal origin of the innervation of the bladder neck and pelvic floor muscles retrograde axonal transport of horseradish peroxidase and tritiated horseradish peroxidase was used in a technique combining histochemistry and autoradiography. This technique proved to be suitable for differential labeling of spinal cord neurons innervating two different targets, thus extension as well as overlap of different nuclei could be judged. The parasympathetic outflow was concentrated in the intermediolateral and intermediomedial gray matter of S2, the somatic innervation was derived mostly from Onufs motor nucleus in S1 and S2. Onufs nucleus proved to be the main somatic motonucleus for pelvic floor muscles; there was no evidence of an autonomic share. The innervation of the striated urethral sphincter also originated in this nucleus; there was no basic difference when it was compared to the innervation of other pelvic floor muscles.

Functional Pattern of Sacral Root Stimulation in Dogs I. Micturition

Prior to this study, electrostimulation of the ventral sacral roots had only limited success in evacuation of the bladder because dyssynergic sphincter contraction simultaneously increased urethral resistance. Thus, pudendal nerve blockade, pudendal neurotomy, selective peripheral neurotomy, or external sphincterotomy for reduction of sphincteric resistance seemed inevitable. To avoid those procedures we used electrical sphincter fatigue to induce effective micturition with stimulation of the ventral sacral roots. Stimuli of 200 Hz frequency rapidly fatigue the dyssynergic sphincteric response but not the desired detrusor contraction, eliminating the need of interference with the sphincteric activity.

Ileal Replacement of the Bilharzial Ureter: Is it Worthwhile?

Our 14-year experience with the use of isolated ileal segments for replacement of the bilharzial ureter is analyzed retrospectively. Of 52 patients subjected to this procedure followup data were available for 38, in whom 52 ureters were repaired. The results generally were unsatisfactory: the morbidity and mortality rates were high and the percentage of functional improvement was low. The risk was higher for patients with low creatinine clearance. Therefore, we recommend that this operation be avoided when possible. If the operation is unavoidable, tapering of the ileal segment with antireflux ileovesical anastomosis may improve the outcome. Further clinical study must be done.

The Use of Halofuginone in Limiting Urethral Stricture Formation and Recurrence: An Experimental Study in Rabbits

PURPOSE We developed a reproducible animal model for the induction of urethral stricture in the rabbit and evaluated the role of halofuginone in limiting stricture formation. MATERIALS AND METHODS A total of 20 New Zealand male rabbits were used in the first phase of the experiment. Bulbar urethral stricture was induced by electrocoagulation. The animals were then randomly assigned to 2 groups of 10 each, which received a diet containing halofuginone or a normal diet. In the second phase electrocoagulation induced stricture was treated with visual internal urethrotomy in 45 rabbits. These rabbits were randomly assigned to 2 groups, namely a halofuginone and a control group. RESULTS In the first phase stricture developed in 2 study rabbits (20%) vs 10 controls (100%). In the second phase 37 rabbits were evaluable (8 died). Recurrent stricture was observed in 5 of the 18 study rabbits (27%) vs 14 of the 19 controls (73%). CONCLUSIONS Halofuginone is effective in limiting the occurrence of de novo urethral stricture and recurrent stricture after visual internal urethrotomy. This antifibrotic molecule may become an important therapy to treat urethral stricture and/or recurrence following endoscopic manipulation of stricture in humans.