High-Power Thulium Fiber Laser Ablation of Urinary Tissues at 1.94 µm

PURPOSE

This paper describes the preliminary testing of a new laser, the thulium fiber laser, as a potential replacement for the holmium:YAG laser for multiple applications in urology.

MATERIALS AND METHODS

A 40 W thulium fiber laser operating at a wavelength of 1.94 microm delivered radiation in a continuous-wave or pulsed mode (10 msec) through either 300-microm- or 600-microm-core low-OH silica fibers for vaporization of canine prostate and incision of animal ureter and bladder-neck tissues.

RESULTS

The thulium fiber laser vaporized prostate tissue at a rate of 0.21+/-0.02 g/min. The thermal-coagulation zone measured 500 to 2000 microm, demonstrating the potential for hemostasis. Laser incisions were also made in bladder tissue and ureter, with coagulation zones of 400 to 600 microm.

CONCLUSIONS

The thulium fiber laser has several potential advantages over the holmium laser, including smaller size, more efficient operation, more precise incision of tissues, and operation in either the pulsed or the continuous-wave mode. However, before clinical use will be possible, development of higher-power thulium fiber lasers and shorter pulse lengths will be necessary for rapid vaporization of the prostate and more precise incision of urethral/bladder-neck strictures, respectively.

Use of the holmium:YAG laser in urology

The tissue effects of a holmium:YAG (Ho:YAG) laser operating at a wavelength of 2.1 mu with a maximum power of 15 watts (W) and 10 different energy-pulse settings was systematically evaluated on kidney, bladder, prostate, ureteral, and vasal tissue in the dog. In addition, various urologic surgical procedures (partial nephrectomy, transurethral laser incision of the prostate, and laser-assisted vasovasostomy) were performed in the dog, and a laparoscopic pelvic lymph node dissection was carried out in a pig. Although the Ho:YAG laser has a strong affinity for water, precise tissue ablation was achieved in both the contact and non-contact mode when used endoscopically in a fluid medium to ablate prostatic and vesical tissue. Using the usual parameters for tissue destruction (blanching without charring), the depth of thermal injury in the bladder and ureter was kept superficial. In performing partial nephrectomies, a 2-fold reduction in the zone of coagulative necrosis was demonstrated compared to the use of the continuous wave Neodymium:YAG laser (Nd:YAG). When used through the laparoscope, the Ho:YAG laser provided precise cutting and, combined with electrocautery, allowed the dissection to proceed quickly and smoothly. Hemostatic control was adequate in all surgical procedures. Although the results of these investigations are preliminary, our initial experience with the Ho:YAG laser has been favorable and warrants further investigations.

Neuroanatomy of penile erection: its relevance to iatrogenic impotence

The neuroanatomy of erection in men is not well defined. Recently, we isolated successfully the cavernous nerves for acute and chronic neurostimulation to induce penile erection in dogs and monkeys. We then investigated the anatomy of these nerves in humans by cadaveric dissection and serial histologic sectioning. Our experience in tracing the spinal nuclei responsible for vesical and urethral function by transportation of horseradish peroxidase enabled us to explore the location and organization of the spinal center for erection. Thus, systemic knowledge of the neuroanatomy of erection was accumulated. The spinal nuclei for control of erection are located in the intermediolateral gray matter at the S1 to S3 and T12 to L3 levels in dogs, and the S2 to S4 and T10 to L2 levels in humans. From these sacral nuclei axons issue ventrally and join the axons of the nuclei for the bladder and rectum to form the sacral visceral efferent fibers. These fibers emerge from the anterior root of S2 to S4, and join the sympathetic fibers to form the pelvic plexus, which then branches out to innervate the bladder, rectum and penis. The fibers innervating the penis (cavernous nerves) travel along the posterolateral aspect of the seminal vesicle and prostate, and then accompany the membranous urethra through the genitourinary diaphragm. These fibers are located on the lateral aspect of the membranous urethra and ascend gradually to the 1 and 11 o'clock positions in the proximal bulbous urethra. Some of the fibers penetrate the tunica albuginea of the corpus spongiosum, while others spread to the trifurcation of the terminal internal pudendal artery and innervate the dorsal, deep and urethral arteries. Shortly before the 2 corpora cavernosa merge the cavernous nerves penetrate the tunica albuginea along with the deep artery and cavernous vein. The terminal branches of these nerves innervate the helicine arteries and the erectile tissue within the corpora cavernosa. Because of the intimate relationship of the cavernous nerves to the rectum, prostate and urethra, they can be damaged easily during urological and pelvic procedures. This systemic knowledge of the human cavernous nerves from the spinal center to the erectile tissue should permit a better understanding of erection and impotence. Furthermore, with the aid of intraoperative neurostimulation, the cavernous nerves may be identified and preserved, thereby preventing iatrogenic impotence.

Iatrogenic ureteral injury

We treated 27 patients with iatrogenic ureteral injuries during a 6-year period. Gynecological operations were the most common antecedent surgical procedures (52 per cent). The diagnosis of ureteral injury was made immediately in 4 patients and was delayed 1 to 34 days in 23. Three of the 4 injuries recognized during an operation were repaired successfully at the time of injury; the primary repair in the remaining patient leaked and ultimately resulted in a nephrectomy. In the delayed diagnosis group retrograde ureteral catheterization was successful in only 1 of 20 attempts. Of the 23 patients with injuries recognized in the postoperative period 11 were managed successfully with percutaneous nephrostomy (with or without stenting) alone, 3 required surgical repair after temporary percutaneous nephrostomy drainage, 4 were treated surgically without prior nephrostomy drainage and 1 had spontaneous resolution of hydronephrosis. The remaining 3 patients required nephrectomy: 1 because of a urinary fistula in a previously irradiated field, 1 because of a concomitant (ipsilateral) renal cell carcinoma and 1 because of renal hypertension. Percutaneous nephrostomy or ureteral stenting was successful as primary therapy in 73 per cent of the patients in whom it was used.

A case against incorporation of bowel segments into the closed urinary system

Five patients in whom isolated ileal or ileocecal segments had been incorporated into the urinary tract suffered complications that ended in excision of the bowel segment. A bowel segment functions if it does not meet resistance or increased intraluminal pressures. In a closed system these 2 evils are working constantly against the loop of bowel, subjecting it to growing distension, dilatation and redundancy and, inevitably, residual urine, urinary tract infection, stone formation, electrolyte imbalance and progressive deterioration of the upper urinary tract ensue. What was initially meant to save kidney function causes instead renal damage and eventually total loss of function.

The use of the omental pedicle graft in urinary tract reconstruction-

The omentum is unique in that it is the only body tissue specifically developed for the resolution of infected process; it also regains its suppleness once healing has taken place. The characteristics are not shared by the periureteral and perivesical tissues so that a properly mobilized pedicle graft is valuable adjunct to be more difficult repairs and reconstructions of the urinary tract.

History of Childhood Kidney Disease and Risk of Adult End-Stage Renal Disease

BACKGROUND

The long-term risk associated with childhood kidney disease that had not progressed to chronic kidney disease in childhood is unclear. We aimed to estimate the risk of future end-stage renal disease (ESRD) among adolescents who had normal renal function and a history of childhood kidney disease.

METHODS

We conducted a nationwide, population-based, historical cohort study of 1,521,501 Israeli adolescents who were examined before compulsory military service in 1967 through 1997; data were linked to the Israeli ESRD registry. Kidney diseases in childhood included congenital anomalies of the kidney and urinary tract, pyelonephritis, and glomerular disease; all participants included in the primary analysis had normal renal function and no hypertension in adolescence. Cox proportional-hazards models were used to estimate the hazard ratio for ESRD associated with a history of childhood kidney disease.

RESULTS

During 30 years of follow-up, ESRD developed in 2490 persons. A history of any childhood kidney disease was associated with a hazard ratio for ESRD of 4.19 (95% confidence interval [CI], 3.52 to 4.99). The associations between each diagnosis of kidney disease in childhood (congenital anomalies of the kidney and urinary tract, pyelonephritis, and glomerular disease) and the risk of ESRD in adulthood were similar in magnitude (multivariable-adjusted hazard ratios of 5.19 [95% CI, 3.41 to 7.90], 4.03 [95% CI, 3.16 to 5.14], and 3.85 [95% CI, 2.77 to 5.36], respectively). A history of kidney disease in childhood was associated with younger age at the onset of ESRD (hazard ratio for ESRD among adults <40 years of age, 10.40 [95% CI, 7.96 to 13.59]).

CONCLUSIONS

A history of clinically evident kidney disease in childhood, even if renal function was apparently normal in adolescence, was associated with a significantly increased risk of ESRD, which suggests that kidney injury or structural abnormality in childhood has long-term consequences.

Impact of Sex Reassignment Surgery on Lower Urinary Tract Function

OBJECTIVE

To investigate the effects of sex reassignment surgery (SRS) on lower urinary tract function.

METHODS

A questionnaire concerning voiding habits and lower urinary tract symptoms after sex reassignment surgery, was given to 24 female-to-male transsexuals (FTM) and 31 male-to-female transsexuals (MTF), who respectively underwent phalloplasty and vaginoplasty. For this study only Dutch speaking patients were selected. Also, uro-flowmetry data from 92 FTM transsexuals were reviewed.

RESULTS

In general, no change in voiding patterns was observed. Post-void dribbling was reported by 79% of the FTM transsexuals, and 16% of the MTF group reported some form of incontinence. The uro-flowmetry examination showed a mean, non-significant decrease of 2 ml/s in Q(max) in FTM patients.

CONCLUSION

SRS can cause minor changes in urinary habits. Even if they do not result in patients seeking medical help, transsexuals should be warned about these eventual discomforts pre-operatively.

Indwelling double-J ureteral stents for temporary and permanent urinary drainage: experience with 87 patients

Indwelling ureteral stents are a useful addition to the urologic armamentarium. The current double-J ureteral stent offers the advantages of ease of endoscopic insertion, exceptional patient tolerance and improved resistance to incrustation. We used these stents in 87 patients: to bypass obstruction in 57, as an adjunct to complicated upper tract surgery in 15, as initial treatment of upper urinary fistulas in 10 and for miscellaneous reasons in 5. The majority of the stents were placed endoscopically (58 per cent) and under local anesthesia (54 per cent). Half of the urinary fistulas healed without an operation and none of the patients treated with stents for malignant obstruction was hospitalized for more than 4 days. The stents were changed easily on an outpatient basis under local anesthesia and patient tolerance was excellent. When used as adjuncts to open procedures the stents frequently allowed for shorter hospital stay, since postoperative urinary drainage was decreased markedly. Of the 136 stents used in our series 13 became obstructed, usually after they were indwelling for more than 8 weeks. Irritative symptoms were noted in only 6 patients and responded well to pharmacologic therapy. We have found the double-J ureteral stent useful and reliable in patients with ureteral obstruction, as adjuncts to genitourinary surgery in selected instances and as internal diversion for upper urinary tract fistulas.

Pelvic fracture and associated urologic injuries

Successful management of patients with major pelvic injuries requires a team approach including orthopedic, urologic, and trauma surgeons. Each unstable pelvic disruption must be treated aggressively to minimize complications and maximize long-term functional outcome. Commonly associated urologic injuries include injuries of the urethra, corpora cavernosa (penis), bladder, and bladder neck. Bladder injuries are usually extraperitoneal and result from shearing forces or direct laceration by a bone spicule. Posterior urethral injuries occur more commonly with vertically applied forces, which typically create Malgaigne-type fractures. Common complications of urethral disruption are urethral stricture, incontinence, and impotence. Acute urethral injury management is controversial, although it appears that early primary realignment has promise for minimizing the complications. Impotence after pelvic fracture is predominantly vascular in origin, not neurologic as once thought.

The role of renal autotransplantation in complex urological reconstruction

From 1972 to 1988, 108 patients underwent renal autotransplantation for renal artery disease (67), ureteral replacement (27), or renal cell carcinoma present bilaterally or in a solitary kidney (14). The most common indication for renal autotransplantation was to allow extracorporeal repair of complex branch renal artery lesions. Of the 54 patients in this group technically satisfactory branch renal arterial reconstruction and a successful clinical outcome were achieved in 52 (96%). Renal autotransplantation is the treatment of choice in these patients and also in selected children with main renal artery disease. Renal autotransplantation provided excellent results in 25 of 27 patients (92%) who required replacement of all or a major portion of the ureter. Over-all renal function was well preserved in these patients and only 1 has experienced chronic bacteriuria. Renal autotransplantation is a useful alternative to ileal interposition in this setting. Extracorporeal partial nephrectomy and renal autotransplantation were successful in 12 of 14 patients (85%) undergoing a nephron-sparing operation for renal cell carcinoma. In situ techniques are associated with less morbidity and currently are preferred in this group.

Fetal lower urinary tract obstruction

Fetal lower urinary tract obstruction affects 2.2 per 10,000 births. It is a consequence of a range of pathological processes, most commonly posterior urethral valves (64%) or urethral atresia (39%). It is a condition of high mortality and morbidity associated with progressive renal dysfunction and oligohydramnios, and hence fetal pulmonary hypoplasia. Accurate detection is possible via ultrasound, but the underlying pathology is often unknown. In future, magnetic resonance imaging (MRI) may be increasingly used alongside ultrasound in the diagnosis and assessment of fetuses with lower urinary tract obstruction. Fetal urine analysis may provide improvements in prenatal determination of renal prognosis, but the optimum criteria to be used remain unclear. It is now possible to decompress the obstruction in utero via percutaneous vesico-amniotic shunting or cystoscopic techniques. In appropriately selected fetuses intervention may improve perinatal survival, but long-term renal morbidity amongst survivors remains problematic.

Secreto-motor function of intestinal segments used in lower urinary tract reconstruction

Mucus excretion, sialic acid excretion and secretory IgA (sIgA) production from patients with a substitution caecocystoplasty (20), augmentation "clam" ileocystoplasty (20) or ileal conduit (10) were measured. Significant amounts of all of these substances were present in the urine of reconstructed patients and showed no evidence of diminution with time. Motility was studied by videocystourethrography. In patients with a neuropathic aetiology the amplitude of contractions was significantly increased and produced incontinence. The results demonstrate that intestinal secreto-motor function in gut segments incorporated into the lower urinary tract continues normally and must be taken into account when considering the long-term management of these patients.

An assessment of a collagen/vicryl composite membrane to repair defects of the urinary bladder in rabbits

Collagen/vicryl (Polyglactin) composite membrane has been used to repair full-thickness defects in the urinary bladder of rabbits. The material has been shown to be biodegradable, prevent leakage of urine, and is readily replaced by collagenous scar tissue lined with a urothelium. Regeneration of smooth muscle has been observed in the repair area of some animals. The results suggest that such a material may well be of use to urologists wishing to augment contracted bladders or in the repair of bladder fistulae in human subjects, thereby avoiding the use of bowel or other material e.g. omentum.

Organ-specific acellular matrix for reconstruction of the urinary tract

In urology, replacement of organs or organ segments has proved problematic. Current techniques do not replicate complete organ function, and they cause well-known complications. With the acellular organ-specific matrix we have found a way to regenerate tissue components seen in the normal lower urinary tract. The time required for regeneration depends on the matrix size and function. The matrix is covered by urothelium migrating from the host, after which neovascularization occurs, followed by formation of smooth-muscle cells and nerves. In our studies, normal muscle lining and nerves providing functional tissue were demonstrable and no sign of antigenicity was evident, even after heterologous grafting. The regenerated rat bladder was evaluated by organ bath as well as by in vivo functional tests and demonstrated properties and functions similar to those of host tissue. Besides our obtaining encouraging results in the rat bladder, we also studied the organ-specific acellular matrix in other species (dog and rabbit) and other organ segments (ureter and urethra).

Application of argon beam coagulation in urological surgery

Argon beam coagulation is a new form of electrocautery that has proved useful to control diffuse bleeding in other surgical specialties. We report its application to urology. Three cases are presented in which argon beam coagulation provided excellent hemostasis in situations that are often difficult to control, such as partial nephrectomy for penetrating trauma, hemorrhagic cystitis refractory to other forms of treatment and after anterior exenteration for bladder cancer. The basis, technique and advantages of argon beam coagulation are discussed, as well as other instances in urological surgery in which it may have application. Argon beam coagulation is an alternative to conventional methods of hemostasis whenever there is a diffusely bleeding operative site.

External urethral sphincterotomy: long-term follow-up

We retrospectively reviewed the charts of 37 male spinal cord injury patients who underwent sphincterotomy from 1986-1993 to evaluate the long-term results of this procedure. Patients were selected for the operation based on urodynamic criteria and all had some detrusor activity or were able to void by Valsalva's maneuver. There were 26 cervical injuries and 11 thoracic injuries. The operation was judged a failure if the following were present postoperatively: the presence of large post void residual volumes associated with urinary tract infections, autonomic dysreflexia symptoms associated with bladder overdistension or high voiding pressures, and/or progressive upper tract deterioration due to persistent vesicoureteral reflux or poor bladder emptying. Eighteen' operations were failures and 19 operations were successful. Causes for sphincterotomy failure included recurrent detrusor sphincter dyssynergy (6), detrusor hypocontractility (6), bladder neck contracture (3), stricture at the external sphincter (1), incomplete sphincterotomy (1), and unknown etiology (1). The reoperation rate was 32%. The mean follow-up time was 49 months for the failure group (range 2-81) and 26 months (range 2-54) for the successes. The longer mean follow-up period in the former group suggests that the number of failures increased with time. There was no predictor of failure among any of the following parameters: age at operation, level of injury, previous bladder neck/sphincter operations, preoperative maximum detrusor contraction pressures, or rise time to maximum pressure.

IN CONCLUSION

(1) the external urethral sphincterotomy, even in appropriately selected patients, can have a high failure rate over time, and (2) we could not identify any variables to predict an unsuccessful operation using our present selection criteria.

Urodynamics

Urologic problems constitute a very significant percentage of all clinical problems in pediatrics. Incorporation of urodynamic evaluation and followup is important in achieving optimal results in a significant number of these entities. In terms of cost effectiveness, it is particularly efficient in this age of extremely high-priced technology.

Management of children with urinary tract infections: the Stanford experience

Two hundred seventy-eight female children with urinary tract infections have been evaluated at Stanford division of urology. All children were followed up for a period of not less than twelve months. Age of onset of infection, clinical presentation, and nature of infecting organisms were observed. The group consisted of 144 children without ureteral reflux and 134 children with ureteral reflux. Sixty-one of the female children with ureteral reflux had ureteral reimplantation, while 73 received medical treatment alone. A study of infection rates in each of the three groups of children indicated a similar infection rate, although those children with reflux experienced a higher incidence of clinical pyelonephritis. Correction of ureteral reflux did not alter the infection rate; however, infections after surgical correction were generally of a type usually associated with children without reflux. Twenty-nine children had urethral dilatation, and the infection rate prior to and following urethral dilatation indicated a similar rate of infection pre- and posturethral dilatation. One hundred nonrefluxing kidneys were observed radiologically: 97 were normal and 3 showed clubbing and scarring. Of 110 refluxing renal units observed, 62 were clubbed and scarred and 48 were normal. Following surgical correction of reflux, renal clubbing and scarring were not observed in previously normal renal units. Of those renal units found to be abnormal at time of surgery, 66 per cent showed progression of clubbing and scarring after surgical correction of reflux. It was observed that the greater the degree of reflux present, the higher the incidence of renal damage. This study suggests that children who experience recurrent urinary tract infections who do not have ureteral reflux are seldom at renal risk; similar children who do have ureteral reflux are at risk unless the infections are controlled or the reflux either disappears or is corrected surgically.