Scaling laws for step bunching on vicinal surfaces: Role of the dynamical and chemical effects

We study the evolution of step bunches on vicinal surfaces using a thermodynamically consistent step-flow model. By accounting for the dynamics of adatom diffusion on terraces and attachment-detachment at steps (referred to collectively as the dynamical effect), this model circumvents the quasistatic approximation that prevails in the literature. Furthermore, it generalizes the expression of the step chemical potential by incorporating the necessary coupling between the diffusion fields on adjacent terraces (referred to as the chemical effect). Having previously shown that these dynamical and chemical effects can explain the onset of step bunching without recourse to the inverse Ehrlich-Schwoebel (iES) barrier or other extraneous mechanisms, we are here interested in the evolution of step bunches beyond the linear-stability regime. In particular, the numerical resolution of the step-flow free boundary problem yields a robust power-law coarsening of the surface profile, with the bunch height growing in time as H∼t^{1/2} and the minimal interstep distance as a function of the number of steps in the bunch cell obeying ℓ_{min}∼N^{-2/3}. Although these exponents have previously been reported, the novelty of the present approach is that these scaling laws are obtained in the absence of an iES barrier or adatom electromigration. In order to validate our simulations, we take the continuum limit of the discrete step-flow system via Taylor expansions with respect to the terrace size, leading to a novel nonlinear evolution equation for the surface height. We investigate the existence of self-similar solutions of this equation and confirm the 1/2 coarsening exponent obtained numerically for H. We highlight the influence of the combined dynamical-chemical effect and show that it can be interpreted as an effective iES barrier in the setting of the standard Burton-Cabrera-Frank theory. Finally, we use a Padé approximant to derive an analytical expression for the velocity of steadily moving step bunches and compare it to numerical simulations.

Stability of Vicinal Surfaces: Beyond the Quasistatic Approximation

We revisit the step bunching instability without recourse to the quasistatic approximation and show that the stability diagrams are significantly altered, even in the low-deposition regime where it was thought sufficient. In particular, steps are unstable against bunching for attachment-detachment limited growth. By accounting for the dynamics and chemical effects, we can explain the onset of step bunching in Si(111)-(7×7) and GaAs(001) without resort to the inverse Schwoebel barrier or step-edge diffusion. Further, the size-scaling analysis of step-bunch growth, as induced by these two combined effects, agrees with the bunching regime observed at 750 °C in Si(111)-(7×7).

[Conservative treatment of upper urinary tract tumors]

The histological appearance and the clinical behaviour of upper urinary tract urothelial tumours are almost identical to those of the bladder. Superficial papillary tumours rarely progress and turn to invasive disease despite a high frequency of recurrence. Technical developments in the endourology field have allowed full endoscopic access to upper tract tumours. Endoscopic resection or ablation of the tumour can be undertaken safely and effectively through ureteroscopy or percutaneous nephroscopy with low risk of extra-renal tumour seeding. For superficial (Ta, T1), low grade (I, II) tumours, a conservative approach can be selected without compromising survival and prognosis. For muscle invasive > T2 or high grade (III) tumours, nephroureterectomy remains the treatment of choice. Intracavitary BCG used after percutaneous resection reduces the risk of recurrence of upper tract urothelial tumours regardless of the grade. Finally, the world literature and our personal experience have shown that the tumour grade and stage are the two independent factors that affect survival of patients with upper urinary tract tumours.

Percutaneous implantation of subcutaneous prosthetic ureters: long-term outcome

PURPOSE

We have used an extra-anatomic subcutaneous alloplastic ureteral replacement initially to bypass ureteral obstruction secondary to advanced pelvic malignancies in patients with a short life expectancy. Following the encouraging preliminary results, our list of indications has broadened to include complex benign ureteral strictures. We herein report the long-term outcome.

PATIENTS AND METHODS

A series of 35 subcutaneous prosthetic ureters were implanted percutaneously in 27 patients (19 unilateral and 8 bilateral) to bypass extrinsic ureteral obstructions. The nature of obstruction was neoplastic in 22 patients and benign in 5. A composite prosthesis, consisting of two coaxial tubes--internal pure smooth silicone covered by coiled e-PTFE--has been designed to serve as the ureteral replacement. This tube is inserted percutaneously into the renal pelvis, tunnelled subcutaneously, and introduced through a small suprapubic incision in the bladder. All patients were followed to date or until death from tumor. The mean follow-up was 6.3 months for the deceased patients and 47 months for the surviving ones, the longest follow-up being 84 months.

RESULTS

No operative or immediate postoperative deaths were observed. Initial difficulty in placing the prosthesis was encountered in 5 of the 27 patients (19%). Secondary parietal complications occurred in 8.5% of cases (3/35). The prosthetic ureter had to be removed in one patient because of skin erosion. Return to a standard percutaneous nephrostomy was needed in two patients because of local tumor progression with bladder fistulae. Five patients are alive with the prosthesis in place and a follow-up as long as 84 months without encrustation, infection, obstruction, or skin problems and with normally functioning kidneys.

CONCLUSION

The subcutaneous urinary diversion using a silicone-PTFE prosthesis is an efficient and minimally invasive way to bypass malignant or complex benign obstructions of the ureters that otherwise would necessitate permanent nephrostomy drainage.

Endopyelotomy failure is associated with reduced urinary transforming growth factor-beta1 levels in patients with upper urinary tract obstruction

BACKGROUND AND PURPOSE

We previously demonstrated that obstructed ureteropelvic junction (UPJ) segments from patients who had secondary pyeloplasty after endopyelotomy failure expressed transforming growth factor-beta1 (TGF-beta1) at levels significantly lower than patients who had primary pyeloplasty. In order to determine whether these differences in secreted TGF-beta1 are detectable preoperatively in the urine, the TGF-beta1 concentration of urine from patients undergoing endopyelotomy was determined and compared with that from subjects without urologic disease.

MATERIALS AND METHODS

Bladder and renal pelvic urine from the obstructed side was obtained from patients (N = 34) undergoing primary endopyelotomy for UPJ obstruction. Bladder urine was also obtained from sex- and age-matched patients (N = 26) having no evidence of urinary tract obstruction. The TGF-beta1 concentration was determined by ELISA and normalized to the creatinine concentration.

RESULTS

The bladder urine TGF-beta1 concentration was significantly (P < 0.02) higher in patients with UPJ obstruction (86.1+/-20.5 pg/mg of creatinine) than in those without obstruction (29.7+/-8.0 pg/mg creatinine). The TGF-beta1 concentration in the bladder urine of patients who underwent endopyelotomy and later returned because of UPJ obstruction (25.7+/-12.3 pg/mg of creatinine; N = 6) was not significantly different from the value in unobstructed patients but was significantly lower (P < 0.01) than in patients for whom endopyelotomy was successful (100+/-24.29 pg/mg of creatinine; N = 28). The renal pelvic urinary TGF-beta1 concentration was higher in patients for whom endopyelotomy was successful (772+/-490.1 pg/mg of creatinine) than in patients who underwent endopyelotomy and later returned because of UPJ obstruction (126.1+/-41.9 pg/mg of creatinine).

CONCLUSIONS

These data suggest that preoperative concentration of TGF-beta1 in the bladder urine of patients with UPJ obstruction who fail endopyelotomy is not significantly different from that in subjects with no urologic disease and significantly lower than in those patients for whom endopyelotomy is successful. Thus, the preoperative bladder urine concentration of TGF-beta1 may assist in selecting patients for this operation, although further investigation is necessary.

Primary percutaneous approach to upper urinary tract transitional cell carcinoma

The optimal approach to upper tract TCC remains to be redefined. A routine nephroureterectomy for every filling defect in the upper urinary system, even in the case of a normal contralateral kidney, constitutes an unnecessary mutilation in more than two thirds of the cases. Nephroureterectomy does not reduce the need for a long-term cystoscopic follow-up because of the high rate of bladder tumor recurrence that may happen years later after nephroureterectomy. Relying solely on radiography and cytology, lacking sensitivity and specificity, to recommend a nephroureterectomy is against the principles of oncologic surgery, especially now that preoperative histologic proof is easy to obtain endoscopically without compromising cancer control. Ureteroscopy, rigid and flexible, provides a complete assessment of the upper urinary system. Biopsy specimens taken with ureteroscopy may be sufficient for grading but less adequate for staging of the tumor. The authors reserve ureteroscopy for ureteral tumors and small (< 1.5 cm) single tumors of the renal pelvis. They approach large or multiple tumors of the renal pelvis percutaneously, in which a full histologic assessment is possible along with a complete resection of the tumor. The decision on the therapeutic approach is made only after the final pathologic report is reviewed. Grade I and grade II superficial disease (Ta, T1) can be treated endoscopically with minimal morbidity and with an efficiency comparable with the standard more invasive nephroureterectomy (Table 5). The indications for endourologic treatment in these cases can be extended safely beyond a solitary kidney or a high surgical risk to include any healthy individual with a normal contralateral kidney who is willing to commit to a rigorous lifelong follow-up. Patients with grade II T1 lesions require a more vigilant follow-up. For grade III Ta disease, more caution should be exercised in selecting these patients for elective endourologic management. When criteria of good prognosis are found, such as absence of carcinoma in situ, presence of diploidy, low p53 expression and a single-tumor, endoscopic management can be offered [table: see text] with a closer follow-up and resorting always to immediate nephroureterectomy at the first evidence of upstaging. Because of the high incidence of recurrence and progression, elective endourologic management for grade III T1 tumors is not recommended. Endoscopic conservative surgery still can be offered in the cases of a solitary kidney or chronic renal insufficiency or for poor surgical candidates. Patients with localized stages (T2, T3) TCC should be offered immediate nephroureterectomy. The authors do not expect adequate endoscopic extirpation with muscle invasive tumors. Although the tissue removed may include deep layers, deep resection is precluded by the thin renal pelvic wall and the associated risk for perforation. Patients with more extensive disease (T3, T4) have a bad prognosis regardless of the form of therapy. Achieving local control percutaneously while preserving as many nephrons as possible for the future chemotherapy can be a reasonable option.

Percutaneous management of grade II upper urinary tract transitional cell carcinoma: the long-term outcome

PURPOSE

We report the long-term outcome of our experience with percutaneous treatment of grade II upper urinary tract transitional cell carcinoma.

MATERIALS AND METHODS

A total of 61 patients with transitional cell carcinoma of the upper urinary tract were treated percutaneously between 1984 and 1998. Of the patients 24 (39%) had grade II disease. Immediate nephroureterectomy was performed due to muscle invasive disease in 2 patients, bleeding in 1 and inability to resect the whole tumor in 1. Percutaneous resection was the actual treatment in 15 patients with stage Ta and 5 with stage T1 disease.

RESULTS

Recurrence was noted in 5 patients (25%), including 3 (20%) with stage Ta tumors and 2 (40%) with stage T1 disease after a median followup of 48 months (range 9 months to 12 years). All stage Ta disease recurrences were superficial. In 1 patient with a stage T1 tumor invasive and metastatic disease developed. Disease specific survival was 95% overall, and 100% for stage Ta and 80% for stage T1 disease. No tumor seeding was detected along the percutaneous tract.

CONCLUSIONS

Percutaneous surgery has proved safe and effective in treating superficial grade II upper tract transitional cell carcinoma. Offering an endoscopic approach electively to healthy individuals with a normal contralateral kidney seems viable.

Acute ureteral elongation in two animal models using a balloon expander

BACKGROUND AND OBJECTIVE

Repair of ureteral injuries and strictures often necessitates a major reconstructive procedure such as a psoas hitch, Boari flap, renal mobilization, ileal interposition, or autotransplantation. Tissue expanders have been used to elongate nerves and arteries. We examined the effects of acute ureteral elongation in two animal models.

MATERIALS AND METHODS

In eight female rabbits, we exposed the left ureter through a midline incision and placed a Ruiz-Cohen balloon beneath the undermined portion. The expander was then inflated until the ureter was tightly stretched across it. After deflation, the expanded segment was measured in situ and compared with its original length. Follow-up urography was performed, and the tissue was harvested and examined by a pathologist. The same procedure was performed in five pigs; however, in these animals, a segment of ureter was excised, and a ureteroureterostomy was performed, after the acute expansion.

RESULTS

We were able to achieve acute elongation of the expanded ureteral segment. The mean elongation was 31.3% in the rabbits and 32.0% in the pigs. An intravenous urogram (IVU) 6 weeks after the elongation showed a functioning kidney and a patent ureter. Histologic examination of the ureter within 24 hours after the expansion revealed that all segments were viable, the luminal epithelium was intact, and the muscular layers appeared normal. At 6 weeks, the expanded segment showed mild inflammatory changes, but the overall morphology, size, and cytology findings were similar to those of a normal control.

CONCLUSIONS

Acute ureteral elongation using a tissue expander is a new method of increasing ureteral length. It may be useful to cover defects that would need major operations with greater morbidity.

Failed endopyelotomy: low expression of TGF beta regardless of the presence or absence of crossing vessels

BACKGROUND AND OBJECTIVE

Endopyelotomy relies on Davis' intubated ureterotomy principle of healing by secondary intention and smooth-muscle regeneration. Approximately 15% of endopyelotomies fail, and the restrictured segment almost always shows evidence of reactive fibrosis with little smooth-muscle regeneration. Previous data suggests that an elevation of TGF beta in obstructed ureteropelvic junctures may be necessary for successful tissue repair following endopyelotomy. The role of crossing vessels in endopyelotomy failure is very controversial. To better understand the pathophysiology of endopyelotomy failure, the expression of transforming growth factor-beta (TBG beta) in patients with a failed endopyelotomy and crossing vessels was compared with that in patients without crossing vessels, as well as those having primary pyeloplasty or a normal ureteropelvic junction (UPJ).

MATERIALS AND METHODS

The expression of TGF beta was detected immunohistochemically in slide-mounted thin sections (4 microns) cut from paraffin-blocked adult UPJ segments obtained during primary pyeloplasty (N = 11), secondary pyeloplasty after failed endopyelotomy with documented crossing vessels (N = 10), secondary pyeloplasty after failed endopyelotomy without crossing vessels (N = 11), and normal UPJs removed during nephrectomy for purposes unrelated to obstruction (N = 11). Expression was graded on a scale of 0 to 4.

RESULTS

The combined failed endopyelotomy group had a significantly (P < 0.05) lower level of TGF beta (1.9 +/- 0.7) than did primary obstructed UPJs (2.6 +/- 0.7). The TGF beta level in the crossing vessels group (1.9 +/- 0.7) did not differ from that in the group without crossing vessels (1.8 +/- 0.7), nor did it differ from that in the group with normal UPJs (1.6 +/- 0.7). As expected, primary obstructed UPJs had a significantly higher level of TGF beta than normal ones (P < 0.02).

CONCLUSIONS

Obstructed UPJs that had failed endopyelotomy had a similarly reduced level of TGF beta whether or not crossing vessels were present. These data suggest that an elevation of TGF beta in obstructed UPJs may be necessary for successful tissue repair after endopyelotomy and that the presence of crossing vessels is probably not relevant.

13-year survival comparison of percutaneous and open nephroureterectomy approaches for management of transitional cell carcinoma of renal collecting system: equivalent outcomes

BACKGROUND AND OBJECTIVE

Transitional cell carcinoma (TCC) of the renal collecting system traditionally has been managed by open nephroureterectomy with en bloc resection of a bladder cuff. However, for a select patient population with a solitary kidney or bilateral disease, the morbidity and mortality associated with chronic renal insufficiency and dialysis is deterring. In these situations, a more conservative approach such as antegrade percutaneous resection should be considered. The long-term disease-free outcome of percutaneous management in comparison with open nephroureterectomy has not been previously reported. We evaluated our experience with two surgical approaches to treat upper tract TCC: percutaneous resection and nephroureterectomy/nephrectomy to assess the clinical efficacy of these surgical modalities.

PATIENTS AND METHODS

We retrospectively identified 162 patients who had clinically localized TCC of the upper urinary tract. Records were reviewed to identify those with 13-year follow-up (N = 110) in respect to tumor grade, stage, disease-free status, length of cancer-specific survival, and overall survival. Statistical analysis of the results of open nephroureterectomy/nephrectomy (N = 60) and percutaneous resection (N = 50) was performed using Kaplan-Meier survival curves and Student's t-test.

RESULTS

All patients had disease in clinical stage Ta through T3. During a mean follow-up of 46.6 (range 6-150) months, grade 1 disease demonstrated little invasive potential. Of the disease-specific deaths, 60% (17/26) were of patients with grade 3 lesions, with a mean cancer survival period of 15.2 months after the initial procedure. Disease-specific survival rates after open and percutaneous approaches for grade 2 disease were 53.8 and 53.3 months, respectively (P > 0.05).

CONCLUSIONS

Tumor grade appeared to be the most important prognostic indicator in patients with renal TCC regardless of the surgical approach. Grade 3 tumors were more aggressive, presenting in an advanced stage with invasion, and recurrences were usually associated with metastasis. In this population, nephroureterectomy is warranted if the patient is a surgical candidate. The percutaneous option for grade 1 or 2 disease may be extended beyond the population with solitary kidneys and a risk of chronic renal failure to be offered to healthy individuals with normal contralateral kidneys who are willing to abide by a strict and lengthy follow-up.

A 3 trocar technique for transperitoneal laparoscopic nephrectomy

PURPOSE

Additional trocars and retractor instruments may enhance the risk of iatrogenic injuries during laparoscopic nephrectomy. We describe a modified technique of laparoscopic nephrectomy requiring only 3 ports of entry and no extra instruments instead of the 5 ports, 2 of which are used for retractors, usually required.

MATERIALS AND METHODS

With the patient in full flank position a 10 mm. trocar is inserted between the umbilicus and subcostal margin, a 5 mm. trocar is placed subcostal in the midclavicular line and a 12 mm. trocar is inserted over the iliac crest in the anterior axillary line. The first step is incision of the line of Toldt and medial reflection of the colon. During the second step of vascular controls the posterosuperior attachments of the kidney are left untouched, keeping the renal vessels stretched, with no need for an extra instrument. The third step consists of severing the remaining posterior and superior attachments of the kidney followed by specimen retrieval. A total of 14 consecutive patients underwent laparoscopic nephrectomy with this technique.

RESULTS

All 14 procedures were completed without an additional port. There were no intraoperative or postoperative complications, except 1 abdominal wall hematoma. Mean operating time was 120 minutes (range 70 to 230) and mean hospital stay was 5 days (range 3 to 7).

CONCLUSIONS

Transperitoneal laparoscopic nephrectomy with laparoscopic access limited to 3 trocars is a reliable and safe technique.

Endopyelotomy failure is associated with reduced transforming growth factor-beta

PURPOSE

Approximately 15% of patients with ureteropelvic junction obstruction have endopyelotomy failure and require an additional surgical procedure to remove the obstruction. Transforming growth factor-beta (TGF-beta), a cytokine which stimulates mesenchymal cell proliferation and extracellular matrix deposition, increases in the renal pelvis in response to obstruction. However, TGF-beta also is implicated in smooth muscle regeneration and wound healing. To understand the pathophysiology of ureteropelvic junction obstruction and determine why endopyelotomy fails in some obstructed ureteropelvic junctions, TGF-beta expression in obstructed and normal ureteropelvic junction segments was compared.

MATERIALS AND METHODS

Immunohistochemical staining using a rabbit polyclonal anti-TGF-beta was performed on deparafinfized 4 microm. sections of paraffin blocked ureteropelvic junction segments. Human obstructed ureteropelvic junction segments were removed during primary pyeloplasties (11) and secondary pyeloplasties after endopyelotomy failure (11). Normal ureteropelvic junction segments were removed during nephrectomy for purposes unrelated to obstruction (11). Grading on a scale of 0 to 4 was performed by a physician blinded to the source of the specimen.

RESULTS

Mean TGF-beta expression plus or minus standard error of the mean was significantly increased (p <0.02) in obstructed ureteropelvic junctions from primary pyeloplasties (2.6+/-0.7) compared to normal ureteropelvic junctions (1.6+/-0.7), as expected. However, TGF-beta expression in the endopyelotomy failure group (1.8+/-0.6) was not significantly different from that in normal ureteropelvic junctions and was significantly lower (p <0.05) than that in obstructed ureteropelvic junctions from primary pyeloplasties.

CONCLUSIONS

Obstructed ureteropelvic junctions in cases of endopyelotomy failure have decreased expression of TGF-beta compared with other obstructed ureteropelvic junctions. These data suggest that an elevation of TGF-beta in obstructed ureteropelvic junctions may be necessary for successful tissue repair after endopyelotomy.

Endopyelotomy for horseshoe and ectopic kidneys

PURPOSE

We report our experience with endopyelotomy for horseshoe and ectopic kidneys in the largest series to date to our knowledge, and discuss the technical modifications adopted to perform successfully percutaneous antegrade endopyelotomy.

MATERIALS AND METHODS

From September 1987 to April 1996, 4 patients with horseshoe and 5 with ectopic kidney underwent percutaneous antegrade endopyelotomy for symptomatic ureteropelvic junction obstruction. The percutaneous puncture was made more posteromedial and the ureteropelvic junction was incised lateral. A retrograde percutaneous access tract was created under laparoscopic guidance in pelvic kidneys.

RESULTS

The operative procedure was performed uneventfully in all patients with no major bleeding, pleural effusion or visceral perforation. The stents were removed at 6 weeks, and an excretory urogram was performed at 2 weeks, 6 months and yearly thereafter. In 2 patients (22%) with severe hydronephrosis, poor renal function and a long ureteral stricture surgical treatment failed immediately. The remaining 7 patients (78%) had long lasting clinical and radiographic success with a mean followup of 62 months.

CONCLUSIONS

Percutaneous antegrade endopyelotomy, with a few technical modifications, is a safe and effective treatment for ureteropelvic junction obstruction associated with horseshoe and ectopic kidneys.

Endopyelotomy after failed pyeloplasty: the long-term results

PURPOSE

Endopyelotomy has been proposed as a technique to treat ureteropelvic junction obstruction after failed open pyeloplasty. However, to our knowledge no long-term results of this treatment have been reported. We report the long-term followup of a cohort of patients in whom pyeloplasty failed and who subsequently were treated with endopyelotomy.

MATERIALS AND METHODS

From January 1985 to February 1996, 72 patients in whom open surgical pyeloplasty failed were treated with percutaneous endopyelotomy. Mean patient age was 35 years (range 5 to 82). The interval between pyeloplasty and subsequent failure ranged from 2 months to 30 years (mean 57 months). The major presenting symptoms were pain in 82% of cases, fever and urinary tract infections in 37.5%, stone formation in 25% and gross hematuria in 21%.

RESULTS

Antegrade endopyelotomy using a hooked knife was performed in all patients with no unusual difficulty and minimal complications. A total of 63 patients (87.5%) had long lasting clinical and radiographic treatment success after a mean followup of 88.5 months. Of the 9 endopyelotomy failures (12.5%) 7 (77.8%) were detected immediately after stent removal at 6 weeks, 1 (11.1%) at 6 months and 1 (11.1%) at 10 months postoperatively (mean failure interval 3.3 months). The failures were corrected with repeat endopyelotomy in 1 patient, pyeloplasty in 3, ileal interposition in 1 and nephrectomy in 4.

CONCLUSIONS

Endopyelotomy is the treatment of choice for recurrent ureteropelvic junction obstruction after failed pyeloplasty, with a high and sustained long-term success rate and no reported new failures after 1-year followup. Furthermore, endopyelotomy is technically easier with less morbidity than repeat open pyeloplasty.

Endopyelotomy for horseshoe and ectopic kidneys

PURPOSE

We report our experience with endopyelotomy for horseshoe and ectopic kidneys in the largest series to date to our knowledge, and discuss the technical modifications adopted to perform successfully percutaneous antegrade endopyelotomy.

MATERIALS AND METHODS

From September 1987 to April 1996, 4 patients with horseshoe and 5 with ectopic kidney underwent percutaneous antegrade endopyelotomy for symptomatic ureteropelvic junction obstruction. The percutaneous puncture was made more posteromedial and the ureteropelvic junction was incised lateral. A retrograde percutaneous access tract was created under laparoscopic guidance in pelvic kidneys.

RESULTS

The operative procedure was performed uneventfully in all patients with no major bleeding, pleural effusion or visceral perforation. The stents were removed at 6 weeks, and an excretory urogram was performed at 2 weeks, 6 months and yearly thereafter. In 2 patients (22%) with severe hydronephrosis, poor renal function and a long ureteral stricture surgical treatment failed immediately. The remaining 7 patients (78%) had long lasting clinical and radiographic success with a mean followup of 62 months.

CONCLUSIONS

Percutaneous antegrade endopyelotomy, with a few technical modifications, is a safe and effective treatment for ureteropelvic junction obstruction associated with horseshoe and ectopic kidneys.

Necrosis of the urethra and tissue sloughing: a delayed complication after transurethral microwave thermotherapy

Transurethral microwave thermotherapy is a minimally invasive treatment for benign prostatic hyperplasia designed to destroy hyperplastic tissue without damaging the urethra. We present an unexpected complication of prostatic urethral necrosis and tissue sloughing after thermotherapy and discuss its possible cause.

Percutaneous removal of stone from caliceal diverticulum in patient with nephroptosis

A novel method is introduced for percutaneous stone extraction from a lower pole caliceal diverticulum in a patient with nephroptosis, also known as a floating kidney. The patient was fully recovered and asymptomatic at 2 months postoperatively with her kidney fixed in the flank position.

Transurethral microwave thermotherapy for management of benign prostatic hyperplasia: a single-institution experience

OBJECTIVES

This is the first and largest single institution retrospective study in the United States to examine the effects of transurethral microwave thermotherapy (TUMT) for the treatment of benign prostatic hyperplasia (BPH).

METHODS

From September 1996 to June 1997, 78 men with moderate to severe symptomatic BPH were treated with the Prostatron at our institution. Patient age ranged from 52 to 85 years. Prostate volume ranged from 23 to 110 cc, and mean total energy applied during the treatment was 156.17 kJ. Patients were re-evaluated at 3 months and were asked to answer a questionnaire regarding their opinion about the treatment.

RESULTS

At 3 months there was a significant decrease in mean symptom score from 19.6 to 11.2 (P <0.0001). Mean peak flow rate increased from 8.5 to 12.8 mLs (P <0.0001). Mean postvoid residual urine decreased from 56.8 to 22.0 mL (P <0.0001). We did not observe any severe complications. Unlike prior studies, we removed the Foley catheter, and patients performed clean intermittent catheterization (CIC) when necessary. There was no significant differences in subjective and objective parameters between these patients and those who did not need CIC. Patient opinion about the treatment was not affected by CIC. About two thirds (67.2%) of the patients in the study group were satisfied with the results of treatment, and 60.3% would undergo the same procedure again.

CONCLUSIONS

TUMT of the prostate is an effective, safe, and acceptable form of treatment for patients with BPH. Longer follow-up is needed to examine the durability of TUMT treatment.