Ramsay L. Kuo

Randall’s plaque of patients with nephrolithiasis begins in basement membranes of thin loops of Henle

Our purpose here is to test the hypothesis that Randalls plaques, calcium phosphate deposits in kidneys of patients with calcium renal stones, arise in unique anatomical regions of the kidney, their formation conditioned by specific stone-forming pathophysiologies. To test this hypothesis, we performed intraoperative biopsies of plaques in kidneys of idiopathic-calcium-stone formers and patients with stones due to obesity-related bypass procedures and obtained papillary specimens from non-stone formers after nephrectomy. Plaque originates in the basement membranes of the thin loops of Henle and spreads from there through the interstitium to beneath the urothelium. Patients who have undergone bypass surgery do not produce such plaque but instead form intratubular hydroxyapatite crystals in collecting ducts. Non-stone formers also do not form plaque. Plaque is specific to certain kinds of stone-forming patients and is initiated specifically in thin-limb basement membranes by mechanisms that remain to be elucidated.

Major Complications in 213 Laparoscopic Nephrectomy Cases: The Indianapolis Experience

PURPOSE We assessed the incidence of and analyzed factors that may help prevent major complications and open conversion during laparoscopic nephrectomy at our institutions. MATERIALS AND METHODS We retrospectively analyzed all laparoscopic nephrectomies performed between August 1, 1999 and July 31, 2001. Data were stratified for nephrectomy type, intraoperative and postoperative complications. Conversion to open surgery was stratified for emergency versus elective procedures. RESULTS Of the 292 laparoscopic procedures performed at our institutions in 2 years 213 (73%) involved laparoscopic nephrectomy, including 84 live donor nephrectomies, 61 radical nephrectomies, 55 simple nephrectomies and 13 nephroureterectomies. A total of 16 major complications (7.5%) occurred, including access related, intraoperative and postoperative complications in 3, 9 and 4 cases, respectively. The conversion rate was 6.1% (13 patients), the transfusion rate was 1.9% and the mortality rate was 0.5% (1 death). Only 1 complication was related to simple laparoscopic nephrectomy, although this group showed the highest rate of elective conversion (7 of 8 elective conversions). Laparoscopic live donor nephrectomy showed the highest rate for emergency conversion (3 of 5 emergency conversions). CONCLUSIONS Our results reinforce the importance of thorough preoperative imaging, careful patient selection, surgeon experience and skill maintenance in laparoscopy as well as a low threshold for conversion to open surgery. This series provides additional evidence to support the evolution of laparoscopic nephrectomy into a standard of care.

Shockwave Lithotripsy: Anecdotes and Insights

Shockwave lithotripters have evolved considerably since the introduction of the Dornier HM3 machine 20 years ago. Although shockwave lithotripsy (SWL) remains the preferred treatment for the majority of symptomatic upper urinary-tract calculi, newer lithotripters are not as effective and may have a higher risk of side effects. Lack of progress in lithotripter evolution is attributable to inadequate understanding of how and why shockwaves produce effects on stone and tissue. Current knowledge suggests that stones fragment by the mechanisms of compression fracture, spallation, squeezing, and acoustic cavitation, while tissue damage from shockwaves is secondary to cavitation and non-cavitational forces such as sheer stress. It appears likely that most tissue damage from shockwaves is caused by cavitation. As the understanding of SWL matures, new lithotripter designs may emerge that truly represent an improvement on the original Dornier HM3 machine.

Holmium laser enucleation of the prostate for prostates of >125 mL

To examine a group of patients treated with holmium laser enucleation of the prostate (HoLEP) and with the bladder outlet obstructed by an exceptionally large (>125 mL) prostate, as such men are often not considered candidates for endoscopic treatments and historically have required open surgery.

Endoscopic Evidence of Calculus Attachment to Randall’s Plaque

PURPOSE It has been proposed that calcium oxalate calculi begin as small stones attached to the renal papillae at sites of Randalls plaque. However, no study has investigated the prevalence of attached stones in calcium oxalate stone formers or the relationship between stone attachment site and Randalls plaque. In this study we used endoscopic examination of renal papillae in stone formers undergoing percutaneous nephrolithotomy to investigate both issues. MATERIALS AND METHODS Idiopathic calcium oxalate stone formers undergoing PNL for stone removal were enrolled in this study. Multiple papillae were examined and images were recorded by digital video. The presence or absence of papillary plaque and attached stones was noted, as was the site of stone attachment. RESULTS In 23 patients, 24 kidneys and 172 renal papillae were examined. All kidneys were found to have papillary plaque and 11 of the patients had attached stones. Most papillae (91%) contained plaque. CONCLUSIONS The prevalence of attached stones in calcium oxalate stone formers (48%) is greater than that previously reported for the general population. Attachment appears to be on Randalls plaque. The high prevalence of attached stones and the appearance of the attachment site are consistent with a mechanism of calcium oxalate stone formation in which stones begin as plaque overgrowth.

Holmium Laser Enucleation of the Prostate (HoLEP): A Technical Update

IntroductionHolmium laser enucleation of the prostate (HoLEP) combined with mechanical morcellation represents the latest refinement of holmium:YAG surgical treatment for benign prostatic hyperplasia (BPH). Utilizing this technique, even the largest of glands can be effectively treated with minimal morbidity. The learning curve remains an obstacle, preventing more widespread adoption of this procedure. This paper provides an outline of the HoLEP technique as is currently used at two centers in hopes of easing the initial learning curve.Technical considerationsDetailed descriptions of the major steps of the HoLEP procedure are provided with attention to critical steps such as identification of the surgical capsule, median and lateral lobe enucleation, and morcellation of enucleated tissue.ConclusionsHoLEP is a promising alternative for the surgical treatment of BPH which allows complete removal of intact lobes of the prostate. Obstruction is relieved immediately with superior hemostasis, no risk of TUR syndrome, and a minimal hospital stay.

Laparoscopic treatment for ureteropelvic junction obstruction

OBJECTIVES To assess retrospectively the subjective and objective outcomes achieved after laparoscopic treatment for ureteropelvic junction obstruction at our institutions. METHODS Between August 1999 and July 2001, 19 patients (11 women and 8 men), with a mean age of 31.2 years (range 17 to 67), underwent laparoscopic treatment for ureteropelvic junction obstruction. Of these, 17 patients were eligible for postoperative analysis. Nine of these patients had a history of prior surgical intervention on the affected side. The patients were subjectively assessed by an analog pain scale performed before and at least 6 months after surgery. Preoperatively, patients had a diuretic renal scan to confirm the presence of obstruction. Helical computed tomography was also performed preoperatively to assess for the presence of crossing vessels. The renal scan was repeated at least 12 weeks after surgery to document the relief of obstruction objectively. RESULTS Helical computed tomography correctly predicted the presence of crossing vessels in 12 patients (63%). The Anderson-Hynes and Fenger pyeloplasty techniques were performed in 16 and 2 patients, respectively. In 1 patient, a small crossing vein over the ureteropelvic junction was identified and divided without complications. The average operative time was 240 minutes (range 128 to 470). The blood loss was minimal, and no open conversions were required. The mean hospital stay was 2.9 days (range 2 to 7). Two postoperative complications occurred (11.7%). The average subjective follow-up was 14.4 months (range 6 to 27), and the average objective follow-up was 7.8 months (range 3 to 12). Of 17 assessable patients, 16 (94%) had subjective and objective success (postoperative improvement in analog pain score and half-life of radiotracer washout). The average split renal function improved from 34.1% to 38.5% (P <0.01). CONCLUSIONS On the basis of our data, laparoscopic pyeloplasty has a similar success rate compared with the traditional open approach and better results than other minimally invasive techniques. Longer follow-up and further experience are needed to validate these data.

Topiramate-induced nephrolithiasis

Topiramate is a recently developed antiepileptic medication that is becoming more widely prescribed because of its efficacy in treating refractory seizures. Urologists should be aware that this medication can cause metabolic acidosis in patients secondary to inhibition of carbonic anhydrase. In addition, a distal tubular acidification defect may result, thus impairing the normal compensatory drop in urine pH. These factors can lead to the development of calcium phosphate nephrolithiasis. We report the first two cases of topiramate-induced nephrolithiasis in the urologic literature.

Holmium laser enucleation of the prostate: morbidity in a series of 206 patients

OBJECTIVES To review the complications associated with 206 holmium laser enucleation of the prostate (HoLEP) procedures. HoLEP is a minimally invasive surgical treatment for benign prostatic hyperplasia. METHODS A retrospective review was conducted of HoLEPs performed from April 1, 1999 to October 1, 2001. Patients with previous diagnoses of prostate carcinoma or who had undergone HoLEP after admission for unrelated problems were excluded. Demographic, intraoperative, and immediate postoperative data were recorded to determine the incidence of complications. Patients were also contacted by telephone or mailed surveys for documentation of longer term complications. RESULTS The mean age and procedure time was 70.5 years (range 45 to 91) and 133.6 minutes (range 25 to 473), respectively. The mean specimen weight was 68.2 g (range 3 to 376), with 20 (9.7%) of 206 patients diagnosed with adenocarcinoma. The mean hospital stay was 1.1 days, with 86.9% of patients discharged after an overnight stay without a catheter. Two patients required postoperative transfusions (1.0%). No deaths, major complications (myocardial infarction or pulmonary embolism), or transurethral resection syndrome episodes occurred. Intraoperative complications consisted of three capsular perforations (1.5%), one bladder neck false passage (0.5%), four incomplete morcellations (1.9%), and four minor bladder mucosal morcellation injuries (1.9%). Of 206 patients, 173 (84.0%) provided follow-up data (mean 19.0 +/- 8.4 months), allowing documentation of longer term complications, including five clot retention episodes (2.4%), five urethral strictures (2.4%), eight bladder neck contractures (3.9%), and 16 patients requiring re-catheterization (7.8%). CONCLUSIONS HoLEP can be performed with minimal complication risks and blood loss. Patients can expect an overnight hospital stay and discharge without an indwelling catheter.

Use of ureteroscopy and holmium:YAG laser in patients with bleeding diatheses

OBJECTIVES To assess the safety and efficacy of ureteroscopy and holmium laser in patients with known bleeding diatheses and upper tract calculi or transitional cell carcinoma (TCC). METHODS Eight patients with stone disease and 1 patient with upper tract TCC were treated ureteroscopically with the holmium laser. The mean age was 58.3 years (range 42 to 74). Six patients were receiving Coumadin, with a mean international normalized ratio (INR) of 2.1 (normal INR less than 1.1). Two patients were thrombocytopenic, and 1 had von Willebrands disease. None of the bleeding diatheses were corrected before surgery. Semirigid or flexible ureteroscopes were used to access the ureter or intrarenal collecting system. The holmium laser was used to fragment calculi or ablate tumor. RESULTS Only 1 patient had a postoperative bleeding complication related to the procedure, involving an episode of oliguria secondary to a small ureteral clot. This cleared without surgical intervention. Another patient developed an episode of epistaxis after administration of ketorolac for pain. Six of 7 patients who underwent laser fragmentation for calculi were stone free on follow-up intravenous urogram at 1 month, and no tumor recurrence was noted in the patient with TCC (follow-up of 4 months). CONCLUSIONS Ureteroscopy allowed excellent access to all regions of the upper tracts, and holmium laser fragmentation of calculi or ablation of tumor was effective in managing each particular problem. Use of the holmium laser with ureteroscopic access provides a safe and acceptable combination for treating upper tract pathology in patients with uncorrected bleeding diatheses. As a result, these patients can avoid added costs of extended hospital stay and risks associated with transfusions.