Ehud Gnessin

Shock wave lithotripsy: advances in technology and technique.

Shock wave lithotripsy (SWL) is the only noninvasive method for stone removal. Once considered as a primary option for the treatment of virtually all stones, SWL is now recognized to have important limitations that restrict its use. In particular, the effectiveness of SWL is severely limited by stone burden, and treatment with shock waves carries the risk of acute injury with the potential for long-term adverse effects. Research aiming to characterize the renal response to shock waves and to determine the mechanisms of shock wave action in stone breakage and renal injury has begun to suggest new treatment strategies to improve success rates and safety. Urologists can achieve better outcomes by treating at slower shock wave rate using a step-wise protocol. The aim is to achieve stone comminution using as few shock waves and at as low a power level as possible. Important challenges remain, including the need to improve acoustic coupling, enhance stone targeting, better determine when stone breakage is complete, and minimize the occurrence of residual stone fragments. New technologies have begun to address many of these issues, and hold considerable promise for the future.

Holmium laser enucleation of the prostate: efficiency gained by experience and operative technique.

PURPOSE Holmium laser enucleation of the prostate is highly effective for symptomatic benign prostatic hyperplasia. Despite its steep learning curve the procedure is an efficient treatment, especially for large prostate glands. We determined the change in enucleation efficiency with time with increased operative experience and improved technique. MATERIALS AND METHODS We reviewed the records of all 949 consecutive men who underwent holmium laser enucleation of the prostate between 1999 and 2007. Patients were excluded from analysis when enucleated gm or time was not recorded and enucleated tissue was less than 5 gm. Efficiency was measured in gm enucleated prostate tissue per minute. Descriptive statistics on laser time, gland weight and efficiency were evaluated in an 8-year period. RESULTS A total of 91 patients met study exclusion criteria, leaving 858 available for evaluation. Mean enucleation time was 94 minutes (range 12 to 485). Mean prostate specimen weight was 77 gm (range 5 to 376). Mean efficiency or enucleation rate was 0.55 vs 1.32 gm per minute in the first 4 vs the last 5 years. Further efficiency improvements were noted in the last 5 years with a mean of 1.57 gm per minute enucleated in the last 2 years. CONCLUSIONS As experience with holmium laser enucleation of the prostate grows, advances in operative technique have been made. Prostatic enucleation efficiency continues to improve, further strengthening the role of holmium laser enucleation of the prostate for benign prostatic hyperplasia of small and large prostate glands.

Management of urogenital trauma: state of the art.

Purpose of review The field of urogenital trauma is undergoing constant improvement mainly due to better diagnostic tools, a shift toward standardized treatments and better trauma care. The purpose of this review is to summarize the most relevant studies published within the last 3 years on the subject. Recent findings Computerized tomography grading of renal trauma is an excellent predictor of the need for surgery and the final renal outcome in these patients, as most patients can be treated conservatively. Computerized tomography cystography has become the standard for the diagnosis of bladder rupture in which the indications for surgical intervention may be changing. The most common urethral trauma is posterior urethral injury due to pelvic fracture. The best results in adults and children are achieved by urethroplasty. Summary The diagnosis and treatment of genitourinary trauma is still evolving. The long-term sequels of these injuries may best be treated by urologists expert in urogenital reconstruction. In the future, tissue engineering may have an important place in the treatment of these patients.

Changing composition of renal calculi in patients with musculoskeletal anomalies.

BACKGROUND AND PURPOSE Calculi from patients with musculoskeletal (MS) anomalies who are largely immobile and prone to urinary infections have been traditionally composed primarily of struvite and carbonate apatite. Because of substantial improvements in the care of these patients in recent decades, stone etiology may have shifted from infectious to metabolic. We assessed the composition of renal calculi and metabolic characteristics in a contemporary cohort of patients with MS anomalies who underwent percutaneous nephrolithotomy (PCNL). PATIENTS AND METHODS Retrospective analysis of patients who underwent PCNL between April 1999 and June 2009 and had follow-up 24-hour urine studies was performed. Patients with MS anomalies included spinal cord injury, myelomeningocele, muscular dystrophy, multiple sclerosis, cerebral palsy, or other clinical syndromes causing kyphoscoliosis and contractures. RESULTS Our cohort included 33 patients with MS anomalies and 334 consecutive patients as a control group who underwent PCNL and had metabolic workup. Stones were infectious in etiology in 18.4% and 6.2% in MS and control groups, respectively. Thus, most patients harbored stones of metabolic origin. Metabolic stones in the MS group were composed of 52.7% hydroxyapatite, 10.5% calcium oxalate, 7.9% brushite, 2.6% uric acid, 0% cystine, and 7.9% other. Metabolic stones in the control group were 50.5% calcium oxalate, 16.4% hydroxyapatite, 11.5% brushite, 10.8% uric acid, 4.3% cystine, and 0.3% other. Mean 24-hour urine values for patients with metabolic stones in MS/control groups were volume 2.18/1.87 L/d, pH 6.78/6.05, calcium to creatinine ratio 220/151 mg/g, and oxalate 44.8/39.5 mg/d. CONCLUSIONS Although patients with MS anomalies are traditionally thought to harbor infection-related calculi, most will be found to have calculi of metabolic etiology. The incidence of calcium phosphate stones is high in this group of patients, perhaps reflecting their high urinary pH.

The Utility of Noncontrast Computed Tomography in the Prompt Diagnosis of Postoperative Complications After Percutaneous Nephrolithotomy

INTRODUCTION Noncontrast computed tomography (CT) is commonly utilized after percutaneous nephrolithotomy (PNL) to assess stone-free (SF) status. In addition to assessing SF status, CT is useful in the recognition of complications after PNL. We characterized complications demonstrated by postoperative CT scan and compared hospital re-admission rates based on whether or not CT was performed. METHODS We retrospectively reviewed records of 1032 consecutive patients from April 1999 to June 2010. Patients were divided into two cohorts based on whether they had a CT within 24 hours of PNL. Demographic data, CT findings, and need for re-admission for complication management were assessed. RESULTS Nine hundred fifty-seven patients (92.7%) underwent post-PNL CT. CT-diagnosed complications were perinephric hematoma in 41 (4.3%; 2 requiring embolization and 9 necessitating transfusion), pleural effusion in 25 (2.6%; 10 requiring intervention), colon perforation in 2 (0.2%), and splenic injury in 2 (0.2%). Of patients with postoperative complications, 33% required intervention. Among patients with a CT, 6 (0.6%) were readmitted despite negative postoperative CT (four perinephric hematomas, one calyceal-pleural fistula, and one pseudoaneurysm). The sensitivity of CT for diagnosing complications was 92.7%. Seventy-five patients (7.3%) did not undergo CT post-PNL. Of these, four (5.33%) were readmitted: three for perinephric hematomas and one for ureteral clot obstruction. Patients undergoing post-PNL CT were less likely to be readmitted because of missed complications (p=0.02). CONCLUSIONS Serious post-PNL complications are uncommon, but their prompt diagnosis and treatment is imperative. In addition to identifying residual stones, CT is useful in diagnosing postoperative complications. Postoperative CT could potentially be considered for all patients undergoing PNL, particularly in complex cases such as patients with anatomical abnormalities (renal anatomic abnormality or retrorenal colon), patients requiring upper pole access (risk of thoracic, hepatic, and splenic complications), and patients requiring multisite access (higher risk of perinephric hematoma or need for transfusion).

Preoperative Bladder Urine Culture as a Predictor of Intraoperative Stone Culture Results: Clinical Implications and Relationship to Stone Composition

PURPOSE We examine the relationship between urine and stone cultures in a large cohort of patients undergoing percutaneous stone removal and compare the findings in infectious vs metabolic calculi. MATERIALS AND METHODS A total of 776 patients treated with percutaneous nephrolithotomy who had preoperative urine cultures and intraoperative stone cultures were included in the study. Statistical analysis used chi-square or logistic fit analysis as appropriate. RESULTS Preoperative urine culture was positive in 352 patients (45.4%) and stone cultures were positive in 300 patients (38.7%). There were 75 patients (9.7%) with negative preoperative cultures who had positive stone cultures, and in patients with both cultures positive the organisms differed in 103 (13.3%). Gram-positive organisms predominated in preoperative urine and stone cultures. CONCLUSIONS Preoperative urine cultures in patients undergoing percutaneous nephrolithotomy are unreliable as there is a discordance with intraoperative stone cultures in almost a quarter of cases. There has been a notable shift toward gram-positive organisms in this cohort of patients.

Imaging Evaluation in the Patient With Renal Stone Disease

Numerous imaging modalities are available for the evaluation of patients with renal stone disease. The study of choice is dependent on the clinical scenario and the indication for imaging. Additional factors such as patient age and pregnancy status will influence the radiographic study that is chosen. Currently available technologies for the evaluation of urolithiasis include plain abdominal radiography, ultrasound, intravenous pyelogram, computed tomography, and magnetic resonance imaging. This article reviews the indications, advantages, and disadvantages of each study in the evaluation of patients with known or suspected stone disease.

An update on holmium laser enucleation of the prostate and why it has stood the test of time

Purpose of review Holmium laser enucleation of the prostate is an endoscopic alternative for the treatment of symptomatic benign prostatic hyperplasia for men with prostates of any size. Holmium laser enucleation of the prostate is superior to other modalities for the treatment of benign prostatic hyperplasia. We present the most current literature on this procedure. Recent findings In the 18-month span of this review, there have been a number of articles published on holmium laser enucleation of the prostate. These studies assessed the safety, efficacy, and durability of this procedure. Among these is the largest study to date providing supporting evidence to the long-term efficacy and safety of holmium laser enucleation of the prostate. Other studies provide compelling evidence to suggest that holmium laser enucleation of the prostate can be used in prostates of any size and can provide long-term durable outcomes. Summary Holmium laser enucleation of the prostate represents an effective, well tolerated, and durable procedure to relieve bladder outlet obstruction due to benign prostatic hyperplasia. Holmium laser enucleation of the prostate is a minimally invasive approach which accomplishes complete adenoma removal and, as such, provides unique advantages over other surgical treatments for men with benign prostatic hyperplasia.

Current Understanding of the Role of Randall’s Plaque

The mechanisms by which urinary calculi develop in humans are not entirely understood. In the 1930s, Randall described white plaques on the papillae of cadaveric kidneys from patients with calculi and postulated that this was the site of stone formation in all stone formers. His theory was not well received and for many years was abandoned. It is now known that in certain subsets of stone formers (idiopathic calcium oxalate stone formers), stone formation does occur by overgrowth on Randall’s plaque. However, many other types of stone formers do not demonstrate evidence of classic Randall’s plaque and must therefore possess a different mechanism for stone formation. Careful endoscopic assessment and renal tissue biopsies from unique stone-forming patients (i.e., those with cystinuria, primary hyperparathyroidism, renal tubular acidosis, and primary hyperoxaluria) has revealed evidence of crystalline plugging within dilated ducts of Bellini with associated inflammation and cell injury. These findings are not identified in idiopathic calcium oxalate stone formers and lead one to believe that alternate pathways to the development of nephrolithiasis must be at play. In this chapter we review the composition and anatomic location of Randall’s plaque as well as describe the stone-plaque interface and mechanism of stone overgrowth. Additionally, we review the specific endoscopic and histologic abnormalities in stone-forming patients with cystinuria, brushite stone disease, gastric bypass, ileostomy, primary hyperparathyroidism, renal tubular acidosis, and primary hyperoxaluria and propose potential mechanisms for stone formation.

Percutaneous Management of Calyceal Diverticula: An American Experience

Calyceal diverticula are congenital, non-secretory, urothelium-lined cavities within the kidney. They communicate with the collecting system via narrow infundibula and fill retrogradely with urine. Some diverticuli remain asymptomatic over time, while others cause flank pain, hematuria, and recurrent urinary tract infections or develop calculi. While asymptomatic diverticula can be managed conservatively, symptomatic or stone-containing diverticula should be treated. Due to the development of minimally invasive methods for the treatment of symptomatic diverticula, open surgical techniques such as unroofing, marsupialization, and open diverticulectomy have become obsolete. Currently available minimally invasive techniques for treating calyceal diverticula include extracorporeal shock wave lithotripsy (ESWL), ureteroscopy, laparoscopy, and percutaneous nephrolithotomy (PNL). ESWL does not lead to adequate stone-free rates and does not allow for simultaneous ablation of the diverticular cavity. Ureteroscopy is an acceptable form of treatment for upper or mid pole diverticula and involves incision or balloon dilation of the diverticular neck followed by stone removal and obliteration of the diverticular cavity, if possible. This technique is difficult to perform in lower pole lesions due to the limited flexion capabilities of flexible ureteroscopes, and may not be possible in the case of diverticula with very small ostia. Laparoscopy is generally reserved for anteriorly located diverticula with minimal surrounding parenchyma. This technique is successful in experienced hands, but operative times are often substantially longer than with other modalities. PNL provides the highest stone-free, symptom resolution, and diverticular resolution rates but can pose a significant challenge to urologists owing to the small working space within the diverticular cavity and the difficulty associated with safely maintaining wire access. Additionally, the majority of diverticula are located in the upper pole, and pleural complications such as hydro- or hemothorax associated with supracostal, upper pole access are of significant concern. Here we describe a single stage, infracostal approach for the percutaneous management of symptomatic calyceal diverticula.