Screening for asymptomatic nephrolithiasis in primary hyperparathyroidism patients is warranted

BACKGROUND

We aimed to investigate the prevalence, characteristics, and management of nephrolithiasis in primary hyperparathyroidism (PHPT) patients.

METHODS

Medical records of patients who underwent parathyroidectomy at a tertiary care hospital in British Columbia from January 2016 to April 2023 were retrospectively reviewed. Demographic data, laboratory results, imaging reports, and urologic consultations were examined. Descriptive statistics and relevant statistical tests, including logistic regressions, were utilized for data analysis.

RESULT

Of the 413 PHPT patients included in the study population, 41.9% harbored renal stones, and nearly half (48.6%) required urological interventions. Male sex, elevated preoperative serum ionized calcium (iCa) and 24-h urinary calcium (24 ​h urine Ca) levels were independent risk factors for stone formation. Additionally, male sex, younger age, and lower preoperative serum 25-hydroxyvitamin D (25(OH)D) level were associated with higher odds of requiring urological intervention for stones.

CONCLUSIONS

This study identified significant prevalence of asymptomatic renal calcifications in PHPT patients, with a substantial proportion necessitating urological intervention. These findings emphasize the importance of incorporating screening and treatment of renal stones into the management of PHPT patients.

Mechanisms of Pulse Modulated Holmium:YAG Lithotripsy

Introduction: This study aimed at answering three research questions: (1) Under the experimental conditions studied, what is the dominant mechanism of Holmium:YAG lithotripsy with or without pulse modulation? (2) Under what circumstances can laser pulse modulation increase crater volume of stone ablation per joule of emitted radiant energy? (3) Are BegoStone phantoms a suitable model for laser lithotripsy studies? Materials and Methods: The research questions were addressed by ablation experiments with BegoStone phantoms and native stones. Experiments were performed under three stone conditions: dry stones in air, hydrated stones in air, and hydrated stones in water. Single pulses with and without pulse modulation were applied. For each pulse mode, temporal profile, transmission through 1 mm water, and cavitation bubble collapse pressures were measured and compared. For each stone condition and pulse mode, stones were ablated with a fiber separation distance of 1 mm and crater volumes were measured using optical coherence tomography. Results: Pulses with and without pulse modulation had high (>80%) transmission through 1 mm of water. Pulses without pulse modulation generated much higher peak pressures than those with pulse modulation (62.3 vs 11.4 bar). Pulse modulation resulted in similar or larger craters than without pulse modulation. Trends in BegoStone crater volumes differed from trends in native stones. Conclusions: This results of this study suggest that the dominant mechanism is photothermal with possible photoacoustic contributions for some stone compositions. Pulse modulation can increase ablation volume per joule of emitted radiant energy, but the effect may be composition specific. BegoStones showed unique infrared ablation characteristics compared with native stones and are not a suitable model for laser lithotripsy studies.

Does early intervention improve outcomes for patients with acute ureteral colic?

OBJECTIVES

Early surgical intervention is increasingly employed for patients with ureteral colic, but guidelines and current practice are variable. We compared 60-day outcomes for matched patients undergoing early intervention vs. spontaneous passage.

METHODS

This multicentre propensity-matched cohort analysis used administrative data and chart review to study all eligible emergency department (ED) patients with confirmed 2.0-9.9 mm ureteral stones. Those having planned stone intervention within 5 days comprised the intervention cohort. Controls attempting spontaneous passage were matched to intervention patients based on age, sex, stone width, stone location, hydronephrosis, ED site, ambulance arrival and acuity level. The primary outcome was treatment failure, defined as rescue intervention or hospitalization within 60 days, using a time to event analysis. Secondary outcome was ED revisit rate.

RESULTS

Among 1154 matched patients, early intervention did not reduce the risk of treatment failure (adjusted hazard ratio 0.94; P = 0.61). By 60 days, 21.8% of patients in both groups experienced the composite primary outcome (difference 0.0%; 95% confidence interval - 4.8 to 4.8%). Intervention patients required more hospitalizations (20.1% vs. 12.8%; difference 7.3%; 95% CI 3.0-11.5%) and ED revisits (36.1% vs. 25.5%; difference 10.6%; 95% CI 5.3-15.9%), but (insignificantly) fewer rescue interventions (18.9% vs. 21.3%; difference - 2.4%; 95% CI - 7.0 to 2.2%).

CONCLUSIONS

In matched patients with 2.0-9.9 mm ureteral stones, early intervention was associated with similar rates of treatment failure but greater patient morbidity, evidenced by hospitalizations and emergency revisits. Physicians should adopt a selective approach to interventional referral and consider that spontaneous passage probably provides better outcomes for many low-risk patients.

Hydronephrosis severity clarifies prognosis and guides management for emergency department patients with acute ureteral colic

OBJECTIVE

In emergency department patients with ureteral colic, the prognostic value of hydronephrosis is unclear. Our goal was to determine whether hydronephrosis can differentiate low-risk patients appropriate for trial of spontaneous passage from those with clinically important stones likely to experience passage failure.

METHODS

We used administrative data and structured chart review to evaluate a consecutive cohort of patients with ureteral stones who had a CT at nine Canadian hospitals in two cities. We used CT, the gold standard for stone imaging, to assess hydronephrosis and stone size. We described classification accuracy of hydronephrosis severity for detecting large (≥ 5 mm) stones. In patients attempting spontaneous passage we used hierarchical Bayesian regression to determine the association of hydronephrosis with passage failure, defined by the need for rescue intervention within 60 days. To illustrate prognostic utility, we reported pre-test probability of passage failure among all eligible patients (without hydronephrosis guidance) to post-test probability of passage failure in each hydronephrosis group.

RESULTS

Of 3251 patients, 70% male and mean age 51, 38% had a large stone, including 23%, 29%, 53% and 72% with absent, mild, moderate and severe hydronephrosis. Passage failure rates were 15%, 20%, 28% and 43% in the respective hydronephrosis categories, and 23% overall. "Absent or mild" hydronephrosis identified a large subset of patients (64%) with low passage failure rates. Moderate hydronephrosis predicted slightly higher, and severe hydronephrosis substantially higher passage failure risk.

CONCLUSIONS

Absent and mild hydronephrosis identify low-risk patients unlikely to experience passage failure, who may be appropriate for trial of spontaneous passage without CT imaging. Moderate hydronephrosis is weakly associated with larger stones but not with significantly greater passage failure. Severe hydronephrosis is an important finding that warrants definitive imaging and referral. Differentiating "moderate-severe" from "absent-mild" hydronephrosis provides risk stratification value. More granular hydronephrosis grading is not prognostically helpful.

Pulse modulation with Moses technology improves popcorn laser lithotripsy

PURPOSE

Moses™ technology has been developed to improve holmium laser fragmentation at 1-2 mm distance from the stone. Because popcorn lithotripsy is a non-contact technique, we compared short pulse (SP) and Moses distance (MD) modes in an in vitro model.

METHODS

BegoStones were fragmented using a 120 W Ho:YAG laser (P120 Moses) and a 230 μm core fiber introduced through a ureteroscope. 20 W (1 J × 20 Hz; 0.5 J × 40 Hz) and 40 W (1 J × 40 Hz; 0.5 J × 80 Hz) settings (total energy 4.8 kJ) were tested using SP and MD modes. We assessed fragment size distribution and mass lost in fluid (initial mass-final dry mass of all sievable fragments). High-speed video analysis of fragmentation strike rate and vapor bubble characteristics was conducted for 1 J × 20 Hz and 0.5 J × 80 Hz. Laser strike rate (number of strikes divided by frequency) was categorized as: (1) direct-a visual plume of dust ejected from stone while in contact with fiber tip; (2) indirect-a visual plume of dust ejected with distance between stone and fiber tip.

RESULTS

For 1 J × 20 Hz (20 W), MD resulted in more mass lost in fluid and a lower distribution of fragments ≥ 2 mm compared to SP (p < 0.05). 0.5 J × 80 Hz (40 W) produced no fragments ≥ 2 mm, and there were no significant differences in fragment distribution between MD and SP (p = 0.34). When using MD at 1 J × 20 Hz, 96% of strikes were indirect vs 61% for SP (p = 0.059). In contrast to the single bubble of SP, with MD, there was forward movement of the collapsing second bubble, away from the fiber-tip.

CONCLUSIONS

For lower frequency and power popcorn settings, pulse modulation results in more fragmentation through true non-contact laser lithotripsy.

Understanding the Popcorn Effect During Holmium Laser Lithotripsy for Dusting

OBJECTIVE

To assess low and high power settings for the popcorn technique, and relationship of laser fiber-to-stone distance and calyceal size on submillimeter fragmentation. Our in vitro findings may help guide strategies to improve a dusting technique for ureteroscopy.

METHODS

BegoStones were fragmented in small (127 mm³) and large (411 mm³) sized bulbs to simulate calyces, using a 120 W Ho:YAG laser. A 242 μm fiber was introduced through a ureteroscope mounted to a 3D positioner with its tip located at 0 or 2 mm distance from the stones. 20 W [1 J × 20 Hz, 0.5 J × 40 Hz] and 40 W [1 J × 40 Hz, 0.5 J × 80 Hz] settings were assessed, including short pulse and long pulse modes. Total energy delivered was constant at 7.2 kJ. Primary outcome was percentage of stone mass converted to fragments <1 mm. High-speed imaging was performed to study stone movement and/or fragmentation.

RESULTS

For all settings, popcorn lithotripsy yielded more submillimeter fragments when performed with the fiber positioned on the stone compared to 2 mm from the stone (P <.05). Distribution of submillimeter fragments was higher when utilizing high frequencies regardless of pulse energy. At 2 mm distance, popcorning was more effective in the small model (P <.05). At 2 mm distance, short pulse was superior to long pulse. Video analysis showed fragmentation did not occur when stones collided with each other. At 80 Hz/2 mm distance, only 17.5% of pulses impacted fragments.

CONCLUSION

Popcorn technique is more effective when the fiber is directly in contact with stone, and when performed in a small calyceal model. Utilizing settings with higher frequencies may improve dusting outcomes.

Comparison of flexible ureteroscopy damage rates for lower pole renal stones by laser fiber type

OBJECTIVES

Laser lithotripsy, often used during ureteronephroscopy (URNS), requires the Ho:YAG optical fiber transmit energy via total internal reflection (TIR). In critical lower pole deflections, energy may refract into the cladding causing fiber failure and scope damage. New optical fiber technology aims to have increased tolerance for high degrees of flexion. We compared two brands of laser fibers with sub-300 micron cores (Sureflex, Boston Flexiva) to determine failure rates and scope repair costs.

METHODS

A retrospective cohort study comparing these two fibers for patients at a single academic institution who underwent flexible URNS with laser lithotripsy was performed from September 2013 to October 2015. Preoperative imaging was evaluated for stone burden and location. Intraoperative variables were collected, including energy use, lower pole lasering, laser fiber malfunction, and scope damage. The primary outcome was scope damage caused by laser fiber malfunction. Secondary outcome was scope repair costs. Fisher's exact test and two tailed t-tests were used.

RESULTS

Of 223 subjects, 143 met inclusion criteria, and 8 had laser fiber failure. All failures occurred with the Sureflex fiber (8 of 63, 13%) vs the Boston Flexiva fiber (0 of 80, 0%) (P < 0.01). Malfunctions occurred in 8 of 79 lower pole stone applications versus 0 of 64 non-lower pole stone laser applications (P < 0.01). No other risk factor was different between fiber cohorts, except energy setting. Scope repair cost averaged $9155 CDN, yielding an average repair cost per case of $1144 CDN for the Sureflex versus $0 for the Boston fiber (P < 0.01).

CONCLUSIONS

Both optical fibers perform well in non-lower pole locations. However, the challenge for laser fibers in lower pole URNS is to maintain TIR. Fiber failure reflects an inability to maintain reflection and is not based on energy used or stone burden. The Boston Flexiva laser fiber has fewer failures, resulting in $0 repair cost per case, compared to the Sureflex fiber in URNS with an average repair cost of $1144 CDN per case. Lasers Surg. Med. 50:798-801, 2018. © 2018 Wiley Periodicals, Inc.

Noninfectious Penile Lesions

Noninfectious penile lesions are classified by clinical presentation as papulosquamous (e.g., psoriasis), inflammatory (e.g., lichen sclerosus, lichen nitidus, lichen planus), vascular (e.g., angiokeratomas), or neoplastic (e.g., carcinoma in situ, invasive squamous cell carcinoma). Psoriasis presents as red or salmon-colored plaques with overlying silvery scales, often with extragenital cutaneous lesions. Lichen sclerosus presents as a phimotic, hypopigmented prepuce or glans penis with a cellophane-like texture. Lichen nitidus usually produces asymptomatic pinhead-sized, hypopigmented papules. The lesions of lichen planus are pruritic, violaceous, polygonal papules that are typically systemic. Angiokeratomas are typically asymptomatic, well-circumscribed, red or blue papules, often with annular or figurate configurations. Carcinoma in situ should be suspected if there are velvety red or keratotic plaques on the glans penis or prepuce, whereas invasive squamous cell carcinoma presents as a painless lump, ulcer, or fungating mass. Some benign lesions, such as psoriasis and lichen planus, may mimic carcinoma in situ or invasive squamous cell carcinoma. Biopsy is indicated if the diagnosis is in doubt or neoplasm cannot be excluded. The management of benign noninfectious penile lesions usually involves observation, topical corticosteroids, or topical calcineurin inhibitors. Neoplastic lesions generally warrant organ-sparing surgery.

Common Questions About Chronic Prostatitis

Chronic prostatitis is relatively common, with a lifetime prevalence of 1.8% to 8.2%. Risk factors include conditions that facilitate introduction of bacteria into the urethra and prostate (which also predispose the patient to urinary tract infections) and conditions that can lead to chronic neuropathic pain. Chronic prostatitis must be differentiated from other causes of chronic pelvic pain, such as interstitial cystitis/bladder pain syndrome and pelvic floor dysfunction; prostate and bladder cancers; benign prostatic hyperplasia; urolithiasis; and other causes of dysuria, urinary frequency, and nocturia. The National Institutes of Health divides prostatitis into four syndromes: acute bacterial prostatitis, chronic bacterial prostatitis (CBP), chronic nonbacterial prostatitis (CNP)/chronic pelvic pain syndrome (CPPS), and asymptomatic inflammatory prostatitis. CBP and CNP/CPPS both lead to pelvic pain and lower urinary tract symptoms. CBP presents as recurrent urinary tract infections with the same organism identified on repeated cultures; it responds to a prolonged course of an antibiotic that adequately penetrates the prostate, if the urine culture suggests sensitivity. If four to six weeks of antibiotic therapy is effective but symptoms recur, another course may be prescribed, perhaps in combination with alpha blockers or nonopioid analgesics. CNP/CPPS, accounting for more than 90% of chronic prostatitis cases, presents as prostatic pain lasting at least three months without consistent culture results. Weak evidence supports the use of alpha blockers, pain medications, and a four- to six-week course of antibiotics for the treatment of CNP/CPPS. Patients may also be referred to a psychologist experienced in managing chronic pain. Experts on this condition recommend a combination of treatments tailored to the patient's phenotypic presentation. Urology referral should be considered when appropriate treatment is ineffective. Additional treatments include pelvic floor physical therapy, phytotherapy, and pain management techniques. The UPOINT (urinary, psychosocial, organ-specific, infection, neurologic/systemic, tenderness) approach summarizes the various factors that may contribute to presentation and can guide treatment.

A multicenter comparison of the safety and effectiveness of ureteroscopic laser lithotripsy in obese and normal weight patients

OBJECTIVE

Surgical treatment of kidney stones in an obese patient (body mass index [BMI] >30 kg/m(2)) remains challenging as shockwave lithotripsy may not be an option due to weight limitations. We sought to determine the effectiveness of ureteroscopic laser lithotripsy in obese patients compared to nonobese controls.

MATERIALS AND METHODS

Patients from 2004 to 2007 were retrospectively analyzed providing a group of 292 patients (163 obese, 76 overweight, 53 normal) who underwent ureteroscopic procedures for urolithiasis at four centers in the United States and Canada.

RESULTS

The percentage of obese patients requiring flexible ureteroscopy (URS) (79%) was higher than in the other groups (P<0.0001). Flexible URS was associated with a lower stone-free rate (SFR) on multivariate analysis (P=0.034). There was no difference in SFRs of patients who required a ureteral access sheath, basket extraction, or received a postoperative stent. Complication rates did not differ between groups.

CONCLUSION

SFRs using ureteroscopic lithotripsy in obese and overweight populations are the same as in the normal weight patients. A flexible ureteroscope was associated with a decreased SFR, but this likely due to a more proximal stone location in these patients. Ureteroscopic laser lithotripsy is an effective and safe technique to treat urolithiasis in the overweight/obese patient.

Evaluation of a new 240-μm single-use holmium:YAG optical fiber for flexible ureteroscopy

BACKGROUND AND PURPOSE

Numerous holmium:yttrium-aluminum-garnet laser fibers are available for flexible ureteroscopy. Performance and durability of fibers can vary widely among different manufacturers and their product lines with differences within a single product line have been reported. We sought to evaluate a newly developed nontapered, single-use 240-μm fiber, Flexiva™ 200 (Boston Scientific, Natick, MA), during clinical use and in a bench-testing model.

MATERIALS AND METHODS

A total of 100 new fibers were tested after their use in 100 consecutive flexible ureteroscopic lithotripsy procedures by a single surgeon (B.K.). Prospectively recorded clinical parameters were laser pulse energy and frequency settings, total energy delivered and fibers failure. Subsequently, each fiber was bench-tested using an established protocol. Parameters evaluated for were fibers true diameter, flexibility, tip degradation, energy transmission in straight and 180° bend configuration and fibers failure threshold with stress testing.

RESULTS

The mean total energy delivered was 2.20 kJ (range 0-18.24 kJ) and most common laser settings used were 0.8 J at 8 Hz, 0.2 J at 50 Hz, and 1.0 J at 10 Hz, respectively. No fiber fractured during clinical procedures. The true fiber diameter was 450 μm. Fiber tips burnt back an average of 1.664 mm, but were highly variable. With laser setting of 400 mJ at 5 Hz, the mean energy transmitted was 451 and 441 mJ in straight and 180° bend configuration, respectively. Thirteen percent of fibers fractured at the bend radius of 0.5 cm with a positive correlation to the total energy transmitted during clinical use identified.

CONCLUSION

Fiber performance was consistent in terms of energy transmission and resistance to fracture when activated in bent configuration. Fiber failure during stress testing showed significant correlation with the total energy delivered during the clinical procedure. The lack of fiber fracture during clinical use may reduce the risk of flexible endoscope damage due to fiber failure.

Ureteroscopic ultrasound technology to size kidney stone fragments: proof of principle using a miniaturized probe in a porcine model

PURPOSE

A prototype ultrasound-based probe for use in ureteroscopy was used for in vitro measurements of stone fragments in a porcine kidney.

METHODS

Fifteen human stones consisting of three different compositions were placed deep in the collecting system of a porcine kidney. A 2 MHz, 1.2 mm (3.6F) needle hydrophone was used to send and receive ultrasound pulses for stone sizing. Calculated stone thicknesses were compared with caliper measurements.

RESULTS

Correlation between ultrasound-determined thickness and caliper measurements was excellent in all three stone types (r(2) = 0.90, p < 0.0001). All 15 ultrasound measurements were accurate to within 1 mm, and 10 measurements were accurate within 0.5 mm.

CONCLUSION

A 3.6F ultrasound probe can be used to accurately size stone fragments to within 1 mm in a porcine kidney.

The relationship between sexual abuse and interstitial cystitis/painful bladder syndrome

Interstitial cystitis/painful bladder syndrome (IC/PBS) is a chronic syndrome characterized by irritative voiding symptoms and pelvic pain or discomfort. IC/PBS represents localized bladder pathophysiologic changes and central nervous system upregulation. Patients exhibit bladder hyperalgesia and allodynia. Childhood sexual abuse occurs in up to 27% of females in the United States. Adults with a prior history of abuse or traumatization demonstrate hypothalamic-pituitary-adrenal (HPA) axis abnormalities, similar to IC/PBS patients. Childhood sexual abuse and physical traumatization are associated with subsequent lifelong risks of chronic pain syndromes. IC/PBS patients have increased rates of sexual abuse or physical traumatization histories compared with controls. IC/PBS patients with abuse histories tend to have greater pain intensity and lesser irritative voiding symptoms compared with nonabused IC/PBS patients. This article reviews the relationship between sexual abuse, HPA axis abnormalities, IC/PBS pathophysiology, and the role of sexual abuse on subsequent IC/PBS.

Femtosecond laser lithotripsy: feasibility and ablation mechanism

Light emitted from a femtosecond laser is capable of plasma-induced ablation of various materials. We tested the feasibility of utilizing femtosecond-pulsed laser radiation (lambda=800 nm, 140 fs, 0.9 mJ/pulse) for ablation of urinary calculi. Ablation craters were observed in human calculi of greater than 90% calcium oxalate monohydrate (COM), cystine (CYST), or magnesium ammonium phosphate hexahydrate (MAPH). Largest crater volumes were achieved on CYST stones, among the most difficult stones to fragment using Holmium:YAG (Ho:YAG) lithotripsy. Diameter of debris was characterized using optical microscopy and found to be less than 20 microm, substantially smaller than that produced by long-pulsed Ho:YAG ablation. Stone retropulsion, monitored by a high-speed camera system with a spatial resolution of 15 microm, was negligible for stones with mass as small as 0.06 g. Peak shock wave pressures were less than 2 bars, measured by a polyvinylidene fluoride (PVDF) needle hydrophone. Ablation dynamics were visualized and characterized with pump-probe imaging and fast flash photography and correlated to shock wave pressures. Because femtosecond-pulsed laser ablates urinary calculi of soft and hard compositions, with micron-sized debris, negligible stone retropulsion, and small shock wave pressures, we conclude that the approach is a promising candidate technique for lithotripsy.

Noninfectious penile lesions

Family physicians commonly diagnose and manage penile cutaneous lesions. Noninfectious lesions may be classified as inflammatory and papulosquamous (e.g., psoriasis, lichen sclerosus, angiokeratomas, lichen nitidus, lichen planus), or as neoplastic (e.g., carcinoma in situ, invasive squamous cell carcinoma). The clinical presentation and appearance of the lesions guide the diagnosis. Psoriasis presents as red or salmon-colored plaques with overlying scales, often with systemic lesions. Lichen sclerosus presents as a phimotic, hypopigmented prepuce or glans penis with a cellophane-like texture. Angiokeratomas are typically asymptomatic, well-circumscribed, red or blue papules, whereas lichen nitidus usually produces asymptomatic pinhead-sized, hypopigmented papules. The lesions of lichen planus are pruritic, violaceous, polygonal papules that are typically systemic. Carcinoma in situ should be suspected if the patient has velvety red or keratotic plaques of the glans penis or prepuce, whereas invasive squamous cell carcinoma presents as a painless lump, ulcer, or fungating irregular mass. Some benign lesions, such as psoriasis and lichen planus, can mimic carcinoma in situ or squamous cell carcinoma. Biopsy is indicated if the diagnosis is in doubt or neoplasm cannot be excluded. The management of benign penile lesions usually involves observation or topical corticosteroids; however, neoplastic lesions generally require surgery.

Quantification of holmium:yttrium aluminum garnet optical tip degradation

INTRODUCTION

Optical laser fibers are utilized to transmit energy to the surface of a stone during holmium:yttrium aluminum garnet (Ho:YAG) laser lithotripsy. During lithotripsy, fiber tip degradation (burn back) can occur. Fiber burn back may diminish fragmentation efficiency, increase operative time, and increase cost because of fiber replacement. We hypothesize that fiber tip degradation (burn back) varies among different commercially available Ho:YAG laser fibers.

METHODS

Fibers of varying core diameter sizes for Ho:YAG lithotripsy were evaluated from different manufacturers. Fibers were cleaved, stripped, polished, and inspected for tip uniformity. Fibers were initially tested without contact followed by contact testing using artificial Bego stones. Pre- and postcontact energy outputs were measured by energy detector. Distal tip degradation (burn back) was measured by digital micrometer. Testing was performed on two Ho:YAG lasers (Lumenis VersaPulse 100W and Dornier Medilas H20). All fibers were tested while submerged in water.

RESULTS

No burn back was observed in any fiber tested in still water (without contact). Before and after lithotripsy, a trend existed with fibers demonstrating high burn back and high preablation energy outputs. The majority of these fibers were <300 microm diameter. Conversely, fibers with low burn back showed low preablation energy outputs and were >300 microm diameter.

CONCLUSION

Fiber burn back and energy transmission varied among the fibers tested. Burn back only occurred during lithotripsy. Burn back may be reduced by fiber selection or using low pulse energy. Fiber burn back may affect the efficiency of fragmentation and contribute to decreased longevity of the fiber.

Proof of principle in vitro study of a prototype ultrasound technology to size stone fragments during ureteroscopy

PURPOSE

Proof-of-principle in vitro experiments evaluated a prototype ultrasound technology to size kidney stone fragments.

MATERIALS AND METHODS

Nineteen human stones were measured using manual calipers. A 10-MHz, 1/8'' (10F) ultrasound transducer probe pinged each stone on a kidney tissue phantom submerged in water using two methods. In Method 1, the instrument was aligned such that the ultrasound pulse traveled through the stone. In Method 2, the instrument was aligned partially over the stone such that the ultrasound pulse traveled through water.

RESULTS

For Method 1, the correlation between caliper- and ultrasound-determined stone size was r(2) = 0.71 (P < 0.0001). All but two stone measurements were accurate and precise to within 1 mm. For Method 2, the correlation was r(2) = 0.99 (P < 0.0001), and measurements were accurate and precise to within 0.25 mm.

CONCLUSIONS

The prototype technology and either method measured stone size with good accuracy and precision. This technology may be possible to incorporate into ureteroscopy.

Paediatric painful bladder syndrome/interstitial cystitis: diagnosis and treatment

To describe the pathophysiology, diagnosis and controversies surrounding the diagnosis and pharmacological treatments of painful bladder syndrome/interstitial cystitis (PBS/IC) in children, we reviewed adult and paediatric literature pertaining to PBS/IC. Paediatric PBS/IC presents similarly to adult PBS/IC. The diagnosis is made by exclusion. Paediatric PBS/IC patients complain most commonly of urinary frequency, and abdominal pain occurs in up to 88% of affected children. Enuresis may also be a presenting complaint. Urinalysis and urine cultures are unremarkable. Management of paediatric PBS/IC is similar to that of adult PBS/IC, and non-surgical management includes dietary, lifestyle and pharmacological therapy. Pharmacological options include pentosan polysulfate, amitriptyline, hydroxyzine, cimetidine or intravesical therapies (dimethyl sulfoxide or 'therapeutic solution').

Differences in the clinical presentation of interstitial cystitis/painful bladder syndrome in patients with or without sexual abuse history

PURPOSE

We tested the hypothesis that female patients with interstitial cystitis/painful bladder syndrome with or without a history of prior sexual abuse have different clinical presentations.

MATERIALS AND METHODS

Consecutive newly diagnosed women with interstitial cystitis/painful bladder syndrome were stratified into those with and those without a history of sexual abuse, and cohorts were compared. Analysis included demographics, frequency, nocturia, voided volumes, pelvic pain urgency frequency, interstitial cystitis symptom index and problem index scores, female sexual function index scores and physical examination findings.

RESULTS

There were 119 subjects, 30 (25%) with a history of sexual abuse. Comparing subjects with or without a history of sexual abuse, mean daytime frequency (minutes between voids) was 106 vs 60 (p <0.0001), nocturic episodes was 1.4 vs 3.1 (p = 0.0002) and voided volume was 234 vs 115 cc (p <0.001), respectively. On examination tenderness was more likely elicited on suprapubis, vulva, posterior vaginal wall, cervical motion, levators and rectum (p <0.05) in subjects with a history of sexual abuse. Female sexual function index domain scores were worse for all domains (p <0.05) for subjects with a history of sexual abuse. Age, duration of symptoms, pelvic pain urgency frequency, interstitial cystitis symptom index, interstitial cystitis problem index and hydrodistention volumes were similar.

CONCLUSIONS

Female patients with interstitial cystitis/painful bladder syndrome with a history of sexual abuse have a different clinical presentation compared to those without an abuse history. Patients with a history of abuse present with more pain and fewer voiding problems. Patients with interstitial cystitis/painful bladder syndrome with a sexual abuse history may have increased central sensitization.

Pharmacological management of renal colic in the older patient

Renal colic affects up to 12% of the population. Initial management of most patients is expectant. Acute symptom management of renal colic is best accomplished with a combination of parenteral opioids and NSAIDs. The elderly patient with a kidney stone should be screened for contraindications to NSAID therapy, such as renal failure or previous peptic ulcer disease. Use of parenteral opioids is often necessary during the acute setting, and downward-adjusted doses and monitoring are necessary to prevent associated confusion and respiratory depression. Novel therapy with desmopressin may also be effective for symptom control at the initial presentation, without the adverse effects of opioids or NSAIDs. However, use of desmopressin in the elderly must be undertaken cautiously, given the potential adverse effects of this agent. Many small, distal ureteral stones are treated initially with watchful waiting for the first 2-4 weeks after presentation. The patient should have effective, non-parenteral analgesics for use at home. Included in these agents are oral or suppository NSAIDs and oral opioids. Medical expulsion therapy with alpha-adrenoceptor antagonists or calcium channel antagonists is efficacious. alpha-Adrenoceptor antagonists such as the alpha(1A/)(1)(D)-selective tamsulosin are well tolerated in the elderly and increase the rate of spontaneous stone passage by approximately 50% for small distal stones. These agents also appear to decrease the severity of renal colic. Corticosteroids and calcium channel antagonists are also effective but their use in the elderly is not recommended as first-line therapy.

The role of the bladder surface in interstitial cystitis/painful bladder syndrome

INTRODUCTION

Interstitial cystitis (IC) is a potentially severe and debilitating condition of the bladder. Numerous factors have been implicated in its pathogenesis.

MATERIALS AND METHODS

A literature review was conducted on the following topics: urothelium, mucosal lining, interstitial cystitis, bladder, and glycosaminoglycans.

RESULTS

A commonly proposed cause for IC is a defect or alteration in the bladder surface leading to increased permeability to noxious urinary solutes and ultimately to tissue inflammation and neurogenic upregulation. Support for this concept is drawn from studies of the structure, function, and composition of the bladder surface. The cause(s) of this alteration is not known, although recent research has implicated changes in the levels of growth factors and/or compounds that protect against irritants and potentially "toxic" factors. The etiology of IC is likely multifactorial.

CONCLUSIONS

Alterations of the bladder surface are observed in IC, and may play an important role in the etiology of this condition.

Shock wave lithotripsy correlates with stone density on preoperative computerized tomography

PURPOSE

We reviewed our experience with the Dornier Doli S lithotriptor to address 2 questions. 1) What is the stone-free rate? 2) Can a stone-free outcome be predicted by preoperative computerized tomography?

MATERIALS AND METHODS

The records of 76 consecutive patients undergoing shock wave lithotripsy for solitary urinary calculi 5 to 20 mm in diameter were studied retrospectively. Pretreatment noncontrast computerized tomography was reviewed to determine Hounsfield density. The shock wave lithotripsy outcome was determined at 12 weeks on imaging and categorized as 1) stone free, 2) any residual fragments or 3) stone unchanged.

RESULTS

Of the patients 28 (37%) were stone free, 11 (14%) had residual fragments and 37 (49%) had stones that remained unchanged on computerized tomography after a single treatment with shock wave lithotripsy using a Dornier Doli S. Stones of patients rendered stone free had a lower median density compared to stones in patients with residual fragments and unchanged stones (684 vs 1,034 and 920 HU, respectively, p = 0.04). The stone-free rate for stones less than 1,000 HU was 46% vs 17% for stones 1,000 HU or greater (p = 0.01).

CONCLUSIONS

The combined stone-free and fragmentation rate was 51%, lower than in other published reports. In patients with calculi greater than 1,000 HU shock wave lithotripsy achieved a stone-free rate of only 17%. Patients should be informed of the likelihood of treatment failure or need for auxiliary procedures if the Doli S lithotriptor is used, particularly for stones greater than 1,000 HU.

Contemporary Clinical Presentation of Interstitial Cystitis

For the purpose of presenting a comprehensive review of current information, the medical literature was reviewed to extract data related to the clinical presentation of interstitial cystitis (IC). The most common symptoms at diagnosis are urinary urgency, daytime frequency, dysuria, pain, and nocturia. The most common sites where pain is localized are the suprapubic, pubic, vaginal, and genital areas. Pain is commonly triggered or exacerbated by vaginal intercourse in women or ejaculation in men. The most common findings on physical examination are dysphoric mood, suprapubic tenderness, and anterior vaginal wall tenderness. A voiding diary typically shows an increased number of voids per day and reduced volumes per void. Overall, published reports in the literature indicate that the clinical presentation of IC is variable. IC is readily suggested by history, physical examination, and voiding diary findings.

Interstitial Cystitis and Female Sexual Dysfunction

OBJECTIVES

To use the Female Sexual Function Index (FSFI) to compare female sexual dysfunction in patients with interstitial cystitis/painful bladder syndrome (IC) with that in controls.

METHODS

Consecutive patients with IC and asymptomatic controls were tested for voiding diary voided volumes, Pelvic Pain and Urgency/Frequency Questionnaire scores, and FSFI scores.

RESULTS

Of the 97 subjects, 75 had IC and 22 were controls. The mean age was 38 and 43 years (P = 0.09), the voided volume was 165 mL and 294 mL (P <0.0001), and the Pelvic Pain and Urgency/Frequency Questionnaire score was 18 versus 3 (P <0.0001) for the IC and control groups, respectively. The total adjusted FSFI scores differed between patients with IC and the controls (20.2 +/- 9.6 versus 29.0 +/- 6.8, respectively, P <0.001). Using 26.55 as the cutpoint, 51 patients with IC (68%) had an abnormal FSFI score versus 3 controls (14%; P <0.001). Patients with IC scored worse on all domains of female sexual dysfunction than did the controls (P <0.01).

CONCLUSIONS

The results of our study have shown that female patients with IC have sexual dysfunction, including pain, more commonly than do controls.

Neural Upregulation in Interstitial Cystitis

Interstitial cystitis (IC) is a syndrome of bladder hypersensitivity with symptoms of urgency, frequency, and chronic pelvic pain. Although no consensus has been reached on the underlying cause of IC, several pathophysiologic mechanisms, including epithelial dysfunction, mast cell activation, and neurogenic inflammation, have been proposed. Despite multiple different causes of urinary cystitis, the bladder's response to cystitis is limited and typical. Animal experiments have shown upregulation of proteinase-activated receptors, tryptase, beta-nerve growth factor, inducible nitric oxide synthase, nuclear transcription factor-kappaB, c-Fos, phosphodiesterase 1C, cyclic adenosine monophosphate (cAMP)-dependent protein kinase, and proenkephalin B. After the noxious stimulus has abated, downregulation of genes appears to follow. Distention of the bladder results in the release of adenosine triphosphate (ATP) from urothelial cells, which activates purinergic P2X3 receptors. Activation by ATP of P2X3-expressing afferents is a fundamental signaling factor in bladder sensation and appears to play a role in bladder reflexes. Fos proteins present in spinal cord neurons have been shown to be upregulated in animals that have undergone cyclophosphamide-induced chemical cystitis. These and other findings suggest that neural upregulation occurs both peripherally and centrally in subjects with chronic cystitis. It is unclear whether neural mechanisms and inflammation are the cause of IC or the result of other initiating events. Neural upregulation is known to play a role in the chronicity of pain, urgency, and frequency and represents an exciting area of research that may lead to additional treatments and a better understanding of IC.

Lasers in clinical urology: state of the art and new horizons

We present an overview of current and emerging lasers for Urology. We begin with an overview of the Holmium:YAG laser. The Ho:YAG laser is the gold standard lithotripsy modality for endoscopic lithotripsy, and compares favorably to standard electrocautery transurethral resection of the prostate for benign prostatic hyperplasia (BPH). Available laser technologies currently being studied include the frequency doubled double-pulse Nd:Yag (FREDDY) and high-powered potassium-titanyl-phosphate (KTP) lasers. The FREDDY laser presents an affordable and safe option for intracorporeal lithotripsy, but it does not fragment all stone compositions, and does not have soft tissue applications. The high power KTP laser shows promise in the ablative treatment of BPH. Initial experiments with the Erbium:YAG laser show it has improved efficiency of lithotripsy and more precise ablative and incisional properties compared to Ho:YAG, but the lack of adequate optical fibers limits its use in Urology. Thulium:YAG fiber lasers have also demonstrated tissue ablative and incision properties comparable to Ho:YAG. Lastly, compact size, portability, and low maintenance schedules of fiber lasers may allow them to shape the way lasers are used by urologists in the future.

Dependence of calculus retropulsion on pulse duration during Ho: YAG laser lithotripsy

BACKGROUND AND OBJECTIVES

The purpose of this study was to investigate the effect of optical pulse duration on stone retropulsion during Ho:YAG (lambda = 2.12 microm) laser lithotripsy.

STUDY DESIGN/MATERIALS AND METHODS

A clinical Ho:YAG laser with pulse durations was employed to fragment calculus phantoms and to evaluate stone phantom retropulsion. At a given pulse energy, optical pulse durations were divided into two discrete conditions: short pulse (tau(p): 120 to approximately 190 microseconds at FWHM) and long pulse (tau(p): 210 to approximately 350 microseconds at FWHM). Plaster of Paris calculus phantoms were ablated at different energy levels using optical fibers of varying diameters (273, 365, and 550 microm in core size). The dynamics of the recoil action of a calculus phantom was monitored using a high-speed camera; the laser-induced craters were evaluated with optical coherent tomography (OCT). Bubble formation and collapse were recorded with a fast flash photography setup, and acoustic transients were measured with a hydrophone.

RESULTS

Shorter pulse durations produced more stone retropulsion than longer pulses at any given pulse energy. Regardless of pulse duration, higher pulse energy and larger fibers resulted in larger ablation volume and retropulsion (P<0.05). For shorter pulse durations, more rapid bubble expansion was observed and higher amplitudes of the collapse pressure wave were measured (P<0.05).

CONCLUSION

Less retropulsion and equivalent fragmentation occurred when Ho:YAG pulse duration increased.

Urinary calculus fragmentation during Ho: YAG and Er:YAG lithotripsy

BACKGROUND AND OBJECTIVES

We tested Ho:YAG and Er:YAG laser ablation of human urinary calculi to determine if Er:YAG is a more efficient lithotripsy device.

STUDY DESIGN/MATERIALS AND METHODS

Ablation efficiency of Ho:YAG and Er:YAG lasers was tested at varying energy settings, ranging from the damage threshold to clinical energy setting associated with Ho:YAG laser. Stones of known composition (calcium oxalate monohydrate (COM), cystine, and uric acid (UA)) were irradiated. Crater width, depth, and ablation volumes were determined using an optical coherence tomography (OCT).

RESULTS

For all stones and energy settings, the Er:YAG laser produced deeper craters and larger ablation volumes than Ho:YAG laser. The Ho:YAG laser created wider craters during the multiple pulse process and the shape of craters was irregular.

CONCLUSIONS

The Er:YAG laser is more efficient than the Ho:YAG laser for lithotripsy. The deeper craters produced by the Er:YAG laser is attributed to the high absorption of energy at its wavelength.

Prevalence, diagnosis, characterization, and treatment of prostatitis, interstitial cystitis, and epididymitis in outpatient urological practice: the Canadian PIE Study

OBJECTIVES

To determine the prevalence, diagnostic patterns, and management of prostatitis, interstitial cystitis, and epididymitis (PIE) in Canadian urology outpatient practice.

METHODS

Representative urologists were randomly selected from the Canadian and Quebec Urological Associations. Each patient identified with a PIE diagnosis during a typical 2-consecutive-week period during April 2004 to July 2004 was requested to complete a corresponding Chronic Prostatitis Symptom Index (CPSI), O'Leary-Sant Symptom Index (OSSI), or a Chronic Epididymitis Symptom Index (CESI). Each day the participant urologist completed an outpatient log and a detailed programmed chart review to transcribe demographics, investigations, and treatments associated with each PIE patient.

RESULTS

Sixty-five urologists were invited to participate. Fifty-seven (88%) agreed, and 48 (74%) completed the audit. Of the 8712 patients seen in outpatient practice (average 182 per urologist), 2675 were female and 6037 male. Prostatitis was identified in 2.7% of the men (n = 166; mean age 50 years; mean duration 3.1 years; mean CPSI score 19.7), interstitial cystitis in 2.8% of patients (n = 242; 211 women [7.9%], 26 men [0.4%]; mean age 50.2 years, mean duration 4.5 years, mean OSSI score 11.8), and epididymitis in 0.9% of men (n = 57; mean age 41.1 years, mean duration 2.5 years, mean CESI score 15.5). There was wide variance in investigations and treatments.

CONCLUSIONS

This prospective audit indicates that prostatitis might not be as common as frequently believed and that interstitial cystitis is more common, and it represents the first estimate of the prevalence of epididymitis in urologic practice. The wide variance in investigations and treatments confirms the need for practice management guidelines.

Performance and Safety of Holmium: YAG Laser Optical Fibers

BACKGROUND AND PURPOSE

Lower-pole ureteronephroscopy requires transmission of holmium:YAG energy along a deflected fiber. Current ureteroscopes are capable of high degrees of deflection, which may stress laser fibers beyond safe limits during lower-pole use. We hypothesized that optical fiber and safety measures differ among manufacturers.

MATERIALS AND METHODS

Small (200-273-microm) and medium-diameter (300-400-microm) Ho:YAG fibers were tested in a straight and 180 degrees bent configuration. Energy transmission was measured by an energy detector. Fiber durability was assessed by firing the laser in sequentially tighter bending diameters. The fibers were bent to 180 degrees with a diameter of 6 cm and run at 200- to 4000-mJ pulse energy to determine the minimum energy required to fracture the fiber. The bending diameter was decreased by 1-cm increments and testing repeated until a bending diameter of 1 cm was reached. The maximum deflection of the ACMI DUR-8E ureteroscope with each fiber in the working channel was recorded. The flow rate through the working channel of the DUR-8E was measured for each fiber.

RESULTS

The mean energy transmission differed among fibers (P < 0.001). The Lumenis SL 200 and the InnovaQuartz 400 were the best small and medium-diameter fibers, respectively, in resisting thermal breakdown (P < 0.01). The Dornier Lightguide Super 200 fractured repeatedly at a bend diameter of 2 cm and with the lowest energy (200 mJ). The other small fibers fractured only at a bend diameter of 1 cm. The Sharplan 200 and InnovaQuartz Sureflex 273T were the most flexible fibers, the Lumenis SL 365 the least. The flow rate was inversely proportional to four times the power of the diameter of the fiber.

CONCLUSIONS

Optical performance and safety differ among fibers. Fibers transmit various amounts of energy to their cladding when bent. During lower-pole nephroscopy with the fiber deflected, there is a risk of fiber fracture from thermal breakdown and laser-energy transmission to the endoscope. Some available laser fibers carry a risk of ureteroscope damage.

What is the value of cystoscopy with hydrodistension for interstitial cystitis?

OBJECTIVES

To determine the utility of cystoscopy with hydrodistension for the diagnosis and therapy of interstitial cystitis. Cystoscopy with hydrodistension is the most commonly performed diagnostic test and procedure in patients with interstitial cystitis.

METHODS

Eighty-four consecutive patients with interstitial cystitis (68 women and 16 men) were studied retrospectively. The patients underwent history and physical examination, urinalysis, and urine culture and filled in a voiding diary and pain urgency frequency questionnaire. Cystoscopy with hydrodistension was performed in 47 patients. Patients who had and had not undergone hydrodistension were compared. Patients who underwent hydrodistension were characterized and followed up for response.

RESULTS

The mean patient age was 41 years, mean daily voided volume was 98 mL, mean number of nocturnal episodes was 3, and pain urgency frequency score was 21. Comparing patients undergoing versus not undergoing hydrodistension, pain was reported in 61% versus 25% (P = 0.03), vaginal pain in 62% versus 32% (P = 0.02), and dyspareunia or ejaculatory pain in 67% versus 29% (P < 0.01), respectively. All other parameters were statistically similar. Of the patients undergoing hydrodistension, 43 had follow-up and 24 (56%) reported improvement (mean duration of 2 months). Of the patients with and without improvement, no difference was found in mean age (40 versus 46 years, P = 0.20), duration of symptoms (7 versus 7 years, P = 0.92), anesthetic capacity (722 versus 721 mL, P = 0.99), or glomerulation grade (P = 0.61), respectively.

CONCLUSIONS

Cystoscopy with hydrodistension provided little useful information above and beyond the history and physical examination findings. As therapy, 56% of patients reported improvement, but the duration was short lived.

Review of laser fibers: a practical guide for urologists

Holmium:YAG lithotripsy requires transmission of optical energy using laser fibers. Optical fibers may be subjected to severe angular deflection and bending during flexible nephroscopy or flexible ureteronephroscopy. Irradiation of a deflected fiber in a tight bending radius may produce fiber failure and consequent irradiation of the ureteroscope, with risk of instrument damage and patient injury. We review the physics and engineering aspects of optical fibers to explain why fibers fail.

Dependence of calculus retropulsion dynamics on fiber size and radiant exposure during Ho:YAG lithotripsy

During pulsed laser lithotripsy, the calculus is subject to a strong recoil momentum which moves the calculus away from laser delivery and prolongs the operation. This study was designed to quantify the recoil momentum during Ho:YAG laser lithotripsy. The correlation among crater shape, debris trajectory, laser-induced bubble and recoil momentum was investigated. Calculus phantoms made from plaster of Paris were ablated with free running Ho:YAG lasers. The dynamics of recoil action of a calculus phantom was monitored by a high-speed video camera and the laser ablation craters were examined with Optical Coherent Tomography (OCT). Higher radiant exposure resulted in larger ablation volume (mass) which increased the recoil momentum. Smaller fibers produced narrow craters with a steep contoured geometry and decreased recoil momentum compared to larger fibers. In the presence of water, recoil motion of the phantom deviated from that of phantom in air. Under certain conditions, we observed the phantom rocking towards the fiber after the laser pulse. The shape of the crater is one of the major contributing factors to the diminished recoil momentum of smaller fibers. The re-entrance flow of water induced by the bubble collapse is considered to be the cause of the rocking of the phantom.

How do residents manage personal finances?

BACKGROUND

We examined three research questions: How do residents' debts and savings compare to the general public? How do surgical residents' financial choices compare to other residents? How may institutions help residents' personal financial decisions?

METHODS

The Survey of Consumer Finances was modified and piloted tested to elicit financial information. The instrument was completed by 612 residents at 8 programs.

RESULTS

Only 60% of residents budgeted expenses, and 25% and 10% maintained cash balances <611 dollars and unpaid credit card balances >10,000 dollars, respectively. Compared with controls, residents held greater median ratios of debt to household income (2.46 vs. 1.06, P <0.0001), fewer assets to income (0.64 vs. 2.28, P <0.0001), less net wealth to income -1.43 vs. 0.90, P <0.0001), and lower retirement savings balance to household income (0.01 vs. 0.12, P <0.0001). Surgery residents were the least financially conservative group. Mean annual resident contributions to retirement accounts were $1532 higher at institutions with versus without retirement plans (P <0.01).

CONCLUSIONS

Resident debts are higher and savings lower than the general public. This behavior is most common among surgery residents. Residents save more for retirement when they are eligible for tax-deferred retirement plans. Graduate medical programs should instruct residents on financial management.

Personal finances of residents at three Canadian universities

OBJECTIVES

To address 3 research questions (What financial choices do residents make? Are the financial choices of residents similar to those of the general public? Are the financial choices of surgical residents reasonable?), we examined financial data from Canadian residents.

METHODS

A written survey was administered to 338 residents (103 of them surgical residents) at 3 Canadian training institutions (University of Toronto, Queen's University and University of Manitoba). Resident household cash flows, assets and liabilities were characterized. Finances for residents were compared with those of the general public, by means of the Survey of Household Spending and Survey of Financial Security.

RESULTS

Median resident income was 45,000 dollars annually (Can dollars throughout). With a working spouse, median household income was 87,500 dollars. Among residents, 62% had educational debt (median 37,500 dollars), 39% maintained unpaid credit-card balances (median 1750 dollars), 36% did not budget expenses, 25% maintained cash reserves <275 dollars, and 22% contributed neither to retirement nor nonretirement investments. Residents spent more on vehicles compared with members of the general public (median 17,500 dollars v. 10,720 dollars, p = 0.002) and on monthly housing (median 875 dollars v. 729 dollars, p < 0.001), respectively. Residents were more likely to carry student loans than people in the general population (61% v. 21%), more likely to carry vehicle loans (74% v. 29%) and less likely to carry credit-card debts (39% v. 50%, respectively). Surgical residents had income expectations after graduation higher than current billings justified. Fewer surgical (69%) than anesthesiology residents (88%, p < 0.05) contributed to Registered Retirement Savings Plans.

CONCLUSIONS

From this limited sample, residents spend more than age- and income-matched members of the general public. Many residents save too little, fail to budget, and carry high educational and credit-card debts. Surgical residents' expectations of future income may be unrealistic. Further study is warranted.

Calculus fragmentation in laser lithotripsy

The intracorporeal treatment of urinary calculi with lasers is presented, which describes laser-calculus interactions associated with lithotripsy. Reliable fragmentation of calculi with diverse compositions and minimal collateral tissue damage are primarily contingent upon laser parameters (wavelength, pulse duration, and pulse energy) and physical properties of calculi (optical, mechanical, and chemical). The pulse duration governs the dominant mechanism in calculi fragmentation, which is either photothermal or photoacoustical/photomechanical. Lasers with long pulse durations (i.e. > tens of micros) induce a temperature rise in the laser-affected zone with minimal acoustic waves; material is removed by means of vaporization, melting, mechanical stress, and/or chemical decomposition. Short-pulsed laser ablation (i.e. < 10 micros), on the other hand, produces shock waves, and the resultant mechanical energy fragments calculi. Work continues throughout the world to evaluate the feasibility of advanced lasers in lithotripsy and to optimize laser parameters and light delivery systems pertinent to efficient fragmentation of calculi.