Intrarenal Stones Research Articles

Sonographic detection of renal and ureteral stones: value of the twinkling sign

To compare the detection of urinary stones using standard gray scale ultrasound for diagnostic accuracy using the color Doppler "twinkling sign". Our study population consisted of forty-one patients who demonstrated at least one urinary stone on unenhanced CT evaluation of the kidneys or ureters. Each patient was evaluated using gray scale ultrasound and color Doppler imaging by an observer who was blinded to the CT results. Seventy-seven stones were present in 41 patients, including 47 intrarenal stones, 5 stones in the renal pelvis, 8 stones at the ureteropelvic junction, 5 ureteral stones and 12 stones at the ureterovesical junction. Based upon gray scale sonography the diagnosis of stone was made with confidence in 66% (51/77) of locations. Based upon Doppler sonography using the twinkling sign, the diagnosis of stone was made with confidence in 97% (75/77) of locations. Clustered ROC analysis demonstrated that the Doppler twinkling sign (Az = 0.99) was significantly better than conventional gray scale criteria (Az = 0.95) for the diagnosis of urinary stones (p = 0.005, two-sided test). The color Doppler twinkling sign improves the detection, confidence and overall accuracy of diagnosis for renal and ureteral stones with minimal loss of specificity.

UROLOGIST VERSUS RADIOLOGIST-MADE PCNL TRACTS; THE UK EXPERIENCE

To assess the feasibility of laparoscopy in the treatment of pediatric urolithiasis, we report our experience with the transperitoneal laparoscopic removal of stones.Renal pelvic stones of size ≥1 cm on ultrasound were included for laparoscopic pyelolithotomy while smaller stones were managed with shock-wave lithotripsy monotherapy. Intrarenal stones, calyceal stones, complete staghorn stones, multiple stones and kidneys with intrarenal pelvis were excluded. Ureteric stones included for laparoscopic ureterolithotomy were of size ≥1 cm in the upper, mid or lower ureter, and smaller stones not responding to non-operative treatment.A total of 22 procedures were performed: 12 pyelolithotomies, and 8 lower and 2 upper ureterolithotomies. Complete removal of calculi was accomplished in 21 (95.45%) procedures. Complications associated with laparoscopic lithotomy included urinoma (4.54%), failure (4.54%) and omental prolapse (4.54%).Laparoscopic lithotomy is safe and feasible in pediatric urolithiasis with pyelic and ureteric stones, with minimal complications and failure rate.

Pediatric Ureteroscopic Management of Intrarenal Calculi

Data addressing ureteroscopic management of intrarenal calculi in prepubertal children are limited. We reviewed our experience from January 2002 through December 2007. We retrospectively reviewed ureteroscopic procedures for intrarenal calculi in children younger than 14 years. Stone-free status was determined with postoperative imaging. Multiple logistic regression analysis was used to assess the influence of preoperative factors on initial stone-free status and the need for additional procedures. Intrarenal calculi were managed ureteroscopically in 52 kidneys in 50 children with a mean age of 7.9 years (range 1.2 to 13.6). Mean stone size was 8 mm (range 1 to 16). Stone-free rate after a single ureteroscopic procedure was 50% (25 of 50 patients) on initial postoperative imaging and 58% (29 of 50) with extended followup. Initial stone-free status was dependent on preoperative stone size (p = 0.005) but not stone location. Additional stone procedures were required in 18 upper tracts. Younger patient age (p = 0.04) and larger preoperative stone size (p = 0.002) were associated with the need for additional procedures. Additional procedures were required in more than half of the stones 6 mm or larger but in no stone smaller than 6 mm. Ureteroscopy is a safe method for the treatment of intrarenal calculi in the prepubertal population. Our ureteroscopic stone-free rate for intrarenal stones is lower than that reported for ureteral stones. Parents should be informed that additional procedures will likely be required, especially in younger patients and those with stones larger than 6 mm.

Eighteen-Year Experience with the Medstone STS Lithotripter: Safety, Efficacy, and Evolving Practice Patterns

To evaluate trends in safety, efficacy, and practice patterns for shockwave lithotripsy (SWL) procedures performed during a 18-year period and correlate the findings with recent evidence-based practice guidelines. From January 1988 to June 2006, 66,819 SWLs were performed using the Medstone STS lithotripter in patients with radiologic evidence of stones in the kidney or ureter. Treatment characteristics, such as stone location and size, need of re-treatment, and final success rate were recorded. The procedures were further divided by year for statistical consideration. Statistical analysis was performed using Student t test; P < 0.05 was considered significant. Overall SWL success rate was 85% (39,667/46,669), and the overall re-treatment rate was 7.2% (3,417/46,669). There was no significant change in the overall proportion of lower-pole calculi managed with SWL, although there was a significant decrease in the proportion of SWL used for lower calix stones larger than 16 mm in the time period after 2000 (P = 0.006). There was a steady increase in the number of procedures performed for renal calculi in other locations per year, in particular for intrarenal calculi smaller than 20 mm. Intrarenal stones larger than 30 mm decreased as a proportion of procedures per year (P = 0.048) There was no significant change in the proportion of upper and distal ureteral stones managed, corresponding to a solid plateau in the percentage of SWL performed per year. Our study did not demonstrate an overall drop in SWL; however, it did show the interference of endoscopic procedures on two case scenarios. There was a significant decrease (P = 0.048) in SWL for renal stones larger than 30 mm, and the same trend was noted for lower calix stones larger than 15 mm (P = 0.06).

Endoluminal Isoproterenol Irrigation Decreases Renal Pelvic Pressure During Flexible Ureterorenoscopy: A Clinical Randomized, Controlled Study

ObjectivesIrrigation during ureterorenoscopic procedures causes increased pelvic pressure (PP), which may lead to intrarenal backflow with potential harmful consequences. This study aims to investigate PP response to intraluminal administration of isoproterenol (β-agonist; ISO) during flexible ureterorenoscopy. MethodsTwelve patients admitted for retrograde intrarenal stone surgery (RIRS) were included. Patients were randomized to (1) irrigation with saline (n=6) or (2) irrigation with ISO 0.1μg/mL (n=6). Irrigation rate was standardized to 8mL/min. A ureteral catheter was retrogradely placed in the renal pelvis for PP measurements. PP, heart rate (HR), and mean arterial pressure (MAP) were also measured. ResultsBaseline PP was 12.1±4mm Hg in the saline group and 10.3±4mm Hg in the ISO group (p=0.44).In the saline group, PP increased to a mean 33±12mm Hg during ureterorenoscopy. In the ISO group, PP was a mean 19±3mm Hg (p=0.029).During endoscopy, PP peaks as high as 328mm Hg were noted during saline irrigation. The number of pressure peaks above 50mm Hg was minimized dramatically during ISO irrigation (p=0.035). No systemic side effects to ISO irrigation were observed. ConclusionFor the first time, a randomized, controlled human study demonstrates that pharmacologic modulation of the ureter is possible during upper urinary tract endoscopy. The ability to relax ureteral tone during endoscopy may have clinical advantages.

Safety and Efficacy of Flexible Ureterorenoscopy and Holmium:YAG Lithotripsy for Intrarenal Stones in Anticoagulated Cases

We compared perioperative outcomes in patients undergoing ureterorenoscopy and Ho:YAG lithotripsy for renal calculi with or without anticoagulation. We reviewed the records of all patients undergoing flexible ureterorenoscopy and Ho:YAG lithotripsy for renal calculi at 2 institutions from 2001 to 2007. We identified 37 patients on anticoagulation with Coumadin, clopidogrel or aspirin in whom anticoagulation therapy was not discontinued before surgery. Data on the anticoagulation group were retrospectively compared to those on a contemporary matched cohort of 37 controls without anticoagulation who underwent a similar operative procedure. The 2 groups were compared with regard to the stone-free rate, and intraoperative and postoperative complications with specific reference to bleeding and thromboembolism. The 2 groups were matched for stone size, stone location, number of stones, bilateral procedures and concomitant ureteral stones. Anticoagulation group patients were older (58.2 vs 50.4 years, p = 0.0209) and had a greater American Society of Anesthesiologists score (2.8 vs 1.9, p <0.0001) compared to the control group. No procedure had to be terminated in the anticoagulation group due to poor visibility from bleeding. The median postoperative hemoglobin decrease was greater in the anticoagulation group than in the control group (0.6 vs 0.2 gm/dl, p <0.0001). The stone-free rate (81.1% vs 78.4%, p = 0.7725), intraoperative complications (0% vs 3%, p = 0.3140), postoperative complications (11% vs 5%, p = 0.3943) and hemorrhagic or thromboembolic adverse events were comparable in the 2 groups. When necessary, ureterorenoscopy and Ho:YAG lithotripsy can be performed safely and efficaciously for renal calculi in patients on anticoagulation therapy without the need for perioperative manipulation.

Shock Wave Lithotripsy Success for Renal Stones Based on Patient and Stone Computed Tomography Characteristics

To determine the patient and noncontrast computed tomography (NCCT) stone characteristics that predict either of 2 extracorporeal shock wave lithotripsy (ESWL) outcomes: stone-free (SF) status or ESWL success. The records of 200 consecutive patients with nephrolithiasis treated with ESWL were reviewed. Patient age, sex, stone laterality, body surface area, body mass index, maximal stone dimension, mean stone Hounsfield units (HU), stone Hounsfield density, skin-to-stone distance (SSD), and intrarenal stone location were studied as potential predictors. Patients with no calcifications on postoperative kidneys, ureters, and bladder (KUB) at 6 weeks were defined as SF. ESWL success was defined as SF or remaining stone fragments less than 4 mm. Intrarenal stone location was found to be the only predictor of SF status. Renal pelvic/ureteropelvic junction (UPJ) stones cleared better than calyceal stones, and upper/middle calyceal stones cleared better than lower calyceal stones. Stone size, mean HU, and location predicted ESWL fragmentation success. Smaller stones and stones with lower mean HU levels were more successfully fragmented. Higher SF and ESWL success rates were found with a shorter SSD among calyceal stones when renal pelvic/UPJ stones were excluded from analysis. Stone location is the most important factor in achieving SF status after ESWL. NCCT stone characteristics such as stone size, mean HU, and intrarenal location are important predictors of ESWL success.

41 Retrograde intrarenal stone surgery in ESWL resistant kidney stones

Introduction: The newer flexible ureteroscopes, 150–200 micron Holmium laser fibres and superflexible Dormias have made stone treatment in all parts of the kidney possible. This evaluation concerns the outcome of Retrograde Intrarenal Stone Surgery (RIRS) in ESWL‐resistant kidney stones.Material and methods: Thirty‐eight consecutive patients (18 males/20 females) were followed. All patients had undergone ESWL without success. Calculi ranged from 3 to 20 mm (mean 9 mm). In 32 cases stones were fragmented using Holmium laser, and in 6 cases stones were extracted with a zero tip Dormia without fragmentation. Sixteen patients had lower calyceal calculi and eight had abnormal upper tract anatomy. Follow‐up: IVP was performed 6–8 weeks posttreatment.Results: In all cases the stones were reached and fragmented to some extend. Complete stone freedom was found in 22/38 (58%) patients after one RIRS procedure and 4 (11%) had residual fragments &lt;4 mm which were expected to pass spontaneously. In the remaining 12 patients, who initially had larger stones (mean 11.3 mm), the residual fragments ranged from 5 to 15 mm. Three patients underwent an additional RIRS following which they were stone free. The overall success rate was 76%. There were no major complications.Conclusions: RIRS is a safe procedure with high success rate and low complication rate. Patients with stones &gt;1 cm, stones in the lower pole and with abnormal renal abnormality may require more than one sitting.

Retrograde intrarenal stone surgery for extracorporeal shock-wave lithotripsy-resistant kidney stones

The newer flexible ureteroscopes, 150-200-microm holmium YAG laser fibres and superflexible Dormia baskets have made it possible to reach and treat stones in all parts of the kidney. The object of this evaluation was to study the outcome of retrograde intrarenal stone surgery (RIRS) for extracorporeal shock-wave lithotripsy (ESWL)-resistant kidney stones. A total of 38 consecutive patients (18 males, 20 females) participated in the study. All patients had undergone ESWL prior to RIRS without success. In all cases the stones could be reached with the endoscope. Calculi ranged in size from 3 to 20 mm (mean 9 mm). In 32 cases the stones were fragmented using a holmium YAG laser and in six the stones could be extracted using zero-tip Dormia baskets without fragmentation. Sixteen patients had lower calyceal calculi and eight had an abnormal anatomy of the upper urinary tract. Intravenous pyelography was performed 6-8 weeks after the treatment. In all cases the stones could be reached and fragmented to some extent. After a single RIRS procedure, 22/38 patients (58%) were completely stone-free at follow-up, and four (11%) had residual fragments < or = 4 mm in size that were expected to pass spontaneously. Of the remaining 12 patients, who initially had larger stones (mean 11.3 mm), the residual fragments ranged in size from 5 to 15 mm. Three patients underwent an additional RIRS procedure, after which they were all completely stone-free, resulting in an overall success rate of 76%. There were no major complications. RIRS is a safe procedure with a high success rate and a low complication rate for ESWL-resistant renal stones. Patients with larger stones (> 10 mm), those with stones in the lower pole and those with an abnormal renal anatomy may require more than one procedure.

Ureterorenoscopic Approach to the Symptomatic Caliceal Diverticulum

Purpose We evaluated ureterorenoscopy as a treatment approach to symptomatic caliceal diverticula. Materials and Methods Since 1989, 20 women and 6 men suffering from pain, recurrent urinary tract infections or urosepsis were treated using flexible ureterorenoscopy, balloon dilation or incision of the diverticular neck and subsequent intrarenal stone fragmentation when needed. Results Of 19 upper and middle caliceal diverticula 16 (84%) and 2 of 7 lower caliceal diverticula were successfully identified. The orifice to the diverticular cavity was dilated and the stone was fragmented. Of the patients 13 were treated as outpatients and 10 required a 1-night hospital stay. Of those patients in whom the diverticulum could be entered and the stone fragmented 100% were symptom-free at a mean followup of 39 months. One patient required repeat treatment to remove residual stone. Conclusions Ureterorenoscopy produces minimal morbidity and is an effective treatment of upper and middle caliceal diverticula.

Use of profile view of kidney for spatial localization of intrarenal stones

Profile view of the kidney obtained by “reverse oblique” x-ray projection was found to be useful in the spatial localization of intrarenal stones. The patient's position on the x-ray table is described, and 4 cases of patients with renal stones are illustrated.