Sonographic evaluation of renal stones treated by extracorporeal shock-wave lithotripsy

Management of Clinically Insignificant Residual Fragments following Shock Wave Lithotripsy

Clinically insignificant residual fragments (CIRFs) are small fragments (less than 5 mm) that are present in upper urinary tract at the time of regular post-SWL followup. The term is controversial because they may remain silent and asymptomatic or become a risk factor for stone growth and recurrence, leading to symptomatic events, and need further urologic treatment. Although a stone-free state is the desired outcome of surgical treatment of urolithiasis, the authors believe that the presence of noninfected, nonobstructive, asymptomatic residual fragments can be managed metabolically in order to prevent stone growth and recurrence. Further urologic intervention is warranted if clinical indications for stone removal are present.

Effectiveness of ultrasonography in the postoperative follow-up of pediatric patients undergoing ureteroscopic stone manipulation

OBJECTIVES

To evaluate the effectiveness of ultrasonography and to determine whether ionizing radiation is necessary in the postoperative follow-up of children undergoing ureteroscopy.

METHODS

We reviewed the charts of 49 children who underwent 51 ureteroscopic procedures for ureteral calculi. Renal ultrasound and intravenous urography were performed in all patients at 3 months after surgery for postoperative evaluation.

RESULTS

In three cases, stones migrated to the kidney. Retrograde intrarenal surgery was performed in two patients and one patient required shockwave lithotripsy to become stone-free. Fourty-six children were completely stone-free and 3 had residual fragments on plain film in the postoperative 3 month. The sensitivity, specificity, negative and positive predictive values of ultrasonography for detecting hydronephrosis were 85.7, 100, 97.7 and 100%, respectively. Two patients under observation and three patients under medical expulsive therapy had resolution of hydronephrosis on follow-up. One patient required ureteroscopy for residual obstructing fragments.

CONCLUSIONS

Ultrasonography has limited accuracy for detecting residual ureteral stones, but it is a highly specific and reasonably sensitive test for detecting hydronephrosis. A combination of ultrasonography and plain film is a safe and effective imaging procedure in postoperative follow-up of children undergoing ureteroscopy.

Evaluation of the upper urinary tract using transureteric ultrasound--a review of the technique and typical imaging appearances

Ureteric strictures and pelviureteric junction obstruction often present a diagnostic conundrum to radiologists, particularly after the first-line investigations have failed to provide a definitive answer. Transureteric ultrasonography (TUU) is a relatively novel technique performed by the radiologist, which uses a miniature endoluminal ultrasound probe to interrogate the ureteric anatomy and peri-ureteric soft tissues. In this review, we discuss how TUU is performed, and the normal imaging appearances of the ureter and surrounding anatomical structures. We also focus on the various pathological processes that can be accurately evaluated or diagnosed using TUU including lymphadenopathy, calculi, ureteric neoplasms, ureteritis, crossing vessels and aneurysms. As TUU is not well established in UK practice as yet, we suggest possible indications for its use in the diagnostic work-up of urological patients and future applications.

Elevated plasma concentrations of transforming growth factor-beta 1 in patients with unilateral ureteral obstruction

We measured plasma concentrations of TGF-beta 1 in patients with obstructive ureteral calculi and compared them with the plasma concentrations of healthy volunteers. The present study was a prospective study containing a homogenous group of patients with unilateral ureteral obstruction (UUO). The study consisted of patients with ureteral stones less than 7 mm in diameter that caused mild to moderate obstruction. All patients were referred by the emergency department of our hospital and examined between April 2003 and April 2004. The presence and characteristics of both stone and obstruction were determined by plain abdominal x-ray and gray-scale ultrasonography (US). Blood samples were collected from both patients and control individuals on admission and 1 week after conservative follow-up. The plasma TGF-beta 1 concentration was determined using a quantitative sandwich enzyme immunoassay specific for TGF-beta 1. There were 35 patients with 20 women and 15 men (average age 26.8+/-5.9 years), and 15 volunteers in the control group, with nine women and six men (average age 24.2+/-4.5 years). Average stone size was 5.6 mm+/-1.2 mm (range 3.5-7) for the patient group. US showed the presence of mild hydronephrosis in 24 and moderate hydronephrosis in 11 patients. Plasma concentrations of TGF-beta 1 in patients with ureteral obstruction (1,117+/-5.8 ng/ml, range 36-2,442 ng/ml) were significantly higher than those in the healthy control group (32+/-4 ng/ml) on admission (P<0.001). There was a significant increase in TGF-beta 1 plasma concentrations in the patient group (33,525+/-6.8 ng/ml, range 1,107-73,288 ng/ml) after 1 week follow-up (P<0.001). Ureteral obstruction increases plasma TGF-beta 1 concentrations in patients with ureteral stones as in UUO models in animal studies. A concomitant treatment with an anti-fibrotic agent may reduce the incidence of renal injury during obstruction.

Calcium oxalate monohydrate binding protein: a diagnostic biomarker for calcium oxalate kidney stone formers

Urinary oxalate is a biomarker for calcium oxalate kidney stone disease; however, its assay is insensitive and nonspecific. Calcium oxalate monohydrate (COM) binding protein (45 kDa) is a promoter of calcium oxalate kidney disease, which is markedly upregulated by oxalate induced oxidative stress. The current study was carried out to evaluate whether COM binding protein can serve as a diagnostic marker for calcium oxalate kidney stone formers. COM binding protein was isolated, purified and antibody was raised against it in rabbits. Urine samples (24 h) were collected from patients suffering from various kidney diseases such as acute nephritis, chronic nephritis, nephrotic syndrome, calcium oxalate (CaOx) stone formers, uric acid stone formers, struvite stone formers and calcium phosphate stone formers. This COM binding protein was quantified by an in house ELISA method and the excretion was found to lie between 2 and 3 mg in control samples, while in CaOx stone formers it was detected between 11 and 19 mg. Urinary risk factors were assayed. We conclude that COM binding protein can serve as a diagnostic marker for CaOx stone formers.

Prospective study on ultrasonography plus plain radiography in predicting residual obstruction after extracorporeal shock wave lithotripsy for ureteral stones

OBJECTIVES

To compare ultrasonography (US) and plain radiography with intravenous urography (IVU) in predicting ureteral obstruction after in situ extracorporeal shock wave lithotripsy (ESWL) for ureteral stones.

METHODS

From April 1998 to September 2000, 100 consecutive patients with solitary ureteral stones were treated by primary in situ ESWL. ESWL failures were salvaged by ureteroscopic lithotripsy. Ninety-three patients completed the follow-up assessment. US and IVU were performed when plain radiography showed no residual stone. The occurrence of hydronephrosis on US was compared with IVU, the reference standard for ureteral obstruction.

RESULTS

Of the 93 patients, 72 were men and 21 women (mean age 52 years; mean stone size 11.2 mm). ESWL successfully treated 70 ureteral stones (75%), and the 23 failures were treated by ureteroscopic lithotripsy. Sixty-nine patients without hydronephrosis on US had no ureteral obstruction on IVU. Of the 24 patients who had hydronephrosis on US, 8 had ureteral obstruction on IVU. Of the 85 patients who had no ureteral obstruction on IVU, 69 patients showed no evidence of hydronephrosis on US. However, all patients with ureteral obstruction on IVU demonstrated hydronephrosis on US. The sensitivity, specificity, and positive and negative predictive value concerning sonographic hydronephrosis in the prediction of ureteral obstruction was 100%, 81%, 33%, and 100%, respectively. US alone could not define the cause of ureteral obstruction.

CONCLUSIONS

Plain abdominal radiography plus US is highly sensitive for screening ureteral obstruction after primary in situ ESWL for ureteral calculi. It can save up to 74% of patients from the potential risk of IVU. The detection of the cause of obstruction by IVU is only necessary when sonographic evidence of hydronephrosis is present.

Stone disease

Imaging studies used for the detection and characterization of urinary tract calculi are presented in this article. Comparisons of traditional imaging studies are made with noncontrast helical CT scanning, the most recent addition to stone imaging. Imaging findings for noncontrast helical CT and an approach to dealing with various combinations of CT studies are also presented.

Management of residual stones

Stone-free status is highly dependent on selection of the appropriate surgical technique, which should be tailored according to the individual stone and patient parameters. Although a stone-free state is the desired outcome of surgical intervention of urolithiasis, the authors believe that the presence of noninfection, nonobstructive, asymptomatic postprocedural residual fragments can be managed metabolically in order to prevent stone growth adequately. Further surgical intervention in the case of residual fragments is warranted if the clinical indications that prompted the original surgery persist.

Endoureteral sonography to define the anatomy of the obstructed ureteropelvic junction

Endoluminal ultrasound of the obstructed ureteropelvic junction (UPJ) provides accurate anatomic information not available through other studies. Endoluminal ultrasonography in the evaluation of the obstructed UPJ can be extremely valuable and its use can be expected to expand with increasing experience with the techniques. The anatomy demonstrated through the fine resolution of this technique may ultimately provide the key to the selection of optimal therapy for the obstructed UPJ.

Improved sonographic visualization by fluid challenge method of renal lithiasis in the nondilated collecting system. Experience in seven cases

Ultrasound is an effective means of detecting renal stones in patients with hydronephrosis. The filled urinary bladder in a normal person under hydration frequently results in the sonographic appearance of minimal or moderate hydronephrosis. For optimal visualization of stones and associated acoustic shadows, six patients with radiographically opaque renal stones were evaluated with fluid-loaded renal ultrasonography, which was compared to conventional renal sonogram in basal state. Although ultrasound in basal state can be used for detection of intrarenal lithiasis, fluid-challenged renal sonogram appears more accurate for the determination of contour, location, size, and number of small stones. In one case, this fluid-loaded ultrasound well demonstrated the tramline appearance of an isolated renal artery, which mimics stone before fluid challenge.

Patient evaluation. Laboratory and imaging studies

The evaluation of urolithiases, in terms of calculus detection and evaluation of the morphology and function of the kidneys, continues to be refined with advances in imaging technology. The most significant recent advance is use of helical or spiral CT scan for the accurate delineation of renal and ureteral calculi in the acute setting. This may provide an accurate, rapid, and cost-effective method of patient evaluation. The alternative approach is to use plain abdominal radiography to detect renal or ureteral calculi. Noncontrast-enhanced helical or spiral CT scanning has its greatest impact in patients with negative abdominal radiographs or in those patients with suspected urinary colic in whom renal but not ureteral calculi are seen. A supplemental intravenous urogram can be used, as appropriate, to evaluate renal function and degree of obstruction on both the involved and uninvolved side. Combined abdominal radiography and sonography may be used for calculus detection and demonstration of obstruction. Sonography is an operator-dependent technique requiring expertise, experience, and adequate imaging equipment for satisfactory results. Physiologic study of renal blood flow and urinary dynamics using Doppler techniques are possible, though considered to be in the realm of clinical investigation at this time. Sonography has a valuable role in the serial evaluation of chronic stone formers with a history of recurrent urinary infections related to obstruction or reflux. Radiography, fluoroscopy, and sonography are the imaging, methods used in ESWL treatment in preprocedure and postprocedure.

Potential for inter-observer and intra-observer variability in x-ray review to establish stone-free rates after lithotripsy

The potential for variability among observers interpreting diagnostic tests is well known but has not been well established for radiological imaging of urolithiasis. We measured the inter-observer and intra-observer variability in the reporting of plain abdominal films and tomograms from patients who had undergone extracorporeal shock wave lithotripsy (ESWL). Unlabeled copies of the plain abdominal films and tomograms for 58 patients were individually submitted to 3 different radiologists. Selected films from 25 patients were resubmitted to the same radiologists. We found differences among radiologists reporting plain abdominal films alone 52% of the time and even by the same radiologist rereading the films 24% of the time. Tomograms alone decreased the uncertainty but differences still occurred among radiologists 24% of the time and with themselves 16% of the time. When plain abdominal films and tomograms were read together there were differences among radiologists 28% of the time and with themselves 7% of the time but these were usually minor. We concluded from this study that the plain abdominal film alone was frequently difficult to interpret, resulting in uncertainty about the presence or absence of residual stone fragments. Tomograms alone or a plain abdominal film plus tomograms is superior to a plain abdominal film alone. Finally, radiological assessment with all modalities probably overestimates stone-free rates after ESWL even without consideration of the potential for reporting variability among observers.

Prospective study to compare the efficacy of plain X-ray, renal tomography and renal ultrasound in post-ESWL follow-up

A prospective study was performed to compare the efficacy of plain X-ray, renal tomography and renal ultrasound for the evaluation of the presence of residual fragments and the size of the fragments on 108 patients at 1 month follow-up after ESWL. Ultrasound appeared to be sensitive in identifying the residual fragments. Renal tomography more specific in the evaluation fragment size. We suggest that the one month follow-up evaluation could be limited routinely to ultrasonography and abdominal X-ray. However in some selected patients renal tomography should be performed to confirm and evaluate the presence and size of residual stone fragments.

Abdominal radiograph and renal ultrasound versus excretory urography in the evaluation of asymptomatic patients after extracorporeal shock wave lithotripsy

A prospective study was done to compare the relative efficacy of an abdominal radiograph and renal ultrasound to excretory urography for the evaluation of asymptomatic patients 1 month after extracorporeal shock wave lithotripsy. We evaluated 101 renal units in 84 asymptomatic patients who had undergone extracorporeal shock wave lithotripsy 1 month previously with abdominal radiography, excretory urography and ultrasonography to evaluate the presence of retained stone fragments, dilatation of the collecting system and intrarenal or perirenal fluid collections or masses. The combination of abdominal radiography and ultrasonography identified retained fragments in 62 renal units, while excretory urography identified them in 54. Ultrasonography was less specific in identifying dilatation of part or all of the collecting system; proving falsely positive in 7 renal units and falsely negative in 14 compared to excretory urography. However, the case of obstruction was diagnosed correctly by both modalities. Finally, ultrasound appeared to be more specific and more sensitive in the evaluation of the presence of intrarenal or perirenal abnormalities. We conclude that a combination of abdominal radiography and ultrasonography is as good or better than excretory urography in identifying residual stone fragments and intrarenal or perirenal abnormalities. However, the finding of dilatation of all or part of the collecting system by ultrasonography is nonspecific and probably is better evaluated by excretory urography. We suggest that the routine radiological evaluation of asymptomatic patients 1 month after extracorporeal shock wave lithotripsy could be limited routinely to abdominal radiography and ultrasonography. However, when abnormalities of the collecting system are visualized on these studies excretory urography should be performed.