THE INTRARENAL RESISTIVE INDEX AS A PATHOPHYSIOLOGICAL MARKER OF OBSTRUCTIVE UROPATHY

The Management of Symptomatic Hydronephrosis in Pregnancy

The aim of this article is to provide a literature review on the management of symptomatic physiological hydronephrosis in pregnancy and compare different modalities of intervention when needed. In this review, we conducted an electronic literature search of peer-reviewed journal articles. The PubMed, Research Gate, and Google Scholar databases were queried with the following search terms: "pregnancy", "obstruction," and "hydronephrosis"; the terms "urolithiasis" and "kidney stone" were excluded. As a result, conservative treatment was successful and more favored for most of the patients and the clinicians in the different studies we found. Conservative management will usually include regular analgesia, positioning, and antibiotics. Close follow-up with ultrasound is always recommended. Intervention with ureteric stent insertion or nephrostomy tube insertion was less favored and only triggered by certain clinical criteria. In conclusion, symptomatic hydronephrosis in pregnancy can be safely treated conservatively. However, ureteral double-J stenting or percutaneous nephrostomy are effective and safe treatment methods in the minority of patients with persistent symptoms not responding to conservative management.

Management of urolithiasis in pregnancy

Urolithiasis is the most common cause of nonobstetric abdominal pain, resulting in 1.7 admissions per 1000 deliveries. Urolithiasis most commonly occurs in the second and third trimesters, with an incidence between 1:125 and 1:2000. Acute urinary system obstructions are challenging to manage in obstetric patients because they contribute to physiological and anatomical changes that result in pathological outcomes. The restricted use of computed tomography in diagnosing and managing urolithiasis is particularly challenging. In addition, a prompt diagnosis is required because the presence of renal calculi during pregnancy increases the risk of fulminating sepsis and preterm delivery. Affected pregnancies are conservatively managed; however, 1 in 4 requires surgical intervention. Indications for surgical interventions are complex and range from nephrostomy insertion to empirical stent placement or ureteroscopy. Therefore, a multidisciplinary approach is required to optimize patient care. The diagnosis and management of urolithiasis in pregnancy are complex. We reviewed the role, safety, advantages and disadvantages of diagnostic tests and treatment used to manage acute urinary obstructions in pregnancy.

Ultrasound and color Doppler applications in chronic kidney disease

Chronic kidney disease (CKD) includes all clinical features and complications during the progression of various kidney conditions towards end-stage renal disease (ESRD). These conditions include immune and inflammatory disease such as: primary and hepatitis C virus (HCV)-related glomerulonephritis; infectious disease such as pyelonephritis with or without reflux and tuberculosis; vascular disease such as chronic ischemic nephropathy; hereditary and congenital disease such as polycystic disease and congenital cystic dysplasia; metabolic disease including diabetes and hyperuricemia; and systemic disease (collagen disease, vasculitis, myeloma). During the progression of CKD, ultrasound imaging and color Doppler imaging (US-CDI) can differentiate the etiology of the renal damage in only 50-70% of cases. Indeed, the end-stage kidney appears shrunken, reduced in volume (Ø < 9 cm), unstructured, amorphous, and with acquired cystic degeneration (small and multiple cysts involving the cortex and medulla) or nephrocalcinosis, but there are rare exceptions, such as polycystic kidney disease, diabetic nephropathy, and secondary inflammatory nephropathies. The main difficulties in the differential diagnosis are encountered in multifactorial CKD, which is commonly presented to the nephrologist at stage 4-5, when the kidney is shrunken, unstructured and amorphous. As in acute renal injury and despite the lack of sensitivity, US-CDI is essential for assessing the progression of renal damage and related complications, and for evaluating all conditions that increase the risk of CKD, such as lithiasis, recurrent urinary tract infections, vesicoureteral reflux, polycystic kidney disease and obstructive nephropathy. The timing and frequency of ultrasound scans in CKD patients should be evaluated case by case. In this review, we will consider the morpho-functional features of the kidney in all nephropathies that may lead to progressive CKD.

Ultrasonography of hydronephrosis in the newborn: a practical review

Widespread use of fetal ultrasonography is accompanied by more frequent detection of antenatal hydronephrosis. Therefore, sonographic evaluation of neonates with a history of antenatal hydronephrosis is becoming more widespread. As an initial postnatal non-invasive imaging modality, ultrasonography is used to screen for persistence of hydronephrosis, determine the level and severity of obstruction, and contribute to appropriate diagnosis and treatment. This review aims to provide a practical overview of the sonographic evaluation of neonatal hydronephrosis and to describe the sonographic findings of conditions associated with hydronephrosis in the newborn.

Ultrasound evaluation of obstructive uropathy and its hemodynamic responses in southwest Nigeria

Purpose:

To determine the renal arterial hemodynamic changes induced by obstructive uropathy using Doppler ultrasonography.

Materials and Methods:

60 adult subjects with suspected obstructive uropathy and 60 asymptomatic apparently healthy controls with normal renal ultrasound features were evaluated.

B-mode sonography of the kidneys and spectral Doppler examination of the renal interlobar arteries of all the participants were performed. The mean resistive indices (mRI) of both interlobar arteries were obtained and compared to that of the controls. The mRI of bilaterally obstructed kidneys were also compared with the mRI of unilaterally obstructed kidneys.

Results:

The mRI of the right and left kidneys of subjects were 0.72±0.04 and 0.69±0.06 while those of the controls were 0.64±0.04 and 0.63±0.03 respectively. The mRI for the grades of caliectasis increased from grade I (0.72±0.03) to grade II (0.73±0.03) and grade III (0.73±0.02) but fell within the most severe levels of obstruction (0.69±0.07). There was no statistically significant relationship between the grades of caliectasis and unilateral or bilateral obstruction for both kidneys. The results show a sensitivity and specificity of 86.7% and 90% respectively when mRI≥0.7 was used to determine presence of obstruction.

Conclusion:

Renal duplex sonography is highly sensitive and specific for diagnosis of obstructive uropathy. Increased resistive index of the obstructed kidney may be a useful diagnostic tool in situations where intravenous urography cannot be done or is contraindicated.

[Ultrastructural assessment of the role of dysangiogenesis in congenital hydronephrosis]

OBJECTIVE

To confirm the key role of vascular malformation by ultrasound examination and to make a more detailed study of the manifestations of dysnephro- and angiogenesis.

SUBJECTS AND METHODS

The study enrolled 34 children aged 3 days to 7 years with congenital hydronephrosis, who were divided into 3 groups in accordance with the degree of renal hemodynamic disorders, the criterion for which was a resistive index (RI).

RESULTS

The performed electron microscopic study revealed the signs of malformed vessels of all diameters, as well as hypoplastic changes in the renal parenchyma in children of all ages in all the groups. The most significant ultrastructural signs demonstrating a close correlation between dysangio- and dysnephrogenetic processes are the uniformity of structural failure in the glomerular and arteriolar basement membrane, which shows up in the irregularity of its thickness and obliteration of its layers, as well as the immaturity of endothelial cells of both glomerular and arteriolar capillaries (large sizes and a round shape). The important factor confirming their relationship is a direct correlation between the increased RI in all branches of the renal artery as hypoplastic changes progress in the parenchyma of hydronephrotic kidneys.

CONCLUSION

The investigation demonstrated the interdependence of dysangio- and dysnephrotic processes in children with congenital hydronephrosis.

The relationship between renal resistive index, arterial stiffness, and atherosclerotic burden: the link between macrocirculation and microcirculation

The renal resistive index (RRI) measured by Doppler sonography is a marker of microvascular status that can be generalized to the whole of the arterial tree. Its association with large-vessel dysfunction, such as arterial stiffness or the atherosclerotic burden, can help to establish physiopathological associations between macrocirculation and microcirculation. The authors conducted a cross-sectional study of hypertensive patients (n=202) and a healthy control group (n=16). Stiffness parameters, atherosclerotic burden, and determination of the RRI in both kidneys were performed. The average RRI was 0.69±0.08 and was significantly greater in patients with diabetes and chronic kidney disease. Renal resistive index positively correlated with age, creatinine, and albuminuria. Positive correlations were found with arterial stiffness parameters (pulse wave velocity, ambulatory arterial stiffness index, and 24-hour pulse pressure), as well as atherosclerotic burden and endothelial dysfunction measured as asymmetric dimethylarginine in serum. In the multivariate analysis, independent factors for increased RRI were age, renal function, 24-hour diastolic blood pressure, and arterial stiffness. The authors concluded that there is an independent association between renal hemodynamics and arterial stiffness. This, together with the atherosclerotic burden and endothelial dysfunction, suggests that there is a physiopathologic relationship between macrovascular and microvascular impairment.

Color Doppler ultrasound (CDU) in the diagnosis of obstructive hydronephrosis in pregnant women

PURPOSE

Color Doppler ultrasound (CDU) accuracy of kidneys and bladder in the diagnosis and treatment of hydronephrosis and/or renal colic in pregnancies was evaluated.

METHODS

Between January 2010 and September 2012, 234 pregnant women asymptomatic in 204 cases and with unilateral renal colic in 30 (median 26 years) were evaluated. A CDU of the urinary tract was performed using a sonograph GE Logiq 500 PRO with a multifrequency (3-5 MHz) convex probe. The following parameters were evaluated: resistive index (RI) of the arciform arteries of both kidneys and bilateral ureteric jets. A renal RI > 0.70 and/or a 10 % difference between the kidneys and an asymmetric and/or reduced ureteric jet from the ureteric orifices were considered as diagnostic of obstructive uropathy.

RESULTS

Overall incidence of hydronephrosis was equal to 27 % (63 out 234 cases); the incidence of hydronephrosis, RI > 0.70 and abnormal ureteric jet in asymptomatic vs symptomatic pregnant women was equal to 30.9 vs 50 %, 16.1 vs 50 %, 3 vs 60 % (p < 0.05), respectively. In the 63 pregnancies with asymptomatic hydronephrosis RI and ureteric jet evaluation were abnormal in 39 (19.1 %) and 6 cases (3 %), respectively. In the 30 pregnancies with renal colic conventional ultrasound vs CDU, findings were abnormal in 15 (50 %) vs 20 (66.7 %) (p = 0.015) cases, respectively.

CONCLUSIONS

Color Doppler ultrasound in pregnancies with hydronephrosis and/or renal colic improves conventional ultrasound accuracy; in fact, CDU adds a functional evaluation of the urinary tract when combined with clinical findings allows performing the appropriate management.

The renal resistive index as a predictor of acute hydronephrosis in patients with renal colic

INTRODUCTION

The objective of this study was to determine whether the renal resistive index (RI) can predict hydronephrosis in patients with renal colic (RC) and whether or not its performance is time-dependent.

MATERIALS AND METHODS

The study population was composed of 54 patients admitted for unilateral RC. At the time of the first observation (time point I, tpI), each patient underwent routine examinations, abdominal ultrasonography, and renal color Doppler ultrasound (CDUS) with measurement of the RI. The two imaging studies were repeated 6, 12, 18, 24, 36, and 48 h later (tpII, tpIII, tpIV, tpV, tpVI, tpVII). In addition, each patient underwent non-contrast urinary tract CT 48-60 h after admission. A mean renal RI of >0.70 (mRI+) for the symptomatic kidney was considered indicative of obstruction. Patients were retrospectively divided into two groups: those who developed dilatation (group A) and those who did not (group B).

RESULTS

A mRI+ on CDUS predicted the onset of hydronephrosis with 100% sensitivity, 84% specificity, 92.6% accuracy, PPV and NPV of 87.9% and 100%, and diagnostic efficiency of 84%. In group A, mRI+ were always observed before onset of hydronephrosis in a time-dependent manner. In group B, mRI+ were observed occasionally in 4/25 patients (16%) and all were recorded at tpII. In these cases, the RI had returned to normal by tpIII.

CONCLUSIONS

In our RC patients, renal RI obtained with CDUS predicted the onset of acute dilatation with higher sensitivity, specificity, accuracy, and diagnostic efficiency than ultrasonography, and it can be used routinely in the emergency department to supplement ultrasound findings.

[Experimental study with Doppler ultrasound in partial chronic obstructive uropathy]

INTRODUCTION

This study has aimed to assess the hemodynamic parameters, Renal Resistive Index (RI), Peak Systolic Velocity (PSV), End-Diastolic Velocity (EDV) and Blood Flow of the Renal Artery (FR) by Doppler Ultrasound for diagnosis and monitoring postsurgical partial chronic obstructive uropathy.

MATERIAL AND METHODS

Fifty pigs were used. The experiment was divided into three phases. Phase I consisted of a duplex-Doppler evaluation of the both kidneys to determine the parameters under study. The ratio of each index is calculated as the difference between the value of study kidney and the contralateral. After, a fluoroscopic examination was performed by compressive cystography, excretory urography and retrograde ureteropyelography. Finally, a model of partial right ureteral obstruction was created. After six weeks of the obstructive model, Phase II was begun with the diagnosis of the uropathy, by means of the aforementioned diagnostic methods and the endourological treatment was completed. Phase III is a follow-up performed at 6 months of treatment using the same methods as in the previous phases.

RESULTS

Of the parameters studied, the EDV and its ratio showed greater sensitivity and specificity as a diagnostic marker of obstructive uropathy. In the postoperative monitoring, it was observed that the RI and the EDV returned to baseline levels, with the baseline values.

CONCLUSIONS

The ΔEDV and its ratio is the parameter that shows the greater efficacy for the diagnosis of chronic partial obstructive uropathy, however, it is insufficient to avoid conventional diagnostic techniques. All the parameters, mainly the EDV, have proven useful as complementary tests for monitoring after endourologic resolution of obstructive uropathy.

Biomarkers for pediatric urological disease

PURPOSE OF REVIEW

New disease-specific biomarkers are sorely needed within all fields of medicine. This review covers the current literature of biomarkers within pediatric urology and discusses future perspectives and directions for biomarker discovery.

RECENT FINDINGS

Biomarkers can be used to diagnose disease, monitor response, or sub-classify disease. Within pediatric urology, numerous markers for renal obstruction [ureteropelvic junction (UPJ)] and vesicoureteral reflux (VUR) have been identified and have shown initial promise; however, no markers have been rigorously validated or demonstrated to be clinically effective. Recent advances in proteomic technologies may provide a new discovery method to identify panels of markers for specific disease.

SUMMARY

New clinically significant biomarkers of UPJ or VUR that can improve the diagnostic capability or help determine risk for renal damage are sorely needed. However, rigorous clinical validation of previously identified markers has been limited. Other studies have demonstrated that combining various markers may help improve the ability to define clinical relevance. To improve biomarker discovery efforts, a combination of focused biomarker studies, potentially using new advanced proteomic technologies, and well designed clinical studies are needed.

Prospective evaluation of the alterations in the morphology and vascular resistance of the renal parenchyma with color Doppler ultrasonography after percutaneous nephrolithotomy

PURPOSE

To evaluate the kidneys with color Doppler ultrasonography (CDUS) to determine whether percutaneous nephrolithotomy (PNL) causes renal parenchymal damage.

PATIENTS AND METHODS

In 24 patients who underwent unilateral PNL with single renal pole access, cortical thickness, echogenicity, and resistive index (RI) were measured in each pole of the operated and contralateral kidney separately before and at postoperative day (POD) 1, and at 3, 6, and 12 months after PNL.

RESULTS

The mean age of the patients was 36.67 +/- 14.68 years. The serum creatinine level increased significantly immediately after PNL but diminished to the preoperative level at POD 1. Changes in serum blood urea nitrogen and electrolyte levels were insignificant. Mean cortical thickness increased significantly in the access pole and contralateral kidney and insignificantly in the nonaffected pole. No statistically significant change was recorded in parenchymal echogenicitiy. Statistically significant differences in cortical thickness between the access pole and the contralateral kidney and between the nonaffected pole and the contralateral kidney disappeared 3 months later. Differences in mean cortical thickness between the access pole and the nonaffected pole were insignificant at all examination periods. Echogenicity was greater in the access pole and the nonaffected pole than in the contralateral kidney only at POD 1. No significant difference was noted in the echogenicity between the access pole and the nonaffected pole. Mean RIs were lower than the universally accepted pathologic RI level (0.70) at all periods. There was no statistically significant difference between the mean RI values of the access pole, nonaffected pole, and contralateral kidney.

CONCLUSION

PNL does not cause obvious renal dysfunction and significant parenchymal scarring, which is indicated by the decrease in cortical thickness and increases in cortical echogenicity and intrarenal RI.

A novel quantitative method for measuring obstruction in the upper urinary tract: the 'obstruction coefficient'

OBJECTIVES

To define an exact pressure-flow correlation in the upper urinary tract using an improved measurement method, to quantitatively characterize the degree of postrenal obstruction and to find a simple way of calculating it in everyday urological practice.

METHODS

The data of 112 cases were included in the analysis. The dynamic method of a multistep, constant pressure perfusion study was used to precisely measure a wide range of pressure-flow dependences. Values of established parameters measuring the degree of obstruction were compared: the intrapelvic pressure, the ureteral opening pressure and the newly introduced 'obstruction coefficient'.

RESULTS

Pressure-flow relations can be best presented by a parabolic curve described by the simple formula Y = AX(2) + B. Depending on the degree of obstruction, the shape of this curve can be characterized by a single number, that we defined as the 'obstruction coefficient'. Computer-based evaluation software for the easy calculation of this coefficient is presented here and freely available on demand. The Whitaker-test, the ureteral opening pressure, and the 'obstruction coefficient' showed significant correlation proving that the latter was clinically applicable in measuring the degree of obstruction.

CONCLUSION

Calculation of the 'obstruction coefficient' enables us to exactly define the degree of upper urinary tract obstruction and to safely monitor for a long period conditions inhibiting ureteric passage.

Role of resistive index in renal colic

We studied the role of duplex Doppler ultrasonography in the diagnosis of renal obstruction caused by ureteral calculi. Using duplex Doppler sonography, we evaluated the intrarenal hemodynamics of 27 patients who presented to the emergency department with renal colic. We performed Doppler ultrasonography on patients in whom US did not reveal any pathology causing renal colic and calculated and compared mean RI values of normal and obstructed kidneys and DeltaRI values of each group. Threshold levels for the diagnosis of urinary tract obstruction (mean RI > or = 0.70 and DeltaRI > or = 0.08) were used to determine the sensitivity and specificity of Doppler sonography for the diagnosis of urinary tract obstruction. Patients were investigated for revealing calculi diagnosis either by stone excretion history, intravenous pyelography or non contrast enhanced urinary computed tomography. A total of 162 intrarenal arterial Doppler recordings were made on 54 kidneys. Of the 16 patients with urinary obstruction, 11 (68%) had sonographic evidence of pelvicalyceal dilatation. The mean RI of the 16 obstructed and 11 unobstructed kidneys was 0.69 +/- 0.04 and 0.61 +/- 0.06 (mean +/- standard deviation), respectively. The difference between the mean RI values for each group was statistically significant (P < 0.05). Mean RI values of the contralateral kidneys in the obstructed group and unobstructed group were 0.61 +/- 0.03 and 0.59 +/- 0.05, respectively. Also DeltaRI value (0.07 +/- 0.02) of obstructed kidney group was statistically higher than the DeltaRI value (0.01 +/- 0.03) of the unobstructed group (P < 0.05). The mean RI of the 16 obstructed kidneys (0.69 +/- 0.04) was significantly greater than that of the 16 unobstructed contralateral kidneys (0.61 +/- 0.03) (P < 0.05). This study supplements the existing evidence that, in acutely obstructed kidneys, renal Doppler recording can demonstrate altered renal perfusion before pelvicalyceal system dilatation and distinguish obstructed and unobstructed kidneys evaluated with suspicion of renal colic.

[Usefulness of renal resistive index in the diagnosis and evolution of the obstructive uropathy. Experimental study]

OBJECTIVE

The study was focused on determining the effectiveness and reliability of using the renal resistance index as a method of diagnosing and monitoring the evolution of obstructive uropathy treatment. For this purpose, we conducted an experimental study on a homogenous group of animals that all had the same level of obstruction.

MATERIAL AND METHODS

15 healthy female pigs were used. The experiment was divided into three phases: phase I consisted of a study prior to unilateral pyeloureteral junction obstruction, performing retrograde ureteropyelography, renal B-mode ultrasound and duplex-Doppler (of both kidneys) at a level of the arcuate arteries. Then, the obstruction was performed on the animals. Phase II commenced by diagnosing the lesion, 6 weeks after the previous phase, by means of the aforementioned diagnostic methods. Finally, the endourological treatment was completed. Animals were monitored (Phase III) 15 weeks after the endopyelotomy, using the same methods as in the study, by assessing the urinary tract (fluoroscopy) and both kidneys by determining the renal resistance index and ratio.

RESULTS

All the animals in the study showed signs of urinary obstruction on radiology and renal ultrasound 6 weeks after ureteral ligature. After treatment and follow-up, all animals showed signs of having recovered from the obstructive uropathy. Values of deltaRI during the 3 phases are detailed below. Fase I deltaIR = 0.01, Fase II deltaIR = 0.11, Fase III deltaIR = 0.02.

CONCLUSION

RI determination using duplex-Doppler is effective for distinguishing obstructive dilatation using non-invasive techniques. However, this parameter provides very slight differences and it can also be influenced by too many direct and indirect factors (observational, patient age, anaesthesia, haemodynamic parameters, etc.), to supplant the classic diagnostic methods.

Renal arterial resistance in septic shock: effects of increasing mean arterial pressure with norepinephrine on the renal resistive index assessed with Doppler ultrasonography

OBJECTIVE

To determine the effects of increasing mean arterial pressure (MAP) on renal resistances assessed by Doppler ultrasonography in septic shock.

DESIGN AND SETTING

Prospective, single-center, nonrandomized, open-label trial in the surgical intensive care unit in a university teaching hospital.

PATIENTS AND PARTICIPANTS

11 patients with septic shock who required fluid resuscitation and norepinephrine to increase and maintain MAP at or above 65 mmHg.

INTERVENTIONS

Norepinephrine was titrated in 11 patients in septic shock during three consecutive not randomized periods of 2 h to achieve a MAP at successively 65, 75, and 85 mmHg.

MEASUREMENTS AND RESULTS

At the end of each period hemodynamic parameters and renal function variables (urinary output, creatinine, clearance) were measured, and Doppler ultrasonography was performed on interlobar arteries to assess the renal resistive index. When increasing MAP from 65 to 75 mmHg, urinary output increased significantly from 76 +/- 64 to 93 +/- 68 ml/h and the resistive index significantly decreased from 0.75 +/- 0.07 to 0.71 +/- 0.06. No difference was found between 75 and 85 mmHg.

CONCLUSIONS

Doppler ultrasonography and resistive index measurements may help determine in each patient the optimal MAP for renal blood flow and may be a relevant end-point to titrate the hemodynamic treatment in septic shock.

Clinical utility of ureteral jets: disparate opinions

BACKGROUND AND PURPOSE

Many renal/bladder ultrasound scans at our institution include evaluation of ureteral jets, often regardless of the indication for the study. Such jets often are absent in normal volunteers. Because these jets are of unclear clinical significance, we sought to determine if urologists and radiologists nationally agree on the clinical utility of ureteral jets.

MATERIALS AND METHODS

A three-item survey was mailed electronically to a randomly selected group of urologists and radiologists asking about the physician's practice pattern and opinion of the clinical relevance of ureteral jets by percentage and on the Likert scale. Using the unpaired Student's t-test, the responses of the groups were compared.

RESULTS

Responses were available from 177 physicians. Statistically significant differences were noted between urologists and radiologists for all three questions. Radiologists reported that 50% of ultrasonograms evaluate ureteral jets, compared with 29% for urologists (P < 0.01). Whereas radiologists "somewhat agreed" (2.01) that ureteral jets were clinically relevant, urologists were "indifferent" (2.77) to their clinical relevance (P < 0.01). The two groups also differed on the question of whether a routine ultrasound study should include evaluation of ureteral jets.

CONCLUSIONS

Urologists and radiologists disagreed on both the necessity for evaluating ureteral jets and their clinical relevance. On the basis of jet frequency and a review of the literature, accurate evaluation of jets requires a minimum of 10 minutes. The cost of this time should be considered in light of the requesting physician's opinion of the clinical relevance of the results. Until further evidence supports their value, evaluation of jets should be excluded from routine renal/bladder sonography.

Long-term effects of percutaneous nephrolithotomy on renal morphology and arterial vascular resistance as evaluated by color Doppler ultrasonography: preliminary report

We evaluated the long-term effects of percutaneous nephrolithotomy (PNL) on renal morphology and vascular resistance. Parenchyma thickness, echogenicity and resistive index (RI) of upper, middle and lower poles of operated and contralateral kidneys of 41 patients with 82 renal units who underwent unilateral PNL with single pole access between 2000 and 2002 were examined separately by color Doppler ultrasonography. Mean patient age and duration between PNL and evaluation time were 38.29+/-11.53 years and 46.44+/-10.9 months, respectively. In operated kidney, mean RI, parenchyma thickness and echogenicity of the access pole were not statistically different than those of the adjacent two poles (0.608+/-0.053 vs. 0.608+/-0.052 for RI, P=0.895; 11.46+/-2.58 vs. 11.41+/-2.68 mm for parenchyma thickness, P=0.838; 0.049+/-0.31 vs. 0.073+/-0.33 for parenchyma echogenicity, P=0.160, respectively). Although mean RI and parenchyma thickness of access pole were statistically significantly different than the mean values of contralateral kidney (0.562+/-0.032 and 14.31+/-1.37 mm, respectively), no statistical difference was found between mean parenchyma echogenicities of both of them (echogenicity of contralateral kidney was 0, P=0.317). No significant difference was found between the average echogenicities of the three poles of the operated and contralateral kidneys (0.063+/-0.32 vs. 0, P=0.080). In 14 patients RI decreased from 0.694+/-0.058 to 0.602+/-0.056 in operated kidney (P=0.001) and from 0.604+/-0.06 to 0.559+/-0.031 in contralateral kidney (P=0.018) following PNL. It seems that PNL does not cause renal scarring, renal parenchymal loss or increase in renal vascular resistance in the long term. However, prospective studies must be performed for more definitive conclusions.

Contribution of the renin-angiotensin system to the intrarenal resistive index in chronic unilateral partial ureteral obstruction in dogs

PURPOSE

We investigated the role of the renin-angiotensin system on intrarenal hemodynamics in chronic unilateral partial ureteral obstruction (UPUO) using Doppler ultrasound (US).

METHODS

In 11 dogs with chronic UPUO, we determined the renal resistive index (RI) before and 1 h after the intravenous infusion of an angiotensin-converting enzyme (ACE) inhibitor (captopril), an angiotensin II receptor type 1 (ART1) antagonist (L-158,809), and the combination of these two drugs. Change in resistive index (ΔRI) was calculated as RI after the administration of each tested material minus baseline RI.

RESULTS

At the baseline measurement, significant differences in RI were seen between obstructed and nonobstructed kidneys. ACE inhibitor, ART1 antagonist, or the combination of these drugs did not result in any significant changes in RI in either obstructed or nonobstructed kidneys. However, in obstructed kidneys, ΔRI in the combination of ACE inhibitor and ART1 antagonist were significantly greater than those in ACE inhibitor or ART1 antagonist alone, whereas there were no significant differences in those values in nonobstructed kidneys.

CONCLUSION

These observations suggest that the renin-angiotensin system in dogs with chronic UPUO may not contribute significantly to the differences in intrarenal RI between obstructed and nonobstructed kidneys. However, the angiotensin-producing pathways and angiotensin II receptor subtypes other than ACE and ART1 may have some different effects between obstructed and nonobstructed kidneys.

Functional evaluation of the urinary tract by color-Doppler ultrasonography (CDU) in 100 patients with renal colic

INTRODUCTION AND OBJECTIVE

To evaluate if the addition of a renal color-Doppler ultrasonography (CDU) in the setting of acute renal colic improves the sensitivity of conventional sonography.

MATERIALS AND METHODS

Between July 2002 and June 2003, 100 patients (median 49 years) with renal colic have been evaluated. Within 24 h of the admission, a CDU study of the urinary tract was performed using a sonograph GE Logiq 500 PRO with a multifrequency (3-5 MHz) convex probe. The following parameters were evaluated: ultrasonography (US) of both kidneys, ureters and bladder; resistive index (RI) of the arciform arteries of both kidneys in three different parenchymal areas; ureteric jets in response to hydration. A renal RI>0.70 and/or a 10% difference between the kidneys were considered as diagnostic of obstructive uropathy; an asymmetric and/or reduced ureteric jet from the ureteric orifices was an additional indicator of obstruction. All patients underwent a CT scan both with and without the administration of contrast medium.

RESULTS

Enhanced helical CT demonstrated an urinary stone in 90 out of the 100 patients (90%): 29 pyelic, 28 at the pyelo-ureteral junction, 23 lumbo-iliac and 10 juxtavesical stones. Among 90 patients with urolithiasis, the stone was undetectable with US in 11 cases (12.2%); in 8 cases (8.9%) pyelocalicectasis was absent, and in 6 patients (6.6%) a non-obstructive hydronephrosis was present. Median RI in obstructed and non-obstructed kidney was 0.73 (range 0.71-0.87) versus 0.62 (0.50-0.68), respectively; in two, obstructed kidneys RI was <0.70 but greater than 10% compared with normal side. Sensitivity and specificity of US, CDU (RI+ureteric jet), unenhanced helical CT and CDU in association with unenhanced helical CT were 94.8 and 55.5, 98.9 and 90.9, 100 and 100%, respectively.

DISCUSSION AND CONCLUSIONS

CDU in patients with renal colic and/or pelvicalicectasis improves the diagnostic accuracy of US in distinguishing between obstructive and non-obstructive dilatation. Combined with unenhanced CT, CDU has a 100% sensitivity and specificity. Moreover, due to the absence of contraindications and side-effects, CDU is indicated for the follow-up of patients after ESWL, pregnant women and children.

BIOMARKERS OF CONGENITAL OBSTRUCTIVE NEPHROPATHY: PAST, PRESENT AND FUTURE

PURPOSE

Congenital obstructive nephropathy constitutes one of the major causes of renal insufficiency in infants and children. This review addresses the need to define biomarkers that serve as surrogate end points for measuring the severity of obstruction, the evolution of renal maldevelopment and injury, and the response to medical or surgical intervention.

MATERIALS AND METHODS

The literature from the last 10 years was reviewed for biomarkers of congenital obstructive nephropathy. Sources of biomarkers included urine, blood, amniotic fluid, tissue and imaging techniques.

RESULTS

Previous markers of congenital obstructive nephropathy include sonographic renal pelvic diameter, quantitative diuretic renography, and markers of glomerular and tubular function. Attempts to correlate renal histological changes with differential renal function have been disappointing. Immunohistochemical analysis and laser capture microscopy should improve specificity. Most promising is the application of new insights into the cellular response of the developing kidney to urinary tract obstruction. These findings include components of the renin-angiotensin system, transforming growth factor-beta 1, monocyte chemoattractant protein-1 and epidermal growth factor. Microarray studies show unique patterns of gene expression by the neonatal rat kidney subjected to ureteral obstruction, and proteomics should provide even more sensitive biomarkers of obstructive nephropathy.

CONCLUSIONS

We must define the cellular and molecular bases of renal maldevelopment, focusing on the link between functional and developmental pathophysiology. These findings will lead to biomarkers that will optimize our management of congenital obstructive nephropathy.

[Urinary obstruction]

Obstructive uropathy is a result of the particular tubular configuration of the urinary tract and involves virtually all its organs. This review analyses upper urinary tract obstructions as well as a number of lower urinary tract conditions whenever the circumstances of the urological disease progress so advises it. A comprehensive exposition is made of the different types of obstruction, the basic pathophysiological principles and the respective anatomical transposition. The pathophysiological features characterising intrauterine obstructions, obstructions occurring during pregnancy and in the elderly are also highlighted. Finally an updated analysis is made of the diagnostic contribution made by all techniques susceptible to be used when dealing with obstructive uropathies highlighting the prognostic relevance of early diagnosis and treatment. The hope placed in the use of modern techniques to establish a differential diagnosis of chronic obstructive uropathy is also emphasised.

Diuretic Doppler ultrasonography in chronic unilateral partial ureteric obstruction in dogs

OBJECTIVE

To compare the effects of diuresis induced by a loop diuretic (frusemide), an osmotic diuretic (mannitol) and a high-osmolar radio-contrast medium (sodium iothalamate) on the intrarenal resistive index (RI) in dogs with chronic unilateral partial ureteric obstruction (UPUO).

MATERIALS AND METHODS

The split renal clearance and intrarenal RI were estimated in 11 dogs with chronic UPUO. Doppler ultrasonography measurements of the interlobar arteries were obtained before and 10 min after the intravenous infusion of 1 mg/kg frusemide, 1 g/kg mannitol or 20 mL 60% sodium iothalamate. The same experimental protocol was repeated with another drug at 1-week intervals.

RESULTS

There was a significant difference between the intrarenal RI of obstructed and unobstructed kidneys in the chronic phase of UPUO. While mannitol and sodium iothalamate significantly increased the RI in both kidneys, differences in RI between the kidneys decreased after infusing the two drugs. However, while frusemide insignificantly increased the RI in the obstructed kidney, it decreased the RI in unobstructed one. Consequently, the difference in RI between the kidneys increased significantly after administering frusemide. There were no significant differences in urinary volume after administering each of the drugs.

CONCLUSIONS

As there were no significant differences in the diuretic effects of the drugs, frusemide may have additional effects on the RI of unobstructed kidneys other than diuresis. Frusemide increased the difference between the intrarenal RI of the kidneys and therefore may improve the detection of unilateral urinary obstruction in humans.