Ultrasound evaluation of access complications: Thrombosis, aneurysms, pseudoaneurysms and infections.

Arteriovenous fistula (AVF) complications are classified based on fistula outcomes. This review aims to update colour Doppler (CD) and pulse wave Doppler (PWD) roles in managing early and late complications of the native and prosthetic AVF. Vascular access (VA) failure occurs because inflow or outflow stenosis activates Wirchow's triad inducing thrombosis. Therefore, the diagnosis of the tributary artery and outgoing vein stenosis will be the first topic considered. Post-implantation complications occur from the inability to achieve AVF maturation and dialysis suitability due to inflow/outflow stenosis. Late stenosis is usually a sequence of early defects repaired to maintain patency. Less frequently, in the mature AVF or graft, complications are acquired 'de novo'. They derive either from incorrect management of vascular access (haematoma, pseudoaneurysm, prosthesis infection) or wall pathologies (aneurysm, myxoid valve degeneration, kinking, coiling, abnormal dilation from defects of elastic structures). High-resolution transducers (10-20 MHz) allow the characterization of the wall damage, haemodynamic dysfunctions, early and late complications even if phlebography remains the gold standard for the diagnosis for its sensitivity and specificity.

Basics for performing a high-quality color Doppler sonography of the vascular access.

In the last years, the systematic use of ultrasound mapping of the upper limb vascular network before the arteriovenous fistula (AVF) implantation, access maturation, and clinical management of late complications is widespread and expanding. Therefore, a good knowledge of theoretical outlines, instrumentation, and operative settings is undoubtedly required for a thorough examination. In this review, the essential Doppler parameters, B-Mode setting, and Doppler applications are considered. Basic concepts on the Doppler shift equation, angle correction, settings on pulse repetition frequency, operative Doppler frequency, gain are reported to ensure adequate and correct sampling of blood flow velocity. A brief analysis of the Doppler inherent artefacts (as random noise, blooming, aliasing, and motion artefacts) and the adjustment setting to minimize or eliminate the confounding artefacts are also considered. Doppler aliasing occurs when the pulse repetition frequency is set too low. This artefact is particularly frequent in vascular access sampling due to the high velocities range registered in the fistula's different segments. Aliasing should be recognized because its correction is crucial to analyse the Doppler signals correctly. Recent advances in instrumentation are also considered about a potential purchase of a portable ultrasound machine or a top-of-line, high-end, or mid-range ultrasound system. Last, the pulse wave Doppler setting for vascular access B-Mode and Doppler assessment is summarized.

Preoperative psychological characteristics affecting mid-term outcome after bariatric surgery: a follow-up study.

BACKGROUND: The purpose of this study was to investigate the relationship between preoperative psychological factors and percentage of total weight loss (%TWL) after laparoscopic Roux-en-Y gastric bypass (LRYGB) to identify possible psychological therapy targets to improve the outcome of bariatric surgery. METHODS: Seventy-six patients completed the Hamilton's Anxiety and Depression Scales (HAM-A, HAM-D) and Toronto Alexithymia Scale (TAS-20) the day before surgery (T0). The pre-operative body weight and the %TWL at 3 (T1), 6 (T2), and 24-30 (T3) months were collected. RESULTS: At T3, depressed and alexithymic patients showed a lower %TWL compared to non-depressed patients (p = 0.03) and to non-alexithymic patients (p = 0.02), respectively. Finally, patients who had at least one of the three analyzed psychological factors showed less weight loss, at T2 (p = 0.02) and T3 (p = 0.0004). CONCLUSIONS: Psychological factors may also affect long-term outcome of bariatric surgery. This study shows an association between alexithymia/depression pre-operative levels and the weight loss at 30 months'follow-up after bariatric surgery. LEVEL OF EVIDENCE: Level III, longitudinal cohort study.

The influence of preoperative psychological factors on weight loss after bariatric surgery: A preliminary report.

Aim of this study was to investigate relationship between preoperative psychological factors and % total weight loss after gastric bypass. 76 adult patients scheduled for bariatric surgery were preoperatively asked to complete anxiety and depression Hamilton scales and Toronto Alexithymia Scale. At 3- and 6-month follow-up, body weight was assessed. At 6-month follow-up, alexithymic patients showed a poorer % total weight loss compared with non-alexithymic patients ( p = .017), and moderately depressed patients showed a lower % total weight loss compared with non-depressed patients ( p = .011). Focused pre- and postoperative psychological support could be useful in bariatric patients in order to improve surgical outcome.

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.

Standardized Protocol for Hemodialysis Vascular Access Assessment: The Role of Ultrasound and ColorDoppler.

INTRODUCTION: Ultrasound and colorDoppler technique, which is relatively inexpensive, rapid, non-invasive and repeatable is a powerful tool used for early diagnosis of vascular access (VA) complications in hemodialysis patients. To date a standard and widely comprehensible echocolorDoppler (ECD) protocol is not available. MATERIALS AND METHODS: A simple step-by-step protocol based on anatomical and hemodynamic parameters of VA has been developed during a 3-years VA ECD follow-up. It consists of an ECD study scheme. The algorithm created involves the calculation of brachial artery flow, description of artero-venous and/or graft-vascular anastomosis and efferent vessel and/or graft. RESULTS: The algorithm allows to formulate a medical report that takes into account both anatomic and hemodynamic parameters of the VA. Reduction of complications and the prevention of chronic complications as well as the early detection of acute problems were achieved. DISCUSSION AND CONCLUSION: The creation of a step-by-step protocol may simplify the multidisciplinary management of VA, its monitoring and the early diagnosis of its complications.

[The Retroperitoneal space]. / Il Retroperitoneo questo sconosciuto.

We describe the case of a 45-year-old woman with a clinical history of breast cancer presenting with anuric renal failure, metabolic acidosis and bilateral grade 2-3 hydronephrosis. Following insertion of bilateral ureteral stents, urinary output was 5000 ml in the subsequent 24 hours with frankly bloody urine, after which anuria recurred. A new ultrasound examination showed hydronephrotic kidneys with properly positioned stents, a distended bladder free of clots and a hypo-anechoic, well-demarcated mass enveloping the aorta. With the echo color Doppler, injection of saline solution through a Foley catheter showed fluid flow similar to a ureteral jet within the bladder. Since the catheter balloon could not be sonographically visualized in the bladder we decided to re-examine this organ. Scans over what we thought was the bladder detected the balloon in a depleted bladder and fluid underlying it. CT urography revealed bilateral hydronephrosis secondary to a reperitoneal fibrous plaque surrounding the ureters and extending to the pelvic floor that had produced an encapsulated fluid collection. The clinical and imaging findings were strongly suggestive of acute obstructive renal failure secondary to retroperitoneal fibrosis. The retroperitoneal fluid collection, which had been mistaken for the bladder, may be due to a hematoma, aurinoma, an inflammatory process or a lymphocele.

Ultrasound findings of BK polyomavirus-associated nephropathy in renal transplant patients.

BK polyomavirus (BKV) is an emerging pathogen in immunocompromised patients. BKV infection occurs in 1-9 % of renal transplants and causes chronic nephropathy or graft loss. Diagnosis of BKV-associated nephropathy (BKVAN) is based on detection of viruria then viremia and at least a tubule-interstitial nephritis at renal biopsy. This paper describes the ultrasound and color Doppler (US-CD) features of BKVAN. Seventeen patients affected by BKVAN were studied using a linear bandwidth 7-12 MHz probe. Ultrasound showed a widespread streak-like pattern with alternating normal echoic and hypoechoic streaks with irregular edges from the papilla to the cortex. Renal biopsy performed in hypoechoic areas highlighted the typical viral inclusions in tubular epithelial cells. Our experience suggests a possible role for US-CD in the non-invasive diagnosis of BKVAN when combined with blood and urine screening tests. US-CD must be performed with a high-frequency linear probe to highlight the streak-like pattern of the renal parenchyma.

Intra-Parenchymal Renal Resistive Index Variation (IRRIV) Describes Renal Functional Reserve (RFR): Pilot Study in Healthy Volunteers.

An increase of glomerular filtration rate after protein load represents renal functional reserve (RFR) and is due to afferent arteriolar vasodilation. Lack of RFR may be a risk factor for acute kidney injury (AKI), but is cumbersome to measure. We sought to develop a non-invasive, bedside method that would indirectly measure RFR. Mechanical abdominal pressure, through compression of renal vessels, decreases blood flow and activates the auto-regulatory mechanism which can be measured by a fall in renal resistive index (RRI). The study aims at elucidating the relationship between intra-parenchymal renal resistive index variation (IRRIV) during abdominal pressure and RFR. In healthy volunteers, pressure was applied by a weight on the abdomen (fluid-bag 10% of subject's body weight) while RFR was measured through a protein loading test. We recorded RRI in an interlobular artery after application of pressure using ultrasound. The maximum percentage reduction of RRI from baseline was compared in the same subject to RFR. We enrolled 14 male and 16 female subjects (mean age 38 ± 14 years). Mean creatinine clearance was 106.2 ± 16.4 ml/min/1.73 m(2). RFR ranged between -1.9 and 59.7 with a mean value of 28.9 ± 13.1 ml/min/1.73 m(2). Mean baseline RRI was 0.61 ± 0.05, compared to 0.49 ± 0.06 during abdominal pressure; IRRIV was 19.6 ± 6.7%, ranging between 3.1% and 29.2%. Pearson's coefficient between RFR and IRRIV was 74.16% (p < 0.001). Our data show the correlation between IRRIV and RFR. Our results can lead to the development of a "stress test" for a rapid screen of RFR to establish renal susceptibility to different exposures and the consequent risk for AKI.

Clinical Scenarios in Chronic Kidney Disease: Parenchymal Chronic Renal Diseases - Part 1.

In diabetes, kidneys' morphological changes are non-specific at ultrasound (US) and they vary according to disease stage. In the earlier stages, kidneys are enlarged and diffusely hypoechoic due to hyperfiltration. Kidneys size decreases only in advanced stages whereas renal cortical echogenicity progressively increases due to glomerulosclerosis. Nephromegaly, as well as discrepancy between size and renal function, are typical features of diabetic nephropathy either in early or in advanced stages of the disease. Resistive indexes progressively increase together with serum creatinine levels and macro/microcirculation damage. Chronic glomerulonephritis (CGN) is the third leading cause of chronic kidney disease and it represents the clinical evolution of a variety of primary or secondary glomerular diseases. Kidneys in CGN are gradually reduced in volume, but remain symmetric, easily recognizable in renal space until the disease's later stages.

Clinical Scenarios in Chronic Kidney Disease: Cystic Renal Diseases.

Cysts are frequently found in chronic kidney disease (CKD) and they have a different prognostic significance depending on the clinical context. Simple solitary parenchymal cysts and peripelvic cysts are very common and they have no clinical significance. At US, simple cyst appears as a round anechoic pouch with regular and thin profiles. On the other hand, hereditary polycystic disease is a frequent cause of CKD in children and adults. Autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD) are the best known cystic hereditary diseases. ADPKD and ARPKD show a diffused cystic degeneration with cysts of different diameters derived from tubular epithelium. Medullary cystic disease may be associated with tubular defects, acidosis and lithiasis and can lead to CKD. Acquired cystic kidney disease, finally, is secondary to progressive structural end-stage kidney remodelling and may be associated with renal cell carcinoma.

Clinical Scenarios in Acute Kidney Injury: Hepatorenal Syndrome.

Renal failure commonly occurs in patients affected by cirrhosis, especially when there is ascites. It is typically secondary to intercurrent events that can further compromise blood flow in conditions of relatively decreased renal perfusion. Hepatorenal syndrome (HRS) is a particular and common type of kidney failure that affects patients with liver cirrhosis or, less frequently, with fulminant hepatic failure. The syndrome is characterized by splanchnic vasodilation and renal vasoconstriction. The classification of HRS identifies 2 categories of kidney failure, known as type 1 and type 2 HRS, that occur in patients with either cirrhosis or fulminant hepatic failure.

Clinical Scenarios in Chronic Kidney Disease: Kidneys' Structural Changes in End-Stage Renal Disease.

Acquired cystic kidney disease (ACKD) and renal cell carcinoma (RCC) are the most important manifestations of end-stage kidneys' structural changes. ACKD is caused by kidney damage or scarring and it is characterized by the presence of small, multiple cortical and medullary cysts filled with a fluid similar to preurine. ACKD prevalence varies according to predialysis and dialysis age and its pathogenesis is unknown, although it is stated that progressive destruction of renal tissue induces hypertrophy/compensatory hyperplasia of residual nephrons and may trigger the degenerative process. ACKD is almost asymptomatic, but it can lead to several complications (bleeding, rupture, infections, RCC). Ultrasound (US) is the first level imaging technique in ACKD, because of its sensitivity and reliability. The most serious complication of ACKD is RCC, which is stimulated by the same growth factors and proto-oncogenes that lead to the genesis of cysts. Two different histological types of RCC have been identified: (1) RCC associated with ACKD and (2) papillary renal clear cell carcinoma. Tumors in end-stage kidneys are mainly small, multifocal and bilateral, with a papillary structure and a low degree of malignancy. At US, RCC appears as a small inhomogeneous nodule (<3 cm), clearly outlined from the renal profile and hypoechoic if compared with sclerotic parenchyma. In some cases, tumor appears as a homogeneous and hyperechoic multifocal mass. The most specific US sign of a small tumor in end-stage kidney is the important arterial vascularization, in contrast with renal parenchymal vascular sclerosis.

Clinical Scenarios in Acute Kidney Injury: Parenchymal Acute Kidney Injury-Tubulo-Interstitial Diseases.

Acute tubular necrosis (ATN) is the most common type of acute kidney injury (AKI) related to parenchymal damage (90% of cases). It may be due to a direct kidney injury, such as sepsis, drugs, toxins, contrast media, hemoglobinuria and myoglobinuria, or it may be the consequence of a prolonged systemic ischemic injury. Conventional ultrasound (US) shows enlarged kidneys with hypoechoic pyramids. Increased volume is largely sustained by the increase of anteroposterior diameter, while longitudinal axis usually maintains its normal length. Despite the role of color Doppler in AKI still being debated, many studies demonstrate that renal resistive indexes (RIs) vary on the basis of primary disease. Moreover, several studies assessed that higher RI values are predictive of persistent AKI. Nevertheless, due to the marked heterogeneity among the studies, further investigations focused on timing of RI measurement and test performances are needed. Acute interstitial nephritis is also a frequent cause of AKI, mainly due to non-steroidal anti-inflammatory drugs and antibiotics administration. The development of acute interstitial nephritis is due to an immunological reaction against nephritogenic exogenous antigens, processed by tubular cells. In acute interstitial nephritis, as well as in ATN, conventional US does not allow a definitive diagnosis. Kidneys appear enlarged and widely hyperechoic due to interstitial edema and inflammatory infiltration. Also, in this condition, hemodynamic changes are closely correlated to the severity and the progression of the anatomical damage.

Clinical Scenarios in Acute Kidney Injury-Parenchymal Acute Kidney Injury - Vascular Diseases.

Acute cortical necrosis and hemolytic uremic syndrome (HUS) are 2 clinical scenarios of parenchymal acute kidney injury (AKI) related to renal microvascular injury. Acute cortical necrosis is a rare condition related to an ischemic necrosis of renal cortex. Necrotic lesions can be due to several injuries and may be focal, multifocal or diffuse. Renal necrotic lesions become visible with ultrasound only after renal recovery. HUS is a rare disease characterized by hemolytic anemia, thrombocytopenia and AKI. Color Doppler ultrasound is useful during diagnostic and follow-up phase. Renal artery thrombosis and renal vein thrombosis may also cause parenchymal AKI. Acute renal infarction is a rare pathological condition that occurs due to clots or cholesterol aggregates occluding renal artery or its branches. Several causes may lead to partial or massive kidney ischemic necrosis. Contrast-enhanced CT allows definitive diagnosis in 80% of cases and, at present, it is the first imaging technique used. Ultrasound (US) sensitivity and specificity significantly increases with color Doppler and contrast-enhanced US (CEUS). In AKI patients, in whom the use of iodinated contrast media is contraindicated, color Doppler and CEUS may be valid alternatives for the diagnosis of acute renal infarction. Renal vein thrombosis may be primary or secondary to retroperitoneal neoplasm or inflammatory diseases. It rarely causes an acute worsening of renal function because of the presence of several anastomosis that prevent parenchymal necrosis due to venous congestion. Color Doppler US could detect thrombus within the lumen and document the absence of venous flow.

Clinical Scenarios in Acute Kidney Injury: Post-Renal Acute Kidney Injury.

The incidence of acute kidney injury related to urinary tract obstruction is low (1-10%). It occurs in bilateral renal or lower urinary tract obstruction or in ureter obstruction in patients with a single functioning kidney or with pre-existing chronic kidney disease. The etiology and the incidence of obstruction vary on the basis of age and gender. Conventional ultrasound has a high sensitivity (>95%), but low specificity (<70%) in the diagnosis of urinary tract obstruction. Nevertheless, color Doppler is used through the evaluation of renal resistive indexes, ureteral jet and twinkling artifact.

Imaging in Chronic Kidney Disease.

Chronic kidney disease (CKD) diagnosis and staging are based on estimated or calculated glomerular filtration rate (GFR), urinalysis and kidney structure at renal imaging techniques. Ultrasound (US) has a key role in evaluating both morphological changes (by means of B-Mode) and patterns of vascularization (by means of color-Doppler and contrast-enhanced US), thus contributing to CKD diagnosis and to the follow-up of its progression. In CKD, conventional US allows measuring longitudinal diameter and cortical thickness and evaluating renal echogenicity and urinary tract status. Maximum renal length is usually considered a morphological marker of CKD, as it decreases contemporarily to GFR, and should be systematically recorded in US reports. More recently, it has been found to be a significant correlation of both renal longitudinal diameter and cortical thickness with renal function. Conventional US should be integrated by color Doppler, which shows parenchymal perfusion and patency of veins and arteries, and by spectral Doppler, which is crucial for the diagnosis of renal artery stenosis and provides important information about intrarenal microcirculation. Different values of renal resistive indexes (RIs) have been associated with different primary diseases, as they reflect vascular compliance. Since RIs significantly correlate with renal function, they have been proposed to be independent risk factors for CKD progression, besides proteinuria, low GFR and arterial hypertension. Despite several new applications, US and color Doppler contribute to a definite diagnosis in <50% of cases of CKD, because of the lack of specific US patterns, especially in cases of advanced CKD. However, US is useful to evaluate CKD progression and to screen patients at risk for CKD. The indications and the recommended frequency of color Doppler US could differ in each case and the follow-up should be tailored.

Clinical Scenarios in Chronic Kidney Disease: Vascular Chronic Diseases.

Vascular chronic diseases represent one of the leading causes of end-stage renal disease in incident dialysis patients. B-Mode ultrasound (US) and color Doppler (CD) have a high sensitivity and specificity in the diagnosis of vascular chronic diseases. US and CD should be used to identify subjects in the high risk population who are affected by main renal artery stenosis (RAS) and to identify and characterize patients without RAS who have chronic ischemic nephropathy caused by nephroangiosclerosis and/or atheroembolic disease. The most important CD parameters in the work-up of suspected RAS are increased peak systolic velocity and diastolic velocity, spectral broadening, high renal:aortic ratio and lateralization of renal resistive indexes (RIs). In the absence of direct or indirect signs of RAS, increases in intraparenchymal RIs, associated with systemic atherosclerotic disease, are indicative of microcirculation damage related to nephroangiosclerosis or atheroembolic disease.

Pathophysiology and Clinical Work-Up of Acute Kidney Injury.

Acute kidney injury (AKI), also known in the past as acute renal failure, is a syndrome characterized by the rapid loss of kidney excretory function. It is usually diagnosed by the accumulation of end products of nitrogen metabolism (urea and creatinine) or decreased urine output or both. AKI is the clinical consequence of several disorders that acutely affect the kidney, causing electrolytes and acid-base imbalance, hyperhydration and loss of depurative function. AKI is common in critical care patients in whom it is often secondary to extrarenal events. No specific therapies can attenuate AKI or accelerate renal function recovery; thus, the only treatment is supportive. New diagnostic techniques such as renal biomarkers might improve early diagnosis. Also ultrasonography helps nephrologists in AKI diagnosis, in order to describe and follow kidney alterations and find possible causes of AKI. Renal replacement therapy is a life-saving treatment if AKI is severe. If patients survive to AKI, and did not have previous chronic kidney disease (CKD), they typically recover to dialysis independence. However, evidence suggests that patients who have had AKI are at increased risk of subsequent CKD.

Clinical Scenarios in Chronic Kidney Disease: Parenchymal Chronic Renal Diseases - Part 2.

Secondary nephropathies can be associated with disreactive immunological disorders or with a non-inflammatory glomerular damage. In systemic lupus erythematosus (SLE), scleroderma and rheumatoid arthritis as in other connective tissue diseases, kidney volume and cortex echogenicity are the parameters that best correlate with clinical severity of the disease, even if the morphological aspect is generally non-specific. Doppler studies in SLE document the correlation between resistance indexes (RIs) values and renal function. Acquired immunodeficiency syndrome (HIV) causes different types of renal damage. At ultrasound (US), kidneys have almost a normal volume, while during superinfection they enlarge (coronal diameter >13 cm) and become globular, loosing their normal aspect. Cortex appears highly hyperechoic, uniform or patchy. Microcalcifications of renal cortex and medulla are a US sign that can suggest HIV. In amyloidosis, kidneys appear normal or increased in volume in the early stages of disease. Renal cortex is diffusely hyperechoic and pyramids can show normal size and morphology, but more often they appear poorly defined and hyperechoic. RIs are very high since the early stages of the disease. Nephromegaly with normal kidney shape is the first sign of lymphoma or multiple myeloma. In systemic vasculitis, renal cortex is diffusely hyperechoic, while pyramids appear hypoechoic and globular due to interstitial edema. When vasculitis determines advanced chronic kidney disease stages, kidneys show no specific signs. Microcirculation damage is highlighted by increased RIs values >0.70 in the chronic phase.