Renal Relevant Radiology: Use of Ultrasound in Kidney Disease and Nephrology Procedures

Ultrasound is commonly used in nephrology for diagnostic studies of the kidneys and lower urinary tract and to guide percutaneous procedures, such as insertion of hemodialysis catheters and kidney biopsy. Nephrologists must, therefore, have a thorough understanding of renal anatomy and the sonographic appearance of normal kidneys and lower urinary tract, and they must be able to recognize common abnormalities. Proper interpretation requires correlation with the clinical scenario. With the advent of affordable, portable scanners, sonography has become a procedure that can be performed by nephrologists, and both training and certification in renal ultrasonography are available.     

Possibilités et limites de l'échotomographie d'urgence dans l'insuffisance rénale majeure

One hundred patients with renal failure and hospitalized in emergency underwent renal, abdominal and or cardiac ultrasonics canning within the first 48 hours following their admission. In 58 patients with acute renal failure (ARF), renal sonography diagnosed urinary tract obstruction in 15/16 patients, ARF without obstruction in 39/40 patients, and renal vein and/or venal caval thrombosis in 2 patients. Abdominal and cardiac sonography were often useful for diagnosing the cause of associated sepsis: intra-abdominal abscess (4 cases), bacterial endocarditis (3 cases) and septic pericarditis (1 case). In 42 patients with chronic renal failure, sonography identified small kidneys in 31 patients, normal kidneys in 7 patients, and enlarged kidneys in 4 patients, including 3 with polycystic disease.Sonography seems in patients with renal failure a reliable method for diagnosing urinary tract obstruction and polycystic disease, giving the kidney size, identifying and extrarenal collection in case of an associated sepsis, and localizing the kidney for percutaneous biopsy. Sonography may occasionally give some information on the nature and the site of obstruction, or on the renal vessels, but is until now of little help in recognizing a urinary calculus or the nature of a renal parenchymal disease in adults.     

Nonutility of cineurograms in children with congenital heart disease

Cineurography is often performed after cineangiocardiography to look for occult congenital urinary tract disease. The accuracy of cineurography was investigated in 171 patients by comparing cineurograms with renal sonograms. One hundred fifteen cineurograms (67%) showed both kidneys well enough to allow assessment of renal structure and function and the results were confirmed in 112 by ultrasonography; 3 cineurograms yielded false-positive results. Limited or no information was obtained from cineurograms of 56 patients (33%) because of nonvisualization or poor visualization of 1 or both kidneys. Of the 11 patients (6%) with urinary tract disease, only 3 were correctly assessed by cineurography. Ultrasonography discovered all 11 renal abnormalities and produced only 1 false-positive result. These data indicate that cineurography is a poor screening test and should be abandoned. When uroradiologic screening is necessary for high-risk patients, sonography is recommended.     

Clinical Implications of the Solitary Functioning Kidney

Congenital anomalies of the kidney and urinary tract are the major cause of ESRD in childhood. Children with a solitary functioning kidney form an important subgroup of congenital anomalies of the kidney and urinary tract patients, and a significant fraction of these children is at risk for progression to CKD. However, challenges remain in distinguishing patients with a high risk for disease progression from those patients without a high risk of disease progression. Although it is hypothesized that glomerular hyperfiltration in the lowered number of nephrons underlies the impaired renal prognosis in the solitary functioning kidney, the high proportion of ipsilateral congenital anomalies of the kidney and urinary tract in these patients may further influence clinical outcome. Pathogenic genetic and environmental factors in renal development have increasingly been identified and may play a crucial role in establishing a correct diagnosis and prognosis for these patients. With fetal ultrasound now enabling prenatal identification of individuals with a solitary functioning kidney, an early evaluation of risk factors for renal injury would allow for differentiation between patients with and without an increased risk for CKD. This review describes the underlying causes and consequences of the solitary functioning kidney from childhood together with its clinical implications. Finally, guidelines for follow-up of solitary functioning kidney patients are recommended.     

Vesicoureteral reflux in children

Vesicoureteral reflux is a common disease in children and is usually associated with urinary tract infections and renal scars. Renal damage associated with vesicoureteral reflux occurs secondary to renal maldevelopment during fetal life or renal infections in children and may produce hypertension, diseases in pregnancy and chronic renal failure. Bladder dysfunction may be responsible for persistent reflux and renal scars. In order to prevent renal damage, early diagnosis and prompt medical treatment or surgical correction are advised in a selected group of children. In the past all children with urinary tract infections were investigated with voiding uretrocystogram and received long-term antibiotic prophylaxis or surgery. In recent years several trials have provided information that suggest it is better to reduce the number of diagnostic and surgical procedures in children affected by vesicoureteral reflux.     

In utero intervention for urologic diseases

The burgeoning use of prenatal ultrasonography has prompted discussion of the feasibility and capabilities of fetal intervention for urologic disorders. On the basis of the capabilities of fetal intervention, three prenatally diagnosed anomalies are of primary interest to urologists: congenital adrenal hyperplasia (CAH), lower urinary tract obstruction (LUTO) and myelomeningocele. Various interventions (surgical or pharmacological) are being developed for fetuses with these diagnoses. For fetuses with CAH or LUTO, successful outcomes have certainly been demonstrated, although no results from prospective randomized trials have been published. In utero treatment of CAH is accomplished through oral administration of glucocorticoids to the expectant mother. However, the long-term effects of this strategy have been insufficiently studied and remain undetermined. In the fetus with a LUTO, prenatal intervention has primarily been accomplished by placement of a vesicoamniotic shunt. Although this technique results in improved perinatal survival according to several systematic reviews of the literature, the data originate from small, heterogeneous populations of patients. By contrast, a randomized controlled trial of fetal myelomeningocele closure resulted in greatly reduced rates of both ventriculoperitoneal shunt placement and hydrocephalus. The future of fetal intervention in urology is contingent upon improved methods of studying the clinical outcomes of such treatments.     

Treatment of acute obstructive renal failure with high-dose methylprednisolone

High-dose methylprednisolone sodium succinate (Solu-Medrol) therapy was administered to two patients with acute renal failure and anuria secondary to cancer-related urinary tract obstruction. Following the administration of intravenous methylprednisolone, obstruction was relieved, as evidenced by increased urinary flow and improvement of renal function. The salutary effect of methylprednisolone is probably related to the relief of obstruction secondary to a decrease in tumor-associated edema similar to the effect obtained in patients with brain tumors and spinal cord compression by epidural metastases. The temporary improvement in renal function allowed time for more definitive therapy to be instituted under more favorable clinical conditions.     

Bacteriuria in pregnancy

The urinary tract undergoes profound physiologic and anatomic changes during pregnancy that facilitate the development of symptomatic urinary tract infections in women with bacteriuria. While the adverse effects of asymptomatic bacteriuria on maternal and fetal health continue to be debated, it is clear that asymptomatic bacteriuria is the major risk factor for developing symptomatic urinary tract infection and that symptomatic infections are associated with significant maternal and fetal risks. Because the majority of symptomatic urinary tract infections develop in women with bacteriuria earlier in pregnancy, treatment of bacteriuria is undertaken to prevent symptomatic infections. All women should be screened at the first antenatal visit, which is reliably and inexpensively done with a dipstick culture. Short-course therapy is as effective as prolonged therapy and should be followed with a repeat culture to document clearing of the bacteriuria. Failure to eliminate bacteriuria with repeated therapy or recurrence with the same organism is indicative of renal parenchymal infection or a structural abnormality. All women with persistent bacteriuria or recurrent infection should have follow-up cultures and a complete urologic evaluation after delivery.     

Prenatal diagnosis of fetal congenital mesoblastic nephroma by ultrasonography combined with MR imaging: A case report and literature review

Rationale:Fetal congenital mesoblastic nephroma (CMN) is a rare renal tumor, characterized by polyhydramnios, premature birth, and neonatal hypertension. In the prenatal stage, it is particularly difficult to diagnose CMN either by ultrasonography or magnetic resonance imaging (MRI). Thus, CMN is frequently detected in the third trimester in the clinical scenario.Patient concerns:A 29-year-old G2P0 pregnant woman took routine prenatal examinations in our hospital. The fetal right kidney abnormality was not observed after 2 systematical ultrasonic examinations (at 24 and 31 weeks of gestation respectively), and only an increase was noticed in the amniotic fluid index (from 19.3 to 20.8 cm).Diagnosis:CMN was detected by antenatal ultrasonography and MRI as a fetal right renal mass at 35 weeks of gestation in our hospital.Interventions:The pregnant woman was admitted at a gestational age of 38 weeks and 5 days due to alterations in renal function. Further, the pregnant woman was administered with “oxytocin” to promote delivery, and the neonate underwent a right nephrectomy on the 9th day after birth.Outcomes:The pathological examination confirmed a cellular type of right CMN. The neonate recovered well after operation without adjuvant treatment. During 6 months of follow-up, the neonate grew well and showed no signs of recurrence or metastasis.Conclusion:Polyhydramnios detected during prenatal examination required attention due to the risk of malformation of fetal urinary system. Prenatal ultrasonography combined with MRI could not only clearly identify the origin of the tumor, but also distinguish the correlation between the tumor and adjacent structures, thereby leading to early diagnosis and favorable prognosis.     

Iatrogenic emphysematous pyelonephritis in a renal transplant patient

Abstract: Emphysematous pyelonephritis (EPN) is a rare condition that typically occurs in patients with diabetes mellitus, urinary tract obstruction, or immunosuppression such as solid organ transplant recipients. It has high mortality and frequently requires nephrectomy to achieve cure, although percutaneous drainage has been reported to be successful in some patients. We report a renal transplant recipient with underlying diabetes mellitus who developed iatrogenic EPN. The patient initially presented with dyspnea and was admitted for cardiac evaluation. There was no evidence of urinary tract infection at the time of admission. The patient developed high‐grade fever 3 days after admission. Despite intravenous (IV) antibiotic therapy, the patient developed acute renal failure requiring hemodialysis. Studies revealed Klebsiella bacteremia and EPN. We believe that urinary tract infection was precipitated by urinary bladder catheterization performed on the day of admission. Despite 2 weeks of IV antibiotic therapy, infection persisted with progressive extension of gas into the perinephric space on repeat imaging. The patient underwent a transplant nephrectomy with subsequent clinical recovery. This case illustrates that antibiotics alone are often inadequate to cure and preserve renal function in EPN despite immediate therapy. Furthermore, this patient underscores the risk of serious infection precipitated by urinary bladder catheterization in immunocompromised patients.     

Urological Aspects of Management

Renal colic describes the acute, severe, and paroxysmal pain caused by the obstruction, distension, and resultant increase in intraluminal pressure of the urinary tract. The treatment of renal colic is aimed at relief of symptoms, facilitating urinary drainage to preserve renal function and treat infection and ultimately removal or passage of the obstructing stone. The medical management of renal colic is directed at mitigating, through pharmacologic intervention, one or more of the complex processes contributing to the clinical sequelae of obstruction including pain, nausea, vomiting, and irritative voiding symptoms. Numerous medications and combinations of medications have been employed with varying degrees of clinical success. Urgent interventions are typically directed at bypassing ureteral obstruction in order to palliate the patient until such time as definitive treatment may be accomplished or facilitate drainage to further the treatment of urinary tract infection. Timing and mode of urgent intervention are dependent on clinical factors, clinician expertise, and preference and the availability of specialized equipment. Definitive management of ureteral stones is typically performed in an elective fashion and seeks to balance the risks of intervention with the clinical benefits of the various treatment modalities. Treatment approaches vary according to clinical indications, patient preference, clinician expertise, and the availability of facilities and equipment. This section covers current supporting evidence and rationale, indications and techniques for the medical management, urgent intervention, and definitive management of acute renal colic caused by ureteral stones.     

Ultrasound and color Doppler applications in nephrology. The normal kidney: anatomy, vessels and congenital anomalies

Gray-scale ultrasound is the diagnostic technique of choice in patients with suspected or known renal disease. Knowledge of the normal and abnormal sonographic morphology of the kidney and urinary tract is essential for a successful diagnosis. Conventional sonography must always be complemented by Doppler sampling of the principal arterial and venous vessels. B-mode scanning is performed with the patient in supine, prone or side position. The kidney can be imaged by the anterior, lateral or posterior approach using coronal, transverse and oblique scanning planes. Morphological parameters that must be evaluated are the coronal diameter, the parenchymal thickness and echogenicity, the structure and state of the urinary tract, and the presence of congenital anomalies that may mimic a pseudomass. The main renal artery and the hilar-intraparenchymal branches of the arterial and venous vessels should be accurately evaluated using color Doppler. Measurement of intraparenchymal resistance indices (IP, IR) provides an indirect and quantitative parameter of the stiffness and eutrophic or dystrophic remodeling of the intrarenal microvasculature. These parameters differ depending on age, diabetic and hypertensive disease, chronic renal glomerular disease, and interstitial, vascular and obstructive nephropathy.     

Fractional excretion of sodium. Exceptions to its diagnostic value

Determining the cause of acutely deteriorating renal function is a common problem in clinical nephrology. The fractional excretion of filtered sodium (FENa) has been demonstrated to be a reliably discriminating test between prerenal azotemia and acute tubular necrosis. However, with increasing clinical use of the FENa, numerous reports of low FENa (less than 1%) have appeared. The clinical settings of these reports include oliguric and nonoliguric acute tubular necrosis, urinary tract obstruction, acute glomerulonephritis, hepatorenal syndrome, renal allograft rejection, sepsis, and drug-related alterations in renal hemodynamics. One particular urinary index cannot be expected to reliably discriminate between prerenal azotemia and acute renal failure in all cases. The utility of the FENa test in the differential diagnosis of acute renal failure must be interpreted in conjunction with the patient's clinical course and the use of additional urinary and serum tests.     

Urinary tract infection in patients with diabetes mellitus

Urinary tract infection is an important infection in patients with diabetes mellitus. Asymptomatic and symptomatic infections of urinary tract, and also some rarer serious complications of urinary tract infections (papillary necrosis, renal and perirenal abscess, emphysematous and xantogranulomatous pyelonephritis and s.o.). Incidence, outcome and treatment in patients with diabetes, which deserve special clinical attention, are commonly viewed by prism of personal opinion, and should be based on clinical studies, focused on this topic.     

Treatment with a single daily dose of gentamicin in urinary tract infection in relation to the site of infection

Twenty-three patients with various types of recurrent urinary tract infection were treated with a single daily dose of 160 mg gentamicin for eight to nine days. The treatment eliminated bacteriuria in 19 patients. Evaluation of the therapeutical results according to the site of infection showed elimination of bacteriuria in all patients with lower urinary tract infection. Thus a single daily dose of gentamicin can be recommended in recurrent lower urinary tract infection, and also in upper urinary tract infection not associated with a major impairment of renal function.     

Antibody-coated bacteria as an indicator of the site of urinary tract infection in renal transplant recipients receiving immunosuppressive agents.

Distinguishing an infection in the upper urinary tract from one in the lower urinary tract is especially important in renal transplant patients. Although the presence of antibody-coated bacteria in the urine has been shown by others to be a reliable indication of an infection in the upper urinary tract, it was not known whether sufficient antibody to coat the bacteria would be produced in a renal transplant recipient undergoing immunosuppression. We used a fluorescent test for detecting antibody-coated bacteria in the urine to follow 80 renal transplant patients prospectively for six months. Antibody-coated bacteria were detected in specimens from four patients with a clinical picture compatible with, or histopathologic evidence of, pyelonephritis. The origin of bacteriuria in a fifth patient was indeterminate both clinically and by the fluorescent antibody test. Twenty-three other patients with bacteriuria without clinical or histopathologic evidence of pyelonephritis had negative tests for antibody-coated bacteria. One patient with pyelonephritis in her own end-stage kidney had persistent bacteriuria with a negative fluorescent antibody test. Her transplanted kidney, however, was not infected.     

Malakoplakia after kidney transplantation: Case report and literature review

Malakoplakia is a granulomatous disease associated with an infectious etiology, usually involving the urinary tract. It reveals itself as a recurrent urinary tract infection (r‐UTI), and in some cases, it is associated with impairment of renal function. Immunosuppression is one of its main associated factors, and it has been increasingly described in patients with solid organ transplantation (SOT), mainly kidney transplantation. Macroscopically, it can form masses and sometimes it may be confused with neoplasia, which is why histological findings are fundamental for the diagnosis. Here, we present a case of bladder malakoplakia, manifested by r‐UTI from Escherichia coli in a patient with renal transplantation, refractory to long‐term antibiotic treatment and reduction in immunosuppression, which resolved after surgical management. We also summarize the clinical characteristics of malakoplakia and compare them with previous reports in the literature on SOT.     

Intravenous pyelography: the case against its routine use

PURPOSE: To critically appraise four common uses of intravenous pyelography in adults. DATA IDENTIFICATION: We reviewed the literature on the use of intravenous pyelography for four clinical indications. STUDY SELECTION: We analyzed the literature to determine the proportion of intravenous pyelograms producing clinically useful information (yield) in four clinical situations. The best estimate of its accuracy (sensitivity and specificity) for associated pathologic findings was determined. The implications of using the test on the outcomes of patients and costs were evaluated. RESULTS OF DATA SYNTHESIS: The yield of significant abnormalities in patients having prostatectomy is small; intravenous pyelography does not specifically indicate ureteral obstruction, and is not sensitive or specific enough for screening for urinary tract malignancies. Many false-positive results, little benefit, and significant costs can be expected. When used before hysterectomy, intravenous pyelography does not reduce injury to the ureters, and the yield of unexpected abnormalities is small. The use of the test to screen for unexpected anatomic abnormalities in adult women after urinary tract infections has not led to improved outcomes or prevention of impaired renal function. Acquired causes of obstruction will be suggested by the history or physical examination. In hypertensive adults, intravenous pyelography is not accurate enough in detecting renal artery stenosis or in predicting favorable outcomes of renal artery surgery. Also, large costs are generated by high false-positive rates, and candidates for successful surgery are not reliably identified. CONCLUSIONS: Selective use of intravenous pyelography is recommended for patients before prostatectomy or hysterectomy, in women after urinary tract infections, and in adults whose hypertension may have a renovascular cause. Use should be reserved for patients whose history and physical examination raise specific questions for which this test could provide an answer that would affect treatment.     

妊娠期尿石症诊疗体会

目的 探讨妊娠期尿石症的诊断和治疗方法.方法 对28例妊娠期尿石症的临床资料及诊治过程进行回顾性分析,结合文献讨论其临床特点和诊疗方法.结果 25例B超检查发现有结石;全部患者均先行保守治疗,但有反复尿路感染并不完全梗阻,肾绞痛反复发作者行膀胱镜逆行置入双J管;输尿管结石合并肾积水患者行经皮肾造瘘;全部患者均足月分娩.结论 妊娠期尿石症的诊断首选B超检查,治疗上以保守治疗为主,不提倡创伤较大的治疗方法,以避免出现流产或早产;出现肾功能损害、尿路感染或保守治疗无效时,应及时进行外科治疗,主要是经膀胱镜逆行置入双J管、经皮肾造瘘和输尿管镜碎石.     

Obstructive uropathy in childhood

"Obstructive uropathy" is a generic term which combines different diseases in infants and childhood. Both the upper and lower urinary tract may be affected. Diseases of the urinary tract can cause an intrinsic obstruction. Sometimes tumours may cause a compression and as secondary effect an obstruction (extrinsic). Ultrasound is the key diagnostic tool and shows dilatation of the obstructed urinary tract. But for the functional exploration of babies and toddlers, renal scanning and X-ray examinations are necessary. These examinations lead to an exposure to radiation which necessitates careful indication. Some of the congenital diseases (for example ureteropelvic junction obstruction, megaureter) show a maturation without any intervention. So one has to decide whether to wait and see or to operate. A percutaneous nephrostomy or a DJ-catheter is not often used in the treatment of obstruction in general. These forms of drainage are more often used in the treatment of stones or of extrinsic obstruction. A pyelocutaneostomy or ureterocutaneostomy is a special surgical procedure in pediatric urology for transient drainage of the upper urinary tract (megaureter). The operation of a seriously ill new-born should be done in a centre for pediatric urology and pediatric nephrology. When the upper urinary tract is dilated, patients may need an antibiotic prophylaxis, because the dilatation of the upper urinary tract increases the risk of urinary tract infections (UTI). The indication for antibiotic prophylaxis should by guided by the criteria of the APN-Consensus Paper. Long-term follow-up is necessary and should comprise ultrasound, physical examination, controlling the blood pressure, urine analysis and blood tests. The aims of diagnostics, treatment and long-term follow-up are the preservation of renal function and to protect the children from UTI. This goal must be reached under conditions that are appropriate for children and their parents.