Reflux nephropathy

[Evidence-based medicine and vesicoureteral reflux]

Vesicoureteral reflux (VUR) remains one of the most controversial subjects in paediatric urology. Much literature has been published on VUR, making the understanding of this anomaly and its treatments quite opaque. Evidence-Based Medicine (EBM) should be helpful to clarify the various VUR approaches contained in the 6224 titles found on Medline using the keywords "vesicoureteral reflux" and "vesicoureteric reflux". These articles were critically reviewed and graded according to EBM scorings, with regard to their methodological designs. This review of VUR literature suggests that most of our knowledge is based on publications with a low level of evidence, and that EBM lacks arguments to support recommendations for VUR diagnostic and treatment. It appears yet that antenatal dilatation of the urinary tract and symptomatic urinary tract infections (UTI) justify VUR screening. Surgery should be discussed in recurrent UTIs or deterioration of renal function. There is no consensus in case of persistent asymptomatic VUR regarding indication and duration of antibio-prophylaxis, and selection of radical treatment.

Evaluation of acute pyelonephritis with DMSA scans in children presenting after the age of 5 years

It is generally believed that infants are more susceptible to development of renal scarring after pyelonephritis than children over 5 years old. This view has led to differences in investigations and treatment according to age. The aim of this prospective study was to assess the occurrence of renal parenchymal lesion in children over 5 years admitted with a first-time symptomatic urinary tract infection (UTI). Between October 2000 and April 2002, 52 children aged over 5 years who were admitted to our department with probable acute pyelonephritis (APN) and a positive urine culture were included in this study. All children received antibiotics for 14 days. During the acute phase of infection, scintigraphy with technetium-99m-labeled dimercaptosuccinic acid (DMSA) and ultrasonography (US) were done. Voiding cystourethrography (VCUG) was performed in all children early in the course of the illness, generally within 5-7 days of hospitalization. When scintigraphy showed renal parenchymal changes, repeat scintigraphy was done after at least 3 months to assess the progression of renal abnormalities. Of the 52 children with a first-time documented pyelonephritis, cortical scintigraphy showed renal lesion in 41 children (78.8%). US was normal in all children with normal renal scintigraphy, while it detected renal abnormalities in 16 of the 41 (39 %) with abnormal scintigraphy (p <0.0001). Topographic analysis of the 165 focal lesions showed that 42.4% were localized to the upper poles, 17.5% to the middle third, and 40% to the lower poles of the kidneys. Repeat scintigraphy showed persistent lesions corresponding to those on the initial scan in nine (28.2%) of the 32 children. Renal lesions had partly regressed in 23 (71.8%) of the patients who underwent repeat scintigraphy. Vesicoureteral reflux was observed in 13.4% of kidneys and renal parenchymal abnormalities were identified in 71.4% and 72.2% of renal units, respectively, with and without reflux ( p >0.05). In conclusion, our data did not confirm the conventional opinion that the risk of renal scarring after pyelonephritis is low in children over the age of 5 years. Our findings suggest that renal scintigraphy may be a more appropriate method of investigation than VCUG for evaluation of the children over 5 years with acute pyelonephritis. Additionally, the frequency of scintigraphic changes is high, and a strategy based exclusively on ultrasound findings would miss about 61% of the abnormal renal units. We recommend that all children, irrespective of age, will benefit from further investigations that might prevent or limit the development of scarring process and renal complications.

Sibling vesicoureteral reflux in multiple gestation births

BACKGROUND

Vesicoureteral reflux (VUR) is the most commonly inherited disease of the genitourinary tract. Although the majority of evidence supports a genetic cause, the tendency for this condition to spontaneously improve over time has made it difficult to determine the actual mode of transmission. We report the incidence of VUR in siblings of multiple gestation births and for the first time compare the relative incidence of reflux between identical and fraternal twins.

METHODS

A database consisting of all radionuclide cystograms and voiding cystourethrograms performed between the years 1986 and 1996 was searched for multiple gestation births. The medical records of each patient were evaluated for age at presentation, zygosity, reflux grade, and time to resolution. Children with secondary causes of VUR (eg, posterior urethral valves) were excluded. Triplets were treated as 2 pairs of twins for statistical analysis.

RESULTS

Forty-six pairs met the inclusion criteria (31 dizygotic and 15 monozygotic). Overall, 23 (50%) of 46 siblings of index cases had demonstrable VUR. Comparison of VUR prevalence between identical and nonidentical twins was revealing with 80% (12/15) of identical twins and 35% (11/31) of fraternal twins having VUR. When only the youngest individuals in each group were considered, 100% (7/7) of the monozygotics and 50% (5/10) of the dizygotics demonstrated this trait.

CONCLUSIONS

High concordance for VUR in identical twin siblings supports a genetic basis for the transmission of this disease. Results obtained from fraternal twin siblings provides convincing evidence that this trait is transmitted in an autosomal dominant fashion.

Demonstration of a "renogastric reflex" after rapid distension of renal pelvis and ureter in nonanesthetized patients

OBJECTIVES

Renal or ureteral diseases are often associated with nausea, vomiting, and abdominal pain. The aim of the current study was to investigate the cause of gastric manifestations that accompany renoureteral disorders.

METHODS

A 3F balloon-tipped catheter was introduced by means of a flexible cystoscope into the renal pelvis of 14 healthy volunteers (mean age 38.6 years; 10 men, 4 women), and the effect of rapid and slow renal pelvic and ureteral distension on the pyloric sphincter, gastric corpus, lower esophageal sphincter, and esophagus was recorded. The renal pelvis and ureter were then anesthetized and the tests repeated.

RESULTS

Rapid renal pelvic distension effected a significant rise in pressure in the renal pelvis at the 6-mL distension and above and in the pyloric sphincter at 10 and 1 2 mL. Loin and epigastric pain as well as nausea in all subjects and vomiting in 5 occurred at the 10 and 1 2-mL distensions. Slow renal pelvic distension caused a renal pelvic pressure rise at the 8-mL distension and above but no pressure changes in the pyloric sphincter or gastric corpus; loin pain, but not nausea or vomiting, occurred. Rapid ureteral distension at 1 mL was associated with loin and epigastric pain in all subjects and vomiting in 3. No epigastric pain, nausea, or vomiting occurred with slow ureteral distension. Renal pelvic or ureteral distension, slow or rapid, caused no pressure changes in the lower esophageal sphincter or esophagus. Distension of the anesthetized renal pelvis or ureter effected no gastric or esophageal pressure changes and no nausea or vomiting.

CONCLUSIONS

The study demonstrated the possible existence of a reflex relationship between the distension of the renal pelvis and ureter and the pressure of the pyloric sphincter. This reflex effect was reproducible and did not occur when the anesthetized renal pelvis or ureter was distended. We call this reflex relationship the "renogastric reflex" and suggest that it explains the cause of gastric manifestations that might occur with renoureteral disorders.

Ultrasonography of the ureters

It is difficult to visualize the normal canine or feline ureters ultrasonographically; however, diagnosis of various abnormalities associated with ureteral dilation is possible in many instances. Ultrasonography is a practical method for diagnosis of ectopic ureter, ureterocele, and certain causes of ureteral obstruction that compares favorably with contrast radiography because it is quicker, does not involve use of contrast media or ionizing radiation, and usually requires no sedation or anesthesia. Ultrasonography is a convenient method for examining adjacent organs, principally the kidneys and bladder, that may be affected in animals with ureteral abnormalities. Also, ultrasound guidance facilitates certain interventional diagnostic procedures for the ureters.

Pregnancy in women with reflux nephropathy

Reflux nephropathy is one of the most prevalent renal diseases and a leading cause of chronic renal failure in women-of childbearing age. To evaluate the issue and possible complications of pregnancy in women with reflux nephropathy, we retrospectively analyzed fetal and maternal outcome in 158 women who had 375 pregnancies between 1965 and 1994. The overall fetal death rate was 10.2% and tended to decrease in the 1985 to 1994 decade as compared to the preceding period (8.4% vs. 12.6%). The relative risk of fetal death was 4.8 times greater hypertension was present at conception than in normotensive patients. Fetal death rate was also higher in patients with impaired renal function that in those with serum creatinine < 0.11 mmol/liter at conception (36.7% vs. 7.7%, P < 0.0001). Urinary tract infection accounted for frequent morbidity but seldom resulted in fetal mortality. Maternal renal disease was unaffected by pregnancy, excepted for 4 of the 21 patients with pre-existing renal failure who exhibited an irreversibly accelerated course after pregnancy. We conclude that pregnancy is essentially successful and uneventful in patients diagnosed with reflux nephropathy who have normal blood pressure and preserved renal function, whereas the fetal prognosis is more compromised and there is a risk of accelerated progression of maternal renal disease when serum creatinine concentration is in excess of 0.22 mmol/ liter. This suggests that women with reflux nephropathy should preferably conceive before having reached that stage of renal failure.

Urinary tract infections. Old and new concepts

The recommendations for evaluation and management of pediatric patients with UTIs are summarized in Table 5. These recommendations were designed to minimize the risk of kidney damage in children with UTIs based on current perceptions of the pathogenesis of renal injury. The children at greatest risk for kidney damage are the infants and young children with febrile UTIs in whom effective treatment is delayed, those with gross VUR, and those with anatomic or neurogenic urinary tract obstruction. These recommendations likely will be modified as more is learned about the pathogenesis of renal injury associated with UTIs, as new therapeutic approaches are developed, and as imaging technology improves.

Reflux nephropathy and pregnancy

Reflux nephropathy is one of the renal diseases encountered most frequently in women of childbearing age. Patients with severe bilateral atrophy are the most likely to develop proteinuria, hypertension, focal glomerular sclerosis and progressive chronic renal failure, and those with persistent vesicoureteral reflux are the most likely to suffer recurrent pyelonephritic episodes. Often the disease is clinically latent and first manifests itself in pregnancy, mainly by urinary tract infection but also by proteinuria, hypertension, pre-eclampsia or renal failure. Pregnancy is most often successful and uneventful whenever renal function is normal or near normal and hypertension is absent at conception. Urinary tract infection accounts for frequent morbidity but rarely results in fetal mortality. By contrast, when renal function is significantly impaired, that is in patients whose plasma creatinine concentration is in excess of 0.20-0.22 mmol l-1 at conception, especially when hypertension is also present, there is clearly a high risk of fetal growth retardation or intrauterine death. Moreover, there is a striking risk of rapid worsening of renal function and hypertension, with accelerated progression towards end-stage renal failure. Thus, women with reflux nephropathy should attempt to conceive before the plasma creatinine concentration has reached 0.20 mmol l-1, and patients with values higher than these should be clearly advised of the high risk for both the pregnancy and the progression of the disease.

Congenital renal damage associated with primary vesicoureteral reflux detected prenatally in male infants

To assess the course of vesicoureteral reflux, we performed cystography, renal scintigraphy, and urography in all neonates with the prenatal diagnosis of renal pelvic dilation and revealed the presence of primary reflux (grades I to V) in 27 cases. Higher grades of reflux were associated with congenital renal damage, as shown by reduced tracer uptake during scintigraphy. Reflux was diagnosed more frequently in male infants (male/female ratio, 6:1), in many of whom bladder abnormalities were found by cystography. In another group of seven infants, in whom the reflux was associated with other urologic abnormalities, there was no sex prevalence. We conclude that severe primary reflux associated with hydronephrosis usually affects male infants and may be due to abnormal embryologic development of the male urethra, and that the kidney damage is primary and not the result of urinary tract infections. This pattern differs from that of vesicoureteric reflux diagnosed at an older age, which is observed most commonly in female patients.

Prevalence of hypertension in children with primary vesicoureteral reflux

This study was undertaken to determine the prevalence of hypertension in children with primary, uncomplicated vesicoureteral reflux (VUR) and to evaluate the relationship between blood pressure (BP), grade and duration of reflux, and renal scarring. Subjects were identified retrospectively during a 17-year period; of 146 subjects who agreed to participate, 129 (88.4%) were female. Mean age at diagnosis was 5.0 years (range, 1 month to 16 years), and at follow-up was 14.4 years (range, 5 months to 21 years). Mean duration of follow-up was 9.6 years. Renal scarring was detected in 34.3% of patients by intravenous pyelogram, ultrasonography, or both. The BP at diagnosis was linearly related to the grade of reflux, but values were not higher than expected norms for age. At follow-up, mean systolic and diastolic BP were at the 41.6 percentile and the 18.7 percentile, respectively. No patient's BP was above the 55th percentile. After a mean follow-up period of 10 years, we conclude that primary, uncomplicated VUR, regardless of the number of documented urinary tract infections, duration and severity of reflux, modality of therapy, presence of renal scarring, and duration of follow-up, is not associated with the development of hypertension. Hypertension does not appear to be a complication of VUR and urinary tract infection unless there is preexisting dysplasia.

Detection of Renal Injury in Patients with Vesicoureteral Reflux Using Dimercaptosuccinic-Acid (Dmsa) - Single Photon Emission Computed Tomography and Magnetic Resonance Imaging - Comparison with Dmsa-Planar Scintigraphy and Intravenous Pyelography

The value of “Technetium (Tc)-dimercaptosuccinic acid (DMSA) planar renal scintigraphy, DMSA single photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) for the assessment of renal injury related to vesico-ureterai reflux (VUR) were examined in 60 kidneys of 32 patients (28 bilateral, 4 unilateral) with primary VUR. The results were as follows: 1. Spatial resolution was best in MRI, then DMSA-planar and DMSA-SPECT; 2. For detecting renal injury, DMSA-SPECT (85%) and MRI (83.3%) were better than intravenous pyelography (55%) and DMSA-planar scintigraphy (65%). In conclusion, DMSA-SPECT or MRI should be performed in addition to DMSA-planar and IVP, to detect renal injury due to VUR.

Renal cortical scintigraphy in the diagnosis of acute pyelonephritis

Comparative clinical studies have shown renal cortical scintigraphy, using technetium-99m (99mTc)-labeled glucoheptonate or dimercaptosuccinic acid (DMSA), to be significantly more sensitive than either intravenous pyelography or renal sonography in the diagnosis of acute pyelonephritis. However, due to uncertainties about the diagnostic accuracy of the clinical and laboratory parameters used in these studies, true sensitivity of renal cortical scintigraphy was unknown. Therefore, we evaluated the accuracy of [99mTc]DMSA scintigraphy in the diagnosis of experimentally induced acute pyelonephritis in piglets using strict histopathologic criteria as the standard of reference. The sensitivity and specificity of the DMSA scan for the diagnosis of acute pyelonephritis were 91% and 99%, respectively, with an overall 97% agreement between the scintigraphic and histopathologic findings. Based on the results of this experimental study, we used the [99mTc]DMSA scan as the standard of reference for the diagnosis of acute pyelonephritis, and conducted a prospective clinical study of 94 children hospitalized with the diagnosis of acute febrile urinary tract infection (UTI). The aims of this study were (1) to determine the relationship among vesicoureteral reflux, P-fimbriated Escherichia coli, acute pyelonephritis, and renal scarring, and (2) to evaluate the diagnostic reliability of the clinical and laboratory parameters commonly used in the diagnosis of acute pyelonephritis. We documented acute pyelonephritis in 62 (66%) of 94 patients. Vesicoureteral reflux was demonstrated in 29 (31%) of the total group and in only 23 (37%) of 62 patients with acute pyelonephritis. The prevalence of P-fimbriae in the E coli isolates was 64% in the patients with acute pyelonephritis and 78% in those with a normal DMSA scan. Even in patients without reflux, P-fimbriae were found in 71% of isolates from the patients with acute pyelonephritis and in 75% of those with a normal renal scan. Follow-up DMSA scans were obtained in 33 patients with acute pyelonephritis in 38 kidneys. We found complete resolution of the acute inflammatory changes in 58% of the involved kidneys and renal scarring in the remaining 42%, including 40% of the kidneys associated with reflux and 43% of those without reflux.(ABSTRACT TRUNCATED AT 400 WORDS)

Results of surgical treatment of severe vesicoureteric reflux. Retrospective study of reflux grades 4 and 5

A series of 80 children underwent surgery in the Sophia Children's Hospital for gross reflux grades 4 and 5. In this retrospective study the success rate for ureteric reimplantation was 90%. Analysis of growth showed that after surgery the children tended to fall within the normal ranges for height and weight. Deterioration in renal function was progressive in 3 children. New renal scars developed in 13% of renal units. Initially non-refluxing kidneys showed no further deterioration. Moderate hypertension was found in only 4 patients.

Renal function after autotransplantation with direct pyelocystostomy. Long-term follow-up

The function of 20 human autologous kidney grafts was studied for 4 to 8 years (mean 5 1/2) after autotransplantation with a direct pyelocystostomy. The indications for the operation were low-grade, low-stage tumour of the renal pelvis and/or ureter, frequently recurrent renal stones and remaining outflow obstruction after pyeloplasty for hydronephrosis. The wide pyelocystostomy implies reflux of urine from the urinary bladder to the renal pelvis but no significant changes were found in glomerular or tubular function, studied with 51Cr-EDTA clearance, 131I-Hippuran renography, analysis of beta 2-microglobulin and total protein excretion in urine, and determination of concentration ability after administration of desmopressin. No increase in the severity or frequency of urinary tract infections was observed.

Glomerulosclerosis in obstructive uropathy

Obstructive uropathy is said to result in populations of remnant nephrons subject to hyperfiltration. We studied all obstructed renal tissue removed at our pediatric institution during a 10-year period for focal segmental glomerulosclerosis, which is the histological hallmark of hyperfiltration. Over-all, the histological specimens from 20 patients with ureteropelvic junction obstruction, 14 who underwent heminephrectomy for duplication anomalies and 5 with posterior urethral valves who underwent native nephrectomy were studied. Focal segmental glomerulosclerosis was one of the most common histological findings in these obstructed kidneys but it almost always was found in association with intense interstitial and periglomerular inflammation. We conclude that although focal segmental glomerulosclerosis is common in obstructive uropathological conditions it results from the inflammatory response within the renal parenchyma and not from the hyperfiltration of remnant nephron populations.

Reflux nephropathy and pregnancy

Reflux nephropathy is one of the most frequent renal diseases encountered in women of childbearing age. Patients with severe bilateral atrophy are the most likely to develop proteinuria, hypertension, focal glomerular sclerosis and progressive chronic renal failure, and those with persistent vesicoureteral reflux are the most likely to suffer recurrent pyelonephritic episodes. Often the disease is clinically latent and first manifests itself in pregnancy, mainly by urinary tract infection but also by proteinuria, hypertension, pre-eclampsia or renal failure. Pregnancy is most often successful and uneventful whenever renal function is normal or near normal and hypertension is absent at conception. Urinary tract infection accounts for frequent morbidity but rarely results in fetal mortality. By contrast, when renal function is significantly impaired, that is in patients whose plasma creatinine concentration is in excess of 0.18-0.20 mmol/l at conception, especially when hypertension is also present, there is clearly a high risk of severe fetal growth retardation or intrauterine death. Moreover, there is a striking risk of rapid worsening of renal function and hypertension, with accelerated progression towards end-stage renal failure. Thus, women with reflux nephropathy should attempt to conceive before the plasma creatinine concentration has reached 0.18 mmol/l, and patients with values higher than these should be clearly advised of the high risk for both the pregnancy and the progression of the disease.

Renal dysgenesis and cystic disease of the kidney: a report of the Committee on Terminology, Nomenclature and Classification, Section on Urology, American Academy of Pediatrics

We believe that the confusion regarding abnormal renal development could be reduced by more precise terminology. Therefore, we suggest precise definitions for dysgenesis, hypoplasia, dysplasia, hypodysplasia, aplasia and agenesis of the kidney. We suggest the term reflux nephropathy be a generic label for any instance of abnormal renal morphology (gross or microscopic) associated with vesicoureteral reflux. Hypoplasia and hypodysplasia can be subclassified on the basis of associated urological criteria. There have been many previous attempts to classify cystic disease of the kidney but none has been accepted collectively by pathologists, urologists, nephrologists and radiologists. On the basis of known patterns of inheritance, a classification is outlined in which renal cystic disease is divided into 2 major groups: genetic and nongenetic. Each entity is discussed.

Vesicoureteral reflux and lower urinary tract dysfunction: evidence for 2 different reflux/dysfunction complexes

We examined retrospectively 458 children 2 to 15 years old without neuropathic conditions or a gross anatomical abnormality to determine whether there was an association between lower urinary tract dysfunction and vesicoureteral reflux. We identified 2 different types of reflux/dysfunction complexes with contrasting urodynamic characteristics. One type included bladder instability with powerful voiding contractions of the bladder and reflux that frequently occurred on 1 side only. Reflux nephropathy or the presence of an upper urinary tract abnormality is rare. In the other type the bladder contracted poorly during voiding and overactivity of the urethral closure mechanism often was observed. The bladder usually was stable and the reflux occurred frequently on both sides. Reflux nephropathy or the presence of an upper urinary tract abnormality is relatively common. Direct videourodynamic observations of reflux in a second group of children confirmed the existence of these 2 types of reflux/dysfunction complexes.

Urinary tract infections in infants and children. Guidelines for averting permanent damage

Urinary tract infection (UTI) is common in childhood and, early in life, is often associated with vesicoureteral reflux or other urinary tract anomalies. Since the combination of reflux and infection can cause renal scarring and impaired renal function, identification of children at risk and provision of close follow-up are important. Diagnosis in the first year of life relies on a high index of suspicion on the part of the clinician, as signs and symptoms are nonspecific. Reliable cultures are the cornerstone of accurate diagnosis and will be the basis for selection of acute and long-term management. Vigilant follow-up of all children with UTI can prevent ultimate morbidity.