The interrelationship between vesico-ureteric reflux, trigonal abnormalities and a bifid pelvicalyceal collecting system: a family study

Duplex kidney: not just a drooping lily

INTRODUCTION

Duplex kidneys are common, mostly asymptomatic and of no clinical significance. However, they can be associated with significant pathology, often with long-term morbidity. There is minimal literature on the review of the duplex kidney, its associated anomalies and complications. The purpose of this paper is to review our experience of imaging the spectrum of abnormalities associated with duplex kidneys in the paediatric population and correlate this with contemporary literature.

METHOD

A retrospective review of the radiology database in a tertiary paediatric centre was performed. A word search of the Radiology Information System for 'duplex' of patients under the age of 16 was undertaken and limited to studies performed between 2006 and 2013.

RESULTS

Two hundred seventy-four patients were identified (age range 0-16, median 3 years, gender 59.9% female) who had 836 studies: ultrasound 598/836 (71.6%), nuclear medicine 180/836 (21.5%), micturating cystourethrogram 52/836 (6.2%), MRI 5/836 (<1%) and CT scan 1/836 (<1%). Patients were categorised as duplex and no complication (151/274 = 55.1%), upper moiety obstruction, lower moiety reflux/scarring, multicystic dysplastic kidney, abnormal ureteric insertion and other pathology.

CONCLUSION

Duplex kidneys are common and often not clinically significant. However, this study demonstrates almost 50% of paediatric patients investigated for duplex kidneys had complications requiring treatment. The most common complications were upper moiety obstruction associated with a ureterocele and lower moiety vesicoureteric reflux. Ultrasound was the most common modality for early detection of these complications.

Polydimethylsiloxane (macroplastique®) injection for vesicoureteral reflux in duplex ureters: a comparison with single renal systems

OBJECTIVE

VUR in patients with a duplex system (DS) is often treated by open surgery. The aim of this study was to evaluate the efficacy of subureteric polydimethylsiloxane (Macroplastique(®)) injection (SMING) in the management of VUR in duplex and single (SS) renal systems.

PATIENTS AND METHODS

Fifteen children (24 refluxing renal units) with VUR in DS underwent SMING. VUR was more frequent in the lower moiety. VUR was graded moderate/severe in 88% of renal units. There was a history of urinary tract infections in 40% of cases. The outcome for DS patients was compared with 44 children (60 refluxing renal units) with moderate/severe VUR in SS.

RESULTS

The VUR resolution/improvement rate was 88% in DS and 95% in SS patients. Ureteric reimplantation was required because of recurrent VUR in 13% and 7% of DS and SS groups, respectively. Transient ureteral obstruction was observed in 1/15 and 5/44 patients. Two required double-J ureteric stenting for 3 months.

CONCLUSION

SMING seems an effective treatment for VUR in both DS and SS patients, even in severe cases. The complication rate does not significantly differ between the two groups.

Primary, nonsyndromic vesicoureteric reflux and nephropathy in sibling pairs: a United Kingdom cohort for a DNA bank

BACKGROUND AND OBJECTIVES

Primary vesicoureteric reflux (VUR) can coexist with reflux nephropathy (RN) and impaired renal function. VUR appears to be an inherited condition and is reported in approximately one third of siblings of index cases. The objective was to establish a DNA collection and clinical database from U.K. families containing affected sibling pairs for future VUR genetics studies. The cohort's clinical characteristics have been described.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Most patients were identified from tertiary pediatric nephrology centers; each family had an index case with cystography-proven primary, nonsyndromic VUR. Affected siblings had radiologically proven VUR and/or radiographically proven RN.

RESULTS

One hundred eighty-nine index cases identified families with an additional 218 affected siblings. More than 90% were <20 years at the study's end. Blood was collected and leukocyte DNA extracted from all 407 patients and from 189 mothers and 183 fathers. Clinical presentation was established in 122; 92 had urinary tract infections and 16 had abnormal antenatal renal scans. RN was radiologically proven in 223 patients. Four patients had been transplanted; none were on dialysis. In 174 others aged >1 year, estimated GFR (eGFR) was calculated. Five had eGFR 15 to 59 and 48 had eGFR 60 to 89 ml/min per 1.73 m(2). Values were lower in bilateral RN patients than in those with either unilateral or absent RN.

CONCLUSIONS

The large DNA collection from families with VUR and associated RN constitutes a resource for researchers exploring the most likely complex, genetic components predisposing to VUR and RN.

Duplex systems

Duplex kidneys occur in 0.8% of the general population, many of whom are asymptomatic. Children with duplex kidneys may be prone to urinary tract infections because of vesico-ureteric reflux or obstruction. Surgical management is usually required once symptoms occur. Increasing numbers of duplex kidneys are now prenatally diagnosed by ultrasound, resulting in the development of early postnatal strategies to try and reduce morbidity.

Absence of PAX2 gene mutations in patients with primary familial vesicoureteric reflux

Vesicoureteric reflux (VUR) is a common childhood condition characterised by regurgitation of urine from the bladder to the kidney. It is the commonest cause of end stage renal failure in children and an important cause in adults. Primary VUR is often familial, suggesting that genetic factors play an important role in its aetiology. Recently, VUR was observed as part of a syndrome, involving optic nerve colobomas and renal anomalies, caused by mutations of the PAX2 gene. PAX2 is a member of the paired box family of genes and is expressed in the ureteric bud and differentiating nephrogenic mesenchyme of the developing kidney. PAX2 has been shown to play a critical role in the development of both the kidney and the ureter. The occurrence of VUR in one family with the PAX2 mutation, and the expression pattern of PAX2 in developing ureteric bud, strongly suggested that PAX2 could be the cause of primary familial VUR. Single strand conformational polymorphism (SSCP) analysis of 23 affected subjects in eight families with primary familial VUR showed no alterations in exons 2-5 of the PAX2 gene. In addition, a polymorphic dinucleotide repeat marker located within the PAX2 gene segregated independently of the disease trait in one large family who primarily had VUR or reflux nephropathy. These results suggest that PAX2 is not a major cause of primary familial reflux.

Unravelling the genetics of vesicoureteric reflux: a common familial disorder

Primary vesicoureteric reflux (VUR) is one of the more common genetic disorders. Little is yet known about the genetics of this potentially manageable childhood condition, which is characterised by regurgitation of urine from the bladder to the kidney. The VUR phenotype is associated with shortness of the submucosal segment of the ureter due to congenital lateral ectopia of the ureteric orifice. VUR is found in 30-50% of infants and young children with a urinary tract infection. A serious concern in families with an affected patient is that approximately one half of siblings or offspring will be affected, but up to a half of these affected siblings and offspring may be asymptomatic in childhood. If left untreated, these patients may present later in life with proteinuria, hypertension or renal failure. VUR is the commonest cause of end-stage renal failure in children, and an important cause in adults. As the kidney damage resulting from severe VUR is preventable, early detection is desirable. The techniques for clinical diagnosis are invasive and costly, reinforcing the importance of identification of a gene for VUR to facilitate genetic screening. Although family studies suggest a major dominant gene, the inheritance pattern is still a matter of debate. In rare instances, VUR occurs in association with other diseases, such as the coloboma-ureteric-renal syndrome, which is caused by a PAX2 gene mutation. In this review, we present evidence that this common disorder may be caused by mutations in the developmental pathway of which the PAX2 gene forms a part.

Urinary tract infection: a comparison of four methods of investigation

The optimal regimen for investigating children with urinary tract infection (UTI) remains uncertain. Ultrasonography, contrast micturating cystourethrography (MCU), intravenous urography (IVU), and technetium-99m dimercaptosuccinic acid (DMSA) studies were performed in 58 children with UTI under 14 years of age attending two teaching hospitals and the results compared. All four investigations were normal in 12 children. In 36 with vesicoureteric reflux (VUR) on MCU, dilatation was reported on ultrasonography in eight children. Radiological renal scarring was seen in 20 children; it was suspected on ultrasonography in nine, with dilatation alone in four, and a normal report in seven. Duplex kidneys identified on IVU were unrecognised on ultrasonography or DMSA studies; ultrasonography showed no change corresponding to presumed acute defects on DMSA studies that later resolved. Disparities were observed at all ages. This study suggests that ultrasonography is unreliable in detecting VUR, renal scarring, or inflammatory change and, alone, is inadequate for investigating UTI in children.

The transmission of vesicoureteral reflux from parent to child

Vesicoureteral reflux is now recognized to be hereditary and familial. The incidence of reflux in siblings has proved to be significant but less is known about the incidence of reflux in the offspring of known reflux patients. In an ongoing prospective series of reflux screening we identified 23 patients of childbearing age with a known history of reflux and screened their 36 offspring with an awake voiding cystourethrogram. Of these 36 offspring 24 (66%) exhibited vesicoureteral reflux. The literature was also reviewed to determine the incidence of parent/child reflux from reported cases. This review revealed a 65% rate of reflux in the offspring of known patients. Our preliminary results coupled with those in the literature signify a need to screen the offspring of known reflux patients and suggest a rethinking of the genetic transmission for this trait. While vesicoureteral reflux could still be a multifactorial genetic trait with a major gene, consideration must also be given to an autosomal dominant inheritance pattern.

Family screening for duplex kidneys

Family screening was offered to the relatives of 57 patients with duplex renal systems and this resulted in the detection of another 37 cases. A further 5 first degree relatives had abnormal intravenous urography, so that 25% of the screened relatives had significant renal abnormalities. It is suggested that there may be a place for screening the whole family if renal tract duplex is detected.

Electron microscopic study of pyelointerstitial reflux scars

In addition to confirming the established light microscopic findings, electron microscopic assessment of renal tissue with pyelointerstitial reflux damage also provides other important information. Isolated tubular epithelial cells and small tubular epithelial cell complexes, the earliest formative phase of thyroid-like lesions, were observed after subtotal tubular destruction. Moreover, secretory granule-like structures, identified by immunohistologic methods as renin granules, were found in tubular epithelium, apparently atrophic and cell-rich glomeruli, and walls of tortuous arterioles. Various stages of glomerular scarring were documented in the early phase of glomerular destruction and electron-dense material (IgM) was identified. Electron microscopy plays an important role in differentiating thin-walled vessels (lymphatic vessels, capillaries, venules). While the presented findings are characteristic for reflux nephropathy, they are not pathognomonic: they also occur, for example, in urinary tract obstructions without reflux mechanism.

Familial pelviureteric junction hydronephrosis and its association with a duplex pelvicaliceal system and vesicoureteric reflux. A family study

The incidence of pelviureteric junction (PUJ) hydronephrosis and a bifid pelvicaliceal collecting system was determined in the parents and siblings of 19 patients with PUJ hydronephrosis. The high incidence of hydronephrosis in first degree relatives supports the hypothesis that PUJ hydronephrosis is inherited by an autosomal dominant gene of variable penetrance. There is a genetic inter-relationship between PUJ hydronephrosis and a bifid pelvicaliceal system and therefore indirectly between vesico-ureteric reflux and paraureteric diverticula. Ultrasound screening of the children of adults with PUJ hydronephrosis may lead to earlier diagnosis and treatment, thus preventing renal damage.

Vesicoureteric reflux: segregation analysis

Complex segregation analysis was applied to data from 88 families containing at least one person with vesicoureteric reflux. Analysis showed that a single major locus was the most important causal factor in this condition, with the mutant allele being dominant to the normal allele and having a gene frequency of about 0.16%. Forty-five percent of gene carriers will have vesicoureteric reflux and/or reflux nephropathy as adults and 15% will develop renal failure, compared to 0.05% and 0.001%, respectively, for those not carrying the gene. This analysis confirms the importance of screening close relatives of persons with proven vesicoureteric reflux or reflux nephropathy.

Congenital hypertrophic pyloric stenosis and associated anomalies in the genitourinary tract

Genitourinary anomalies were looked for in patients with congenital hypertrophic pyloric stenosis. In a prospective series of 64 patients investigated by intravenous pyelography, 13 were abnormal (20.6%). In a retrospective series of 232 patients, 6 had anomalies of the upper urinary tract (2.7%). In this latter series the incidence of inguinal hernia (3.4%), undescended testes (3.0%), and hypospadias (0.9%) was determined. In another 10 patients urinary tract anomalies (5), urinary infection (2), and a significant family history (3) were found associated with congenital pyloric stenosis. As the incidence of these anomalies is greater than expected, which suggests an interrelationship, a hypothesis has been proposed linking genetic factors and the metabolism of gastrin with the etiology of congenital hypertrophic pyloric stenosis.

The paraureteric diverticulum in childhood

The clinical features and the results of surgical treatment in 27 children with a paraureteric diverticulum treated between 1969 and 1979 were reviewed. The condition is commoner in males. Vesicoureteric reflux and double ureters were associated findings and together with the diverticulum accounted for the high incidence of urinary infection as a presenting feature. In only 2 patients with the diverticulum seen on excretion urography, but micturating cystography confirmed the diagnosis in 24 patients. Conservative treatment with continuous chemotherapy is satisfactory when the diverticulum is small and prior to the development of vesicoureteric reflux. In the later stages, excision of the diverticulum and reimplantation of the contiguous ureter is the surgical treatment of choice.

The interrelationship between paraureteric diverticula, vesicoureteric reflux and duplication of the pelvicaliceal collecting system: a family study

The incidence of a bifid pelvicaliceal system, vesicoureteric reflux, its sequelae and paraureteric diverticulum was determined in the patients and siblings of 22 patients with a paraureteric diverticulum. The results support the hypothesis that there is a direct genetic relationship between a paraureteric diverticulum, duplication of the pelvicaliceal system and vesicoureteric reflux. This suggests that the vesicoureteric reflux associated with a parauretic diverticulum is primary and related to lateral ectopia of the ureteric orifice. This syndrome complex may be inherited by multiple genes producing a cumulative effect, thus determining the length of the intravesical ureter, or by an autosomal dominant gene of variable penetrance.

A family study of vesicoureteric reflux

Vesicoureteric reflux is now considered to be due essentially to congenital malformation of the vesicoureteric junction. It is also considered to be a major cause of renal failure in early adult life. The condition is associated with recurrent urinary tract infection and in some instances with renal scarring. When reflux is detected clinically, in the investigation of patients with recurrent urinary tract infection, renal scarring is often already present. The reflux tends to disappear in later childhood.

A family study has been made based on 186 index patients with established primary reflux, with special attention to a history of genitourinary symptoms in the sibs and parents of these patients. There were 39 sibs under the age of 4 years. For these the parents were offered investigation by micturating cystogram. The parents of 20 accepted. Reflux was shown in 3, and in 2 of these there was already renal scarring. The proportion of all infants and young children who have reflux is not accurately known, but the few published surveys of screening of normal infants and young children by micturating cystogram suggest that the prevalence is of the order of 1%. The prevalence in sibs is, then, about 10 times higher. There was a main group of 214 sibs over the age of 4 years. For these the parents were offered investigation by intravenous pyelogram only for those sibs who had a history of recurrent urinary tract infection. If renal scarring was found then a micturating cystogram was done. Of 110 sisters, 12 were `symptomatic', renal scarring was found in 5 of these (1 was on haemodialysis), and reflux was still present in 3. Of 104 brothers 7 were `symptomatic', renal scarring was found in 2 and reflux was present in both. For comparison, the published reports of several surveys of schoolgirls indicate that about 2 in 100 have recurrent urinary tract infection, and in about a quarter of these (0·5%) reflux was present and in about one-eighth (0·25%) renal scarring was present. The prevalence in sibs is, then, 10 to 20 times higher. Similarly in the parents: of 183 mothers 7 (1 was on haemodialysis) and of 181 fathers 2 had renal scarring.

The family findings are consistent with multifactorial inheritance, as with other common malformations.

Routine investigation, in infancy, of younger sibs of patients with vesicoureteric reflux would identify patients in whom the reflux was recognised very early. These would be valuable for the study of the natural history and management of the disorder, and the degree to which it was possible to prevent the development of renal scarring.