RENAL DUPLICATION AND FUSION ANOMALIES

doi:10.1016/S0031-3955(05)70559-9

Pediatric Clinics of North America

Volume 44, Issue 5, 1 October 1997, Pages 1323-1341

https://doi.org/10.1016/S0031-3955(05)70559-9 Get rights and content

Renal duplication is a common occurrence, and the range of ureteral and renal anomalies draining the two poles of the duplex kidney leads to a variety of interesting clinical presentations with which practicing pediatricians need to be familiar. Renal fusion anomalies present less frequently, and, although they are often asymptomatic, their implications in children are important to understand.

Confusion in the nomenclature describing kidneys drained by two ureters led to the Committee on Terminology, Nomenclature and Classification of the American Academy of Pediatrics Section on Urology to propose terminology that has become generally accepted and standardizes the description of these systems.¹² A duplex or duplicated system is defined as a kidney that has two pyelocalyceal systems. In patients with partial or incomplete duplication, either a single or bifid ureter is present; in patients with complete duplication, two ureters are present that empty separately into the bladder.

The two ureters associated with complete duplication are termed double ureters, and the upper or lower pole ureter describes the ureter that drains the upper or lower pole of a duplex kidney. The orifice associated with the upper pole ureter (UPU) is called the upper pole orifice, and that associated with lower pole ureter (LPU) is the lower pole orifice. A normal ureteral orifice inserts on the trigone of the bladder. A ureteral orifice is laterally ectopic if it is situated lateral to the normal position and medially or caudally ectopic if it is situated on the proximal lip of the bladder neck or beyond. An ectopic ureter drains to an abnormal site, but by widely accepted common usage, the committee agreed that the term ectopic ureter would describe a ureter in which the orifice is medially or caudally ectopic.

A ureterocele is an anomaly in which the distal intravesical portion of a ureter is dilated. If the ureterocele is located totally within the bladder, it is termed intravesical; if a portion of the ureterocele is permanently located at the bladder neck or in the urethra, it is termed ectopic. This terminology is used in the description of the anomalies described in this article.

Section snippets

EMBRYOLOGY

An understanding of the embryology of ureteral development is helpful when trying to sort out the common variants of ureteral duplication. Although some lesions are readily accounted for by currently accepted theories of ureteral development, some are not completely understood. Ureteral duplication and the abnormalities of ureteral insertion are easily explained if one comprehends the following description of normal ureteral origin and insertion.

The normal ureter arises as a bud or diverticulum

URETERAL DUPLICATION

Ureteral duplication may be incomplete or complete. Incomplete duplication implies that there is a bifid collecting system; if the two pyelocalyceal systems join at the ureteropelvic junction (UPJ), a bifid pelvis exists, and if the two ureters join at a point below the UPJ but before entering into the bladder, the patient has bifid ureters. Two separate ureteral orifices enter the bladder in patients with complete ureteral duplication. Complete duplication may be complicated by a variety of

URETERAL DUPLICATION WITH VESICOURETERAL REFLUX

In a clinical series of 100 consecutive children requiring surgery for problems associated with renal duplication, Barrett and colleagues¹ found that 63 children underwent surgery because of vesicoureteral reflux (VUR) associated with their duplex system (Fig. 3). All of the children had reflux into the LPU, and 11 had concomitant upper pole reflux. Most series confirm that the finding observed most frequently in children evaluated for urinary tract infection (UTI) who have complete duplication

DUPLICATION WITH ECTOPIC URETER

If a ureteral bud originates at a more craniad position than normal on the mesonephric duct, the ureter migrates for a longer period along the path that the mesonephric duct follows before it is actually absorbed onto the bladder. When the ureter finally separates from the mesonephric duct, it will have been carried medial and caudad to its normal site of ureteral insertion. If it does not separate from the mesonephric duct, the ureter terminates in a structure derived from the mesonephric

URETEROCELES

A ureterocele is a cystic dilatation of the submucosal or intravesical ureter. A ureterocele may subtend a single system or the UPU of a duplex system. Ureteroceles rarely occur at the end of a LPU.

Reported incidence of the ureteroceles on autopsy series varies between 1 in 500 to 1 in 4000. Clinically, girls are affected more commonly than boys with a 3- or 4-to-1 predominance. The left side is affected more frequently than the right. Ureteroceles are bilateral in approximately 10% of cases.

HORSESHOE KIDNEY AND OTHER RENAL FUSION ANOMALIES

Clinical problems associated with renal fusion anomalies occur infrequently in pediatric urologic practice. These anomalies, however, do predispose to infection; hydronephrosis; stone disease; and, in some cases, neoplasia; therefore, an overview of these conditions is important.

The ureteral bud originates from the mesonephric duct and extends toward the metanephric blastema during the fourth and fifth weeks of gestation to induce the kidney. During normal development, the kidneys ascend and

SUMMARY

Renal duplications and fusion anomalies in children often present challenging problems. The diagnostic evolution of these entities often consists of upper tract imaging to evaluate function and help diagnose obstruction, and lower tract imaging to assess reflux and at times voiding dynamics. The clinician needs to be aware of the variable presentations of these lesions, their evolution, and the therapeutic interventions that may be required to resolve problems resulting from them.

References (37)

D.M. Barrett et al.
Problems and solutions in surgical treatment of 100 consecutive ureteral duplications in children
J Urol
(1975)
B. Blyth et al.
Endoscopic incision of ureteroceles: Intravesical versus ectopic
J Urol
(1993)
D.L. Boatman et al.
Congenital anomalies associated with horseshoe kidney
J Urol
(1972)
D. Buntley
Malignancy associated with horseshoe kidney
Urology
(1976)
A.A. Caldamone et al.
Ureteroceles in children: Followup of management with upper tract approach
J Urol
(1984)
D.E. Coplen et al.
The modern approach to ureteroceles
J Urol
(1995)
G.W. Friedland et al.
Renal ectopia and fusion: Embryologic basis
Urol
(1975)
K.I. Glassberg et al.
Report of the Committee on Terminology, Nomenclature and Classification, Section on Urology, American Academy of Pediatrics: Suggested terminology for duplex systems, ectopic ureters and ureteroceles
J Urol
(1984)
P.E. Gleason et al.
Hydronephrosis in renal ectopia: Incidence, etiology and significance
J Urol
(1994)
D.A. Husmann et al.
Ureterocele associated with ureteral duplication and a nonfunctioning upper pole segment: Management by partial nephroureterectomy alone
J Urol
(1995)

D.J. Jones et al.

Percutaneous nephrolithotomy for calculi in horseshoe kidneys

J Urol

(1991)

P. Lee et al.

Duplex reflux: A study of 105 children

J Urol

(1991)

D.R. Locke et al.

Extracorporeal shock-wave lithotripsy in horseshoe kidneys

Urology

(1990)

G.G. Mackie et al.

Duplex kidney: A correlation of renal dysplasia with position of the ureteral orifice

J Urol

(1975)

J. Mandell et al.

Ureteral ectopia in infants and children

J Urol

(1981)

G. Monfort et al.

Surgical management of duplex ureteroceles

J Pediatr Surg

(1992)

W.R. Pitts et al.

Horseshoe kidneys: A 40-year experience

J Urol

(1975)

J.W. Segura et al.

Horseshoe kidney in children

J Urol

(1972)

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Duplex kidneys may be associated with additional pathologies with an indication for surgery. Various surgical approaches have been described. However, little is known about long-term outcomes and quality of life (QoL) for these patients.
To present long-term outcomes and QoL data up to 30 yr after surgical treatment of duplex kidneys and associated pathologies.
We collected clinical and operative data for all patients who underwent surgery for complicated duplex kidney at our institution from 1990 to 2018. All patients were invited for a follow-up examination or telephone interview.
We evaluated renal function, clinical outcomes, residual dilation of the upper urinary tract, and health-related QoL.
Of the 176 patients included, 173 were available for follow-up (mean 140.5 mo). Surgical treatment involved an upper-tract, lower-tract, or combined approach in 11%, 56%, and 33% of cases, respectively. Rates of perioperative complications (8%) and secondary surgery (10%) were low. Overall, 95% of our patients achieved full restitution. Renal function was preserved in all cases, with recurrent urinary tract infections reported by just 2% and urinary incontinence by 1%. Good health-related QoL was reported by 98% of patients. Those without full restitution included six patients who underwent total nephrectomy and two boys who underwent multiple surgeries and urinary diversion. Our results are limited by their retrospective nature, including partly incomplete data sets.
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Almost all patients undergoing surgery for duplex kidneys and associated pathologies will lead a life without body impairment and good quality of life.
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Citation Excerpt :
We performed our analysis in terms of kidney number rather than pelviureteral units because of the inability to accurately determine the total number of completely duplicated kidneys based on US, ceVUS and/or VCUG results. Most duplex kidneys are not associated with VUR, and US alone cannot detect all duplex kidneys or determine the degree of duplication (i.e., partial or complete), even when a duplex kidney is thought to be present [14,15]. Additional findings noted in the original VCUG reports were compared to additional findings recorded by each rater on retrospective review of the ceVUS studies.
There is limited quality of evidence regarding the accuracy of contrast-enhanced voiding urosonography (ceVUS) for diagnosis of vesicoureteral reflux (VUR) compared to fluoroscopic voiding cystourethrography (VCUG), and minimal data on the use of the ultrasound contrast agent Optison™ for this purpose.
To compare the accuracy of ceVUS using Optison™ to VCUG, and to assess inter-rater agreement regarding presence and grading of VUR.
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97 children (51 females) with 101 paired studies were included. Sensitivity and specificity of ceVUS for VUR detection were identical for both raters: right kidney 75%/90.9%; left kidney 85.7%/78.9% (Figure). There was no statistically significant difference in disagreement between raters and the VCUG report for the right or left kidney. Inter-rater agreement on ceVUS grading was 90% and 88% for right and left kidneys, respectively. There was a significant negative association between fetal hydronephrosis vs urinary tract infection and disagreement between Rater 2 and the VCUG report for the left kidney. There were no other significant associations with respect to either kidney, Optison™ dose, or referral diagnosis.
Our study showed that detection of VUR with ceVUS and Optison™ is comparable to fluoroscopic VCUG. Based on the VCUG reports, the incidence of VUR in our patient population was substantially lower than in the meta-analysis of Chua et al. and in the study of Kim et al. The explanation for the large discrepancy in VUR incidence may reflect differences in the patient populations, and in our reporting of VUR with respect to kidney number rather than to pelviureteral units. Study limitations include its retrospective nature and potential bias in terms of patient selection. Since VUR is an intermittent phenomenon, sequential rather than simultaneous performance of the ceVUS and fluoroscopic studies might have influenced VUR detection.
A blinded comparison of ceVUS performed with Optison™ to fluoroscopic VCUG showed moderate-good sensitivity and specificity for diagnosis of VUR.
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There are three abnormalities of kidney location: simple renal ectopia or pelvic kidney, crossed renal ectopia, and horseshoe kidney. Simple renal ectopia is a kidney that is located on the correct side but in the pelvis, with the adrenal gland filling the renal fossa. With crossed renal ectopia, both kidneys are on the same side; one kidney is in the normal location and the other is located just below the first, with its ureter crossing the midline before inserting into the bladder. Horseshoe kidney indicates fusion of the inferior poles of the kidneys in the midline to form a horseshoe shape. Renal ectopia tends to be more challenging to detect prenatally than other renal abnormalities, particularly horseshoe kidney. Each type of ectopia is associated with increased risk for vesicoureteral reflux and ureteropelvic junction obstruction. Third-trimester evaluation is suggested, even in the absence of renal pelvis dilatation earlier in gestation. There is also a high prevalence of anomalies of other organ systems, and if any associated anomalies are identified, amniocentesis should be offered.

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: Address reprint requests to Ross M. Decter, MD, The Milton S. Hershey Medical Center, The Pennsylvania State University, 500 University Drive, Hershey, PA 17033

^*: From the Department of Pediatric Urology, The Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, Pennsylvania

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