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Purpose: To determine the value of fetal magnetic resonance imaging (MRI) to detect renal duplication.Methods: In this retrospective study, prenatal MRI and ultrasound (US) diagnoses were compared ...

Objectives: To report on long-term follow-up and outcomes of infants and small children who have undergone laparoendoscopic single-site (LESS) partial nephrectomy to manage upper urinary tract dupl...

A duplication artefact is sometimes encountered on ultrasound examination of the left kidney. It is caused by sound beam refraction between the spleen and adjacent fat. The purpose of this study was to analyse the frequency and types of such artefacts, and examine their physical background. The examiner searched for a left renal duplication artefact in 150 unselected abdominal ultrasound studies. A disturbed contour of the left kidney could be formed in 34 of 123 patients in whom the spleen was in the image without covering the kidney completely. An artefact was seen significantly more often when the lower pole of the spleen was rounded (30/87) than when it was wedge shaped (4/36) (p0.02). The artefacts could be categorized into complete upper pole duplication (n = 4), incomplete upper pole duplication (n = 14) and bayonet artefact (n = 16). The thickness of the renal cortex appeared reduced with upper pole duplication artefacts owing to a geometric image compression, which could also be seen in an in vitro experiment. Left renal duplication artefacts are not rare when the upper part of the kidney is examined by ultrasound through the spleen.

Renal duplication is the most common malformation of the urinary tract and is frequently seen among children with urinary tract infection (UTI).To evaluate problems in the interpretation of dimercaptosuccinic acid (DMSA) scintigraphy and to establish the range of relative function in uncomplicated unilateral duplication.Retrospective analysis of 303 children less than 2 years of age with first time non-obstructive urinary tract infection investigated by both urography and DMSA scintigraphy. At DMSA scintigraphy, renal lesions and/or relative function below 45% was considered abnormal. Urography was used as reference for the diagnosis of duplication.Duplex kidneys were found in 22 of 303 patients (7%). Of the 16 children with unilateral duplication, 10 had bilaterally undamaged kidneys with a range of relative function varying between 51% and 57% in the duplex kidney. In two of the children with unilateral duplication the imaging results were discordant.There was risk of underdiagnosis as well as overdiagnosis of renal damage at scintigraphy. Although it is important to be aware of this risk, the rate of misinterpretation was low. A range of 51% to 57% can be used as the limit for normality of the relative function of a unilateral duplex kidney.

The Weigert–Meyer rule predicts the draining pattern of duplex ureters in bipolar renal duplications. This paper introduces two cases of nonpolar renal duplication. A 3-month-old and a 15-year-old female with history of urinary tract infection were evaluated with intravenous pyelograms (IVP) and eleven different parameters were analyzed. The infant’s IVP showed an unobstructed side-to-side right renal duplication with normal-sized nondisplaced lateral moiety and a complete set of calyces, without drooping lily sign. The nonobstructed moiety projected medial and mildly inferior to the lateral moiety which had normal height and axis. The ureters joined each other in lower abdomen. Severe platyspondyly was noted due to hyperalimentation-induced metabolic bone disease. The second case had an unobstructed interpolar extra moiety between the upper and the lower poles with an otherwise unobstructed, normally sized single-system kidney, without drooping lily sign. The paradigm shift from classic anatomic to contemporary cell biological theory validates the nonpolar renal duplication concept, with side-to-side and interpolar arrangements of the moieties, in defiance of Weigert–Meyer rule.

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.

An extremely rare incomplete duplex system with cystic dilatation of the upper part of the conjoint ureter presenting as hydronephrosis in a 2-year-old infant is reported.

The child with ectopic ureterocele frequently presents a diagnostic challenge. The use of standard excretory urography combined with newer modalities, such as ultrasonography and radionuclide renal scanning, provides an orderly diagnostic approach to ectopic ureterocele. This integrated approach should ensure the highest yield in a diagnostic sense and aid in assessing upper tract function, thus, helping with the selection of the proper surgical management.

We have seen 5 children with a non-obstructive ectopic ureterocele associated with an undilated upper pole collecting system. Thus the telltale signs of renal duplication found with obstruction of the upper pole were absent. Cystoscopy confirmed the diagnosis when retrograde injection of the ureterocele outlined a narrow ureter and small dysplastic kidney. Because reflux usually was present in the ipsilateral lower pole ureter (86 per cent) surgical treatment consisted of excision of the ureterocele and common sheath ureteral reimplantation. Removal of the small non-functioning upper renal segment was not necessary in most instances. The embryology of this anomaly is discussed.

The diagnoses of complete obstruction in a duplicated renal collecting system and ureterocele can be made with a high degree of confidence by ultrasound. Two children presenting with abdominal masses were examined by gray scale ultrasonography which demonstrated large cystic masses dorsal to and displacing the lower pole of the kidney ventrally and laterally. In one patient the dilated ureter terminated in a ureterocele. Ultrasonography is the appropriate imaging modality for this disease process, though it generally becomes the complementary study to excretory urography in the diagnosis of an obstructed duplicated system. The dilated pelvis and ureter can be imaged to ultrasonography even when their presence is only implied on an excretory urogram. Finally, the cystic nature of a ureterocele, as well as its relationship to the ureter and bladder, makes ultrasonography an ideal technic for evaluating this anomaly.

Absolute kidney length and the ratio of right to left kidney lengths were estimated by the method of Eklof & Ringertz in a series of 142 patients with unilateral renal duplication. The anomalous kidney was frequently found to be larger than the contralateral one, particularly when associated with ectopic ureterocele, which was present in 34 patients. Nevertheless, a substantial number of reduplicated kidneys had a length below mean, some of them actually below -2SD.

To determine the appearance of artifactual renal duplication in ultrasound (US) imaging, the authors analyzed 22 examples of such duplication in 20 patients. The artifact appeared as a duplication of the collecting system in 18, as a suprarenal mass in three, and as upper-pole cortical thickening in one. It occurred in the left kidney in 15 patients, in the right kidney in three, and bilaterally in two. To determine the frequency of the artifact, 50 additional patients were scanned. It was identified in eight of these patients. Imaging characteristics and the results of in vitro modeling proved the artifact was due to sound beam refraction between the lower pole of the spleen or liver and adjacent fat. This artifact is much more common in the left kidney and occurs more frequently in obese patients. Knowledge of the appearance and cause of this artifact should help radiologists avoid diagnostic errors.

On the basis of previous studies in rats, and clinical observations in human renal transplantation and in patients with a renal duplication anomaly, we have postulated two distinct types of renal growth. Compensatory growth is caused by a nephron deficit, while obligatory growth is part of the normal process of growing into adulthood. The former is reversible, and the latter is not. A definitive test of this hypothesis required the transplantation of extra kidneys into baby rats and comparison of their growth with that of normal litter-mate controls. This showed that there is little if any retardation of obligatory renal growth in spite of the presence of an excess of kidneys in the baby.

Delineation of the presence and anatomy of an obstructed, nonfunctioning upper-pole duplex system often requires multiple imaging techniques. Computed tomography (CT) was used to evaluate duplex systems in five adult patients. Independent of renal function, CT allowed assessment of the presence of a duplex system, determination of whether the system was obstructed, assessment of the quantity of residual parenchyma in the upper-pole system, determination of whether the ectopic ureter was intravesical or extravesical, and assessment of the retroperitoneum to look for unusual causes of upper-pole ureteral obstruction.

Neonatal adrenal hemorrhage can usually be diagnosed on excretory urography without resorting to surgical exploration or invasive diagnostic procedures. In the typical case an avascular mass is seen between the liver and kidney. A case is presented in which a vascular rim surrounded the avascular mass, giving an appearance similar to that of an obstructed upper pole renal duplication. This early vascular rim, not as well known as the calcified rim which develops days to weeks after the acute hemorrhage, is probably created by compression and displacement of adrenal tissue by the central hemorrhage.

The rare finding of lower pole ureteropelvic junction obstruction and incomplete renal duplication is discussed in 5 children. The children were divided into 2 groups, with short (less than 0.5 cm.) and long (greater than 4 cm.) lower ureteral segments. Short ureteral segment obstruction was managed by total excision of the narrow ureteral segment and end-to-side pyeloureterostomy. Obstructions associated with long lower ureteral segments were treated by excising the ureteropelvic junction and performing a standard Anderson-Hynes pyeloplasty. A thorough preoperative evaluation is helpful for successful management.

Renal duplication with a nonfunctioning hydronephrotic segment may lead to diagnostic difficulty and misinterpretation as tumor or cyst. Selective renal arteriography is an important adjunct to the diagnosis in such cases. The finding of a deficient arterial supply and a poor nephrogram phase in an area with no visible collecting system should suggest the diagnosis.

SUMMARY A case of bilateral complete duplication of kidneys and ureters in a child is described. She presented with enuresis since infancy, and this disappeared following removal of the upper part of the right kidney together with its related pelvis and ureter and the control of the E. coli infection with chloramphenicol. It is seven months since operation but too early to consider her cured. In this child intravenous pyelography and cystoscopy did not show the exact type of anomaly.

Renal duplication is not an uncommon anomaly of the urinary tract. However, we report a case in which the occurrence of incomplete duplication of a large lower pole, with an unusual side-by-side orientation of the lower pole segments, delayed recognition of the clinically troublesome ipsilateral upper pole duplication.

Herein is reported a case in which congenital ureteropelvic obstruction was complicated by renal duplication. A dismembered pyeloplasty requiring two anastomoses was performed.