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CLINICAL IMAGE Table of Contents  
Ahead of print publication
Fused supernumerary kidney with nephrolithiasis: Incidental detection of a rare anomaly

 Department of Radiology, St. John's Hospital, Bengaluru, Karnataka, India

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Date of Submission28-Jan-2022
Date of Decision22-Mar-2022
Date of Acceptance27-Apr-2022
Date of Web Publication07-Jun-2022

How to cite this URL:
Reddy R. Fused supernumerary kidney with nephrolithiasis: Incidental detection of a rare anomaly. Apollo Med [Epub ahead of print] [cited 2022 Sep 27]. Available from: https://apollomedicine.org/preprintarticle.asp?id=346897

  Description Top

A 28-year-old female presented to the casualty with a 3-month history of abdominal pain localized to the right lumbar region, for which she had been taking nonsteroidal anti-inflammatory drugs. Physical examination revealed no abdominal tenderness. Ultrasonography findings of the abdomen revealed the right kidney measuring 9.9 cm × 1.1 cm with evidence of a calculus measuring 22 mm in the superior pole region [Figure 1]. There were no anatomical variations related to renal arteries and veins. However, there is fusion of cranially placed native kidney measuring 8.3 cm × 3.7 cm, with the caudally placed supernumerary kidney which measures 8.0 cm × 3.5 cm. The kidneys demonstrate partial fusion with evidence of parenchymal bridging between both the kidneys [Figure 2]. The differential diagnosis considered was a duplex kidney.
Figure 1: Ultrasonography image demonstrating native right kidney with evidence of a calculus in the superior pole region

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Figure 2: Ultrasonography image demonstrating lower supernumerary kidney located below and demonstrating fusion with the native left kidney. Note the hypoechoic parenchymal bridge between both the kidneys

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  Discussion Top

Supernumerary kidney is a rare entity, which is commonly left sided, may be smaller in size, and is caudally placed as compared to native kidney.[1] The more common duplex kidney is considered in the differential diagnosis which demonstrates duplex collecting system with either a single, partially fused, or nonfused bifid ureter.[2] A bifid ureter is commonly associated with supernumerary kidney.[3] The main difference is that supernumerary kidney has a separate pelvicalyceal system with a distinct renal capsule, native arterial supply and venous drainage. Supernumerary ureter usually follows Weigert-Meyer law in cases of double ureters like duplex kidneys. Most of the supernumerary kidneys are on the left and usually caudal to the native kidney. Mostly, the accessory kidney is smaller in size with reduced excretion. Rarely, the ectopic ureteral opening of the supernumerary kidney may insert into the vagina and may then present with complaints such as urinary incontinence.[4] Supernumerary kidney has an association with multiple anomalies such as coarctation of the aorta, ventricular septal defects, horseshoe kidney, vaginal atresia, imperforate anus, and meningomyeloceles.[5] Supernumerary kidney is also more prone to complications such as nephrolithiasis and obstructive uropathy. The evaluation of supernumerary kidney may be done by ultrasound, intravenous urography, computed tomography, magnetic resonance imaging, and nuclear medicine studies like dimercaptosuccinic acid and diethylenetriamine pentaacetate (DTPA) scans. Ultrasound is useful in morphological characterization while the rest may aid in the functional assessment too. In conclusion, unmitigated description of imaging features such as position, number, orientation, vascularity, and the status of the ureter is necessary while dealing with supernumerary kidney, in the event when surgical procedure may be necessitated to address complications such as hydronephrosis, pyelonephritis, obstructive uropathy, and urothelial carcinoma.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Al Dandan O, Hassan A, Almutairi A, Alakloby E, Fadaak K. Malrotated right supernumerary kidney: Case report of a rare anomaly. Urol Case Rep 2019;26:100966.  Back to cited text no. 1
Jamshidian H, Tavakoli K, Salahshour F, Nabighadim A, Amini E. Supernumerary kidney associated with horseshoe malformation: A case report and review of literature. Urol Case Rep 2017;11:57-9.  Back to cited text no. 2
Vakade AD, Sudin SR, Sasidharan K, Jayasudha S. Supernumerary kidney forming isthmus of horseshoe kidney: A rare presentation. Indian J Urol 2020;36:138-9.  Back to cited text no. 3
  [Full text]  
Rehder P, Rehwald R, Böhm JM, Grams AE, Loizides A, Pedrini M, et al. Supernumerary kidneys: A clinical and radiological analysis of nine cases. BMC Urol 2019;19:93.  Back to cited text no. 4
Janda GM, Nepple KG, Cooper CS, Austin JC. Supernumerary kidney in a child with OEIS complex. Urology 2009;74:305-7.  Back to cited text no. 5

Correspondence Address:
Ravikanth Reddy,
Department of Radiology, St. John's Hospital, Bengaluru - 560 034, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/am.am_16_22


  [Figure 1], [Figure 2]


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