the real frequency of supernumerary kidney could not be computed due to its unusual appearance .
there are five cases presented in the literature ( 1 - 5 ) . in embryogenesis ,
the atypical section of nephrogenic cord into two metanephric blastemas with bifurcation of one bud shapes supernumerary kidneys .
genuinely , supernumerary kidney that is an accessory organ has its own collecting system , blood supply , and separate encapsulated tissue . the supernumerary kidney may be completely distinct from the usual renal tissue or linked to it by loose connective tissue ( 6 , 7 ) . in our case ,
we demonstrate radiological findings in a young man with bilateral supernumerary kidney on computed tomography .
a 23-year - old man was admitted to the endocrinology clinic with a one - year history of hypertension .
the color doppler study was performed , but the renal arteries were not shown because of gas artifact . then , abdominopelvic computed tomography ( ct ) examination ( somatom emotion duo ct , siemens , berlin , germany ) with 100 ml of nonionic intravenous contrast material ( ultravist 300 ; schering , germany ) was performed for differential diagnosis with the following scanning parameters : 0.6 mm collimation , 5 mm slice thickness , 1.4 mm increment , 100 kv , 135 mas , and a pitch of 0.9 .
it was injected at a flow rate of 5 mm / second applying an automatic injector .
bilateral supernumerary kidneys were demonstrated on ct ( figure 1 a - c ) . on each side
a significant rotation anomaly was found at the inferiorly located kidneys that were smaller than the superiorly located kidneys on each side .
the collecting system of all four kidneys was expanded ( figure 2 ) . on each side , there were two renal arteries that originated from the aorta ( figure 3 and 4 ) .
a conservative approach was decided with regular follow - up including urine and blood analysis and us .
a , coronal b , right sagittal and c , left sagittal mpr reconstruction of contrast enhanced ct images demonstrates bilateral supernumerary kidneys .
bilateral supernumerary kidney is an uncommon renal abnormality , which influences both genders evenly ( 8) .
it is commonly smaller , situated usually in the left quadrant and it may be placed in a caudal situation . the supernumerary kidneys may be established in the iliac or sacral region ( 9 ) .
a narrow stratum of fibrous structure may closely separate supernumerary kidneys or it is entirely discrete from the opposite side .
embryologically , the fundamental difference must discriminate the rare supernumerary kidney from the usual combined duplex systems .
a sprout diverges and every division permeates a freely mixed metanephric mesenchymal mass and bifid ureters in combined duplex bifid kidneys . once two sprouts originate disparately from the wolffian duct and permeate the similar metanephric mass , two free nephritic collecting structures shape , but the parenchymas abide blended .
a sprout divides into two and every division permeates separately a metanephric mass , which improves into unrelated simple kidneys in supernumerary kidneys with bifid ureters ( 6 , 10 ) .
the supernumerary kidney disagrees from the duplex kidney and megapolycalycosis in that its own divided parenchyma crowns each pelvicaliceal system ( 4 ) . in most of the patients with supernumerary kidneys ,
the ureter of the supernumerary kidney may have calculus disorder and hydronephrosis ( 11 ) .
supernumerary kidney may be cranial or caudal to the normal kidney . in our case ,
coarctation of the aorta , ectopic ureteral opening , duplication of the penis or female urethra , vaginal atresia and horseshoe kidneys are congenital anomalies associated with the supernumerary kidney ( 12 ) .
bilateral supernumerary kidney in conjunction with horseshoe anomaly was described by mustafa ( 5 ) .
oto et al . described bilateral supernumerary kidney with bifid ureters bilaterally in intravenous pyelography ( ivp ) ( 3 ) . in our case
a palpable abdominal mass , pain and fever are commonly the demonstrating symptoms ( 6 , 9 ) .
if there is no symptom in the patient with supernumerary kidneys , medical care is not needed and regular follow - up is suggested .
if renal disease is found , nephrectomy is advised ( 11 ) . associated with supernumerary kidneys ,
many complications such as pyelonephritis , stones , pyonephrosis , hydronephrosis , and malignant changes ( clear cell carcinoma , wilms tumor ) have been reported ( 11 , 13 ) . in our case , bilateral supernumerary kidney associated with hypertension was observed .
excretory urography , usg , ct , nuclear scintigraphy , and magnetic resonance imaging ( mri ) can be used for the diagnosis of supernumerary kidney .
in addition , they reported that mri can show the presence of individual ureters ( 14 ) .
it is hard to diagnose supernumerary kidney before operation and clinicians have not observed most cases preoperatively . on excretory urograms ,
it is difficult to identify supernumerary kidney since they are commonly smaller and have a decreased function ( 9 , 11 ) . on each side , in our case , ct had characteristic findings and obviously presented the combination of kidneys .
we think that ct commonly appears to be enough for the diagnosis of supernumerary kidneys .
ct angiography may be a useful radiological method to discover the compound anatomy of arteries in kidneys and to discern the origin of renal arteries non - invasively .
the use of mr angiography to detect the origin of renal arteries could be an alternative .
 to our knowledge , bilateral supernumerary kidney is a very rare renal abnormality and there are five cases presented in the literature . 
 it is difficult to diagnose supernumerary kidney and clinicians have not detected most cases preoperatively . 
 laboratory and imaging studies were acquired and carefully examined . 
 the normal laboratory tests were found . 
 emergency ultrasonography was performed and they revealed no signs of parenchymal abnormality in both kidneys . 
 serial imaging study including enhanced computed tomography ( ct ) was performed . 
 an imaging study identified bilateral supernumerary kidney with expanded collecting systems . on each side , significant rotation anomaly was found . 
 in addition , there were two different renal arteries originating from the aorta . 
 this report presents radiological determinations of supernumerary kidney bilaterally in a young man . 
 we think that ct commonly appears to be enough for the diagnosis of supernumerary kidneys . 
1. Introduction
2. Case Presentation
3. Discussion