Fig. 1

Illustration of the renal anatomy of the nine cases of supernumerary kidneys, derived from the abdominal imaging available for each individual patient. SK posterior to the bladder (Case 1; a); SK anterior to the upper pole of the ipsilateral kidney, sharing a common ureter (Case 2; b). SK cranial and lateral to the right kidney (Case 3; c; Fig. 2a and b). SK located posterior to the bladder (Case 4; d). SK cranial to the right seminal vesicle (Case 5; e). SK located posterior and cranial to the bladder, as an inferior crossed ectopia from left to right (Case 6; f). SK located caudal to the right kidney, sharing a ureter fissus (Case 7; g). SK was cranial to the left kidney, with a ureter fissus to the hydronephrotic IK (Case 8; h). SK located cranial and posterior to the bladder (Case 9; i)