Rarely occurring at birth, crossed renal ectopia is an abnormality in which both kidneys occupy the same side of the body while one ureter - its length based on kidney location - traverses across midline to graft into opposite-side bladder.

McDonald and McClellan classified renal ectopia into 4 types.

Solitary crossed renal ectopia (SCRE) is an extremely uncommon abnormality of the urinary system. To date, only 35 instances have been documented in published literature. Typically, these cases are detected by chance during patient assessments for related issues such as genitourinary, cardiovascular, hematological or vertebral abnormalities.

Renal ectopia

Congenital malformation

Congenital single kidney

Renal lithiasis

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