Horseshoe kidney is the most common type of fusion anomaly with an incidence of 0.15% in the general population (Fig. In crossed-fused renal ectopia, the ectopic kidney crosses to the opposite side and fuses with the normal kidney. The ectopic kidney is usually located inferior to the normal kidney with fusion. 2012; 3123-360.]. It has varied presentation from incidental detection to renal impairment. Kelalis PP, Malek RS, Segura JW. Rubinstein ZJ, Hertz M, Shahin N, Deutsch V. Crossed renal ectopia: angiographic findings in six cases. There is a recognized male predominance with a 2:1 male to female ratio. Crossed-fused renal ectopia is a rare congenital abnormal development of the urinary system. AJR Am J Roentgenol 1976; 126:1035. J Urol 1973; 110:588. Cross fused renal ectopia is a rare anomaly with the estimated incidence is around 1 out of 1000 births 4). The exact cause of CRE is unknown. MCDONALD JH, MCCLELLAN DS. Crossed fused renal ectopia is a rare congenital malformation, wherein both kidneys are present unilaterally, with the ureter of the crossed kidney opening into the bladder on the contralateral side. Crossed fused renal ectopia is a rare congenital anomaly in which the kidneys are fused and are located on the same side relative to midline. Crossed renal ectopia. Crossed fused renal ectopia refers to an anomaly where the kidneys are fused and located on the same side of the midline. About 20% of patients with crossed renal ectopia also have VUR (Guarino et al., 2004), and ... crossed fused ectopia and even intrathoracic kidneys have been described. Crossed fused renal ectopia (CRE) is the second most common congenital fusion anomaly of kidney [2 Bauer BS et al. Horseshoe kidney. 33.21B). More than 90% of crossed renal ectopia results in fusion. Crossed fused ectopia of the kidneys TV Patel1 and AK Singh1 1Renal Division, Brigham and Women’s Hospital, Boston, Massachusettes, USA Correspondence: TV Patel, Renal Division, Brigham and Women’s Hospital, 75 Francis Street, Boston, Massachusettes, USA. Observations on renal ectopia and fusion in children. Am J Surg 1957; 93:995. Depending on the extent of fusion and the resulting shape of the fused renal mass, crossed fused ectopia can be subdivided into six subgroups. The first case was reported by Dominicus Panarolus in 1654, and today, it has an estimated prevalence of about 1 in 1000 live births with a 3:2 male to female predominance . Anomalies of form and fusion, crossed renal ectopia with and without fusion.Wein: Campbell-Walsh Urology Book 10th ed.