ectopic kidney ectopic kidney ectopic kidney describes a kidney that is not located in its usual position. it results from the kidney failing to ascend from its origin in the true pelvis or from a superiorly ascended kidney located in the thorax. ectopic kidneyother namesrenal ectopiaectopic crossed fused kidney in a fetus approx. 34 weeksspecialtynephrology it has an incidence of approximately 1/900.