What is the term for kidneys that fail to ascend into their normal position?

The term for kidneys that fail to ascend into their normal position is "ectopic kidney." This condition occurs when one or both kidneys remain in an abnormal location, typically situated lower in the abdomen or in the pelvis, rather than moving to their usual position in the upper abdominal cavity during fetal development.

In normal development, kidneys typically ascend from their original position in the pelvis to their final location in the upper abdomen. If this ascent is disrupted, the result is an ectopic kidney, which can sometimes lead to complications such as urinary obstruction or vascular impairment due to their atypical positioning.

Other terms listed involve different renal anomalies: "pelvic kidney" is a specific type of ectopic kidney located in the pelvis, "renal agenesis" refers to the absence of one or both kidneys, and "unilateral kidney" typically describes the presence of one functional kidney without implying positional anomalies. Thus, while these terms pertain to renal abnormalities, they do not accurately describe kidneys that have failed to ascend, which is specifically covered by the term ectopic kidney.