Misplaced and Fused Human Kidneys

Not everyone’s kidneys sit neatly in the mid-torso under the ribcage, and their position can vary widely. During fetal development, the kidneys form in the pelvis and normally move upward, but in some people this migration fails, leaving them near the bladder, higher near the lungs as a thoracic kidney, or even both on the same side. In other cases, the two kidneys fuse together into a single mass known as a horseshoe kidney when they join during development. Most people never notice these differences because the kidneys often function normally, and the condition is usually discovered incidentally during scans or routine medical tests.

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