Ectopic Kidneys

Defects in embryological renal development may lead to ectopic or maldeveloped renal systems. At the risk of oversimplification, the kidneys may be thought of as developing in the embryo as one structure in the 'pelvic' area, migrating upwards and separating with growth.

Failure in normal development may result in failure of the kidneys to migrate normally and indeed they may fail to separate. This results in a 'pelvic kidney' when one or both remain in the pelvis, a 'crossed ectopic kidney' when both have moved to the same side of the spine, a horseshoe or discoid kidney when there is partial (usually fusion of the lower poles) or total failure of separation.

In clinical practice the main problem associated with ectopic kidneys usually relates to impaired urinary drainage with secondary obstruction or stone formation. This may be compounded if infection supervenes, the poor drainage making eradication of infection difficult and predisposing to stone formation.

Pelvic kidneys may interfere with parturition. The ectopic kidney is generally sited in the pelvis although it may be found anywhere in the abdomen. In some instances an ectopic kidney may be fused to a normal kidney.

The initial function of the ectopic kidney is often normal. However patients with ectopic kidneys are often prone to reflux, obstruction and the development of urinary tract infections.