helpsimple searchclear selectionselect all
Dictionary assisted search
All words
Any word/input
Exact phrase
in these
lexical topics:
  • Physics, Techniques and Procedures
  • Normal Anatomy
  • Musculoskeletal Imaging
  • Breast Imaging
  • Gastrointestinal Imaging
  • Urogenital Imaging
  • Chest Imaging
  • Cardiovascular Imaging
  • Neuroradiology
  • Head and Neck Imaging
  • Paediatric Imaging
 
 
 
Urogenital Imaging

Supernumerary kidney

When the total number of kidneys exceeds two, supernumerary kidneys are present. Supernumerary kidneys may refer to more than two separate kidneys, or to a horseshoe kidney with one or more additional kidneys. They function normally, have a normal shape and capsule, and are either not attached to or loosely attached to the normal kidney. They are relatively rare, and when they do occur they usually have no clinical significance. Males and females are equally affected. Although commonly smaller than the usual kidney, and in an abnormal location, a supernumerary kidney may be the same size or larger. It may be located in front of, below, above or behind the usual kidney. Supernumerary kidneys have either a separate ureter or bifed ureters, and a variety of urinary drainage patterns. Although there are many hypotheses about the embryological events which produce supernumerary kidneys, no single theory has been proven. Some theories postulate that the metanephrogenic blastema divides, giving rise to a separate kidney. Others suggest that the ureteric bud divides prematurely or that two buds come off the Wolffian duct.

Intravenous urography may show the complete additional kidney as well as the abnormalities in size and location. Additional imaging studies are needed to determine whether the kidneys are separate or fused. CT is a practical, useful and accurate modality in the diagnosis of supernumerary kidney and in addition, in assessment of whether the kidneys are separated or fused.

HH