Expansion
You can get above a kidney and ballotte it; you cannot with a spleen
Expansion
| Feature | Kidney | Spleen |
|---|---|---|
| Can you get above it? | Yes | No - it emerges from under the ribs |
| Ballottable bimanually | Yes | No |
| Notch | No | Yes, on the medial border |
| Percussion note | Resonant - colon lies in front | Dull |
| Movement with respiration | Slight, downwards | Marked, downwards and medially |
| Direction of enlargement | Downwards | Towards the right iliac fossa |
The differences all follow from position. The kidney is retroperitoneal, so bowel lies in front of it (resonance) and it can be trapped between two hands (ballottement). The spleen is intraperitoneal and tucked under the diaphragm, so no hand can pass above it and it moves freely with respiration.