Presence of kidneys, spleen, liver, and ribs in ATP approach.
| Disc Level | Right Side | Left Side | ||||
| Kidney | Liver | Rib | Kidney | Spleen | Rib | |
| Percentage of Time the Kidneys, Spleen, Liver, and Ribs Are Present in ATP Approach | ||||||
| L1 to L2 | 37% | 56% | 33% | 44% | 22% | 41% |
| L2 to L3 | 43% | 30% | 10% | 26% | 10% | 11% |
| L3 to L4 | 11% | 9% | 0% | 5% | 3% | 0% |
| L4 to L5 | 0% | 0% | 0% | 0% | 0% | 0% |
| L5 to S1 | 0% | 0% | 0% | 0% | 0% | 0% |
| Percentage of Obstruction Caused by Kidneys, Spleen, Liver, and Ribs When Present in ATP Approach | ||||||
| L1 to L2 | 67.9% | 92.5% | 30.1% | 42% | 54% | 37% |
| L2 to L3 | 66.3% | 92.2% | 20.0% | 44.9% | 50.0% | 26.6% |
| L3 to L4 | 78.9% | 100% | NA | 53.9% | 57.1% | NA |
| L4 to L5 | NA | NA | NA | NA | NA | NA |
| L5 to S1 | NA | NA | NA | NA | NA | NA |
Abbreviations: ATP, anterior-to-psoas; NA, not applicable.