Comparison of specific X-ray imaging signs between the perforation and non-perforation groups, n (%)
| Variable | Perforation group (n=113) | Non-perforation group (n=485) | χ2 | P value |
| Lucency over the liver shadow | 73 (64.60) | 0 | 130.635 | 0.000 |
| Falciform ligament sign | 51 (45.13) | 0 | 81.566 | 0.000 |
| Football sign | 42 (37.17) | 0 | 64.373 | 0.000 |
| Rigler sign | 35 (30.97) | 0 | 51.960 | 0.000 |
| Triangle sign | 18 (15.93) | 0 | 24.830 | 0.000 |
| More than any one of the above signs | 98 (86.73) | 0 | 202.775 | 0.000 |