| Temporary risk factor | No | Yes | No | Yes |
| Laboratory risk factor | Yes | Yes | No | No |
| Women (n) | 9.0 | 55.0 | 6.0 | 39.0 |
| Recurrence (n) | 0.0 | 4.0 | 0.0 | 4.0 |
| Recurrence rate (%) | 0.0 | 7.3 | 0.0 | 10.3 |
| Temporary risk factor | No | Yes | No | Yes |
| Laboratory risk factor | Yes | Yes | No | No |
| Women (n) | 9.0 | 55.0 | 6.0 | 39.0 |
| Recurrence (n) | 0.0 | 4.0 | 0.0 | 4.0 |
| Recurrence rate (%) | 0.0 | 7.3 | 0.0 | 10.3 |
Temporary risk factors: OC use, pregnancy, surgery, trauma, immobilization.
Laboratory risk factors: antithrombin-, protein C– or S–deficiency, factor V:R506Q, G20210A prothrombin gene variation, hyperhomocystinemia, elevated factor VIII, lupus anticoagulant.