Version July 2025
| Descriptor | Definition |
| Time course | |
| Recent | PVT presumed to be present for <6 months |
| Chronic | PVT present or persistent for >6 months |
| Percent occlusion of main PV | |
| Completely occlusive | No persistent lumen |
| Partially occlusive | Clot obstructing >50% of original vessel lumen |
| Minimally occlusive | Clot obstructing <50% of original vessel lumen |
| Cavernous transformation | Gross portoportal collaterals without original PV seen |
| Response to treatment or interval change | |
| Progressive | Thrombus increases in size or progresses to more complete occlusion |
| Stable | No appreciable change in size or occlusion |
| Regressive | Thrombus decreases in size or degree of occlusion |
