Untreated patients have increased risk for bleeding complications after surgery. Thus, if surgery is needed for any reason, treatment should be put in place to bring the hematocrit to a normal concentration before surgery.
Some patients have further disease progression despite treatment. After years of disease, several conditions may arise:
- Cells can undergo further changes and no longer overproduce red cells. For a time, the red cell count may stay near normal without treatment or drop below normal, resulting in anemia.
- The spleen may become further enlarged.
- Bone marrow may become fibrous or scarred, reducing its ability to make red cells and platelets, a condition called myelofibrosis, or more precisely, post-polycythemia vera myelofibrosis.
- The platelet count may fall to low levels.
- Immature white cells may be released from the marrow into the blood.
PV can also transform into other blood cancers such as acute leukemia or myelodysplastic syndromes, but this is a very uncommon occurrence.