All the following are criteria to diagnose postmolar GTN except
Plateau of serum b-hCG level (+- 10 percent) for four measurements during a period of 3 weeks or longer Rise of serum b-hCG level > 10 percent during three weekly consecutive measurements or longer, during a period of 2 weeks or more Serum b-hCG level remains detectable for 2 months or more Histological criteria for choriocarcinoma