Final answer:
Medicare requires a prognosis of 6 months or less for certification of a terminal illness, but recognizes prognostic uncertainty. Terminal illness cannot be certified with an unknown or unspecified life expectancy for Medicare purposes.
Step-by-step explanation:
According to Medicare regulations, certification of a terminal illness does require a prognosis of 6 months or less if the illness runs its normal course. However, the regulations acknowledge that making medical prognoses of life expectancy is not always exact, and patients may still qualify for hospice care even if they live beyond this period. As a result, while life expectancy does need to be specified as limited, it is false to claim that a terminal illness can be certified with an unknown or unspecified life expectancy for the purpose of Medicare eligibility.