International travel medical plans are designed to provide medical cover for people traveling outside their home country and can be purchased for family members visiting you in the US.  These plans cover unforeseen illness, accident and injuries but typically do not cover pre-existing medical conditions.

Related articles:

• Will international medical insurance cover pregnancy and childbirth?
• Does the pre-existing condition exclusion only apply to family members traveling with me?
• Are Family Members covered?
• My parents are visiting in the US for 3 months. If we purchase international medical insurance for them, are we required to insure them for the entire stay?
• What is "International Medical" travel insurance?