Sources tell us that Sandra was feeling overheated and weak, and that fluid was building up in her chest. The big concern is blood clots, and doctors will likely be checking for infection.
The Food Network star's longtime partner, New York Gov. Andrew Cuomo, left a Billy Joel concert on Long Island to be by her side at the hospital. Doctors will monitor Lee for the next few days, but she is stable now.
In May, Lee underwent a double mastectomy after being diagnosed with breast cancer two months prior.
For the record: This post has been updated.