Yes, per the 2014 Senate Intelligence Committee report on the CIA's detention program: at least five detainees underwent rectal rehydration or feeding without medical necessity, often as a control tactic.
One documented case involved Majid Khan, whose pureed lunch tray (hummus, pasta, nuts, raisins) was rectally infused via tube. Similar procedures used Ensure or fluids on others like Khalid Sheikh Mohammed.
It was part of the post-9/11 enhanced interrogation efforts, not standard medicine.