Guymon said the endoscopy results had been a blow to the Harding family, which "had been hoping to get some better news.
"This means she is still in a very touch-and-go situation and she remains closely monitored by doctors. There's been no signs of improvement; this is still very much a life-threatening situation," Guymon said.
Meanwhile, South Jordan police remained tight-lipped about what they had learned about how the chemical a lye-based product known as Clean Force Fryer Cleaner got into the sweet tea mix. Early on, police had indicated the substance may have been confused with sugar by a Dickey's employee.
On Friday, however, SJPD spokesman Sam Winkler would not confirm if that still was investigators' working premise. All he would say was that he had nothing to release for now, though Winkler added, "We will have more information on Monday."
Guymon would not speculate on whether the investigation may have taken a more sinister turn, though he said he suspected the eventual police report may "contain some surprises." He would not elaborate.
Winkler had said earlier this week that in addition to talking with managers and employees, detectives would be reviewing the restaurant's video security camera footage for clues.
Harding was eating at the restaurant about 1 p.m. Sunday when she poured a glass of sweet tea from the self-service beverage bar. One sip later, her mouth and throat began burning, even after she attempted to spit out the tea.
Her husband rushed her to a nearby hospital, from where she was flown to the burn unit in Salt Lake City.
Though representing the family, Guymon said the Harding family had made no decision yet on whether to sue Dickey's.
The South Jordan restaurant's owner, John Thomson, has declined to discuss the incident other than to state that Harding is in his prayers, and that he and his staff are committed to fully cooperating with the investigation.