The results of the scan were normal, Dr. Ronny Jackson, Obama's physician, said.
"The president's symptoms are consistent with soft tissue inflammation related to acid reflux and will be treated accordingly," Jackson said in a written statement released by the White House.
Jackson recommended the scan after an ear, nose, and throat specialist from Ft. Belvoir Medical Center conducted a fiber-optic exam of the president's throat Saturday morning, under Jackson's supervision, "based on symptoms of a sore throat over the past couple weeks.
After that exam revealed swelling in Obama's throat, Jackson recommended "further evaluation with a routine CT scan," the doctor said.
"There's a lot in this story that didn't seem to hold true with what you'd normally see," ABC News Chief Medial and Health Editor Dr. Richard Besser said. "Normally for a sore throat, initially you'll do a test for strep. If it goes on for a couple of weeks, you might do a scope, but not a CT. It may be that he is a former smoker, he's the president of the United States -- you'll often see presidents get extra testing."
With nothing on Obama's schedule for the day, the presidential motorcade departed hastily just after 2 p.m., catching reporters off guard, for a rainy, 30-minute ride to the military hospital in Bethesda, Md.
It's unusual for a president to seek medical care outside the White House, but Press Secretary Josh Earnest insisted to reporters via email, during the president's visit to Walter Reed, that Obama's condition was not serious and that the president "has been complaining of a sore throat" and that Jackson had recommended some "diagnostic tests."
It was a quick visit: Obama's motorcade pulled out of the Walter Reed parking lot fewer than 30 minutes after it pulled in.
What treatment the president will receive depends on the severity of the symptoms and how long he has been experiencing them, Besser said.
"If this is the start of the symptoms for him, you would take a slow approach," Besser said. "You would have him raise the head of his bed, stop smoking, if he's still smoking, cut down on alcohol, and cut back on those foods that are causing problems. Only if those things don't work do you go with the medication."