"More precautionary stuff with our team doctor," coach Brett Brown said of Carter-Williams' hospital stay. "It's a right-knee infection that really is being monitored closely, but nothing to get too overly concerned with."
Carter-Williams was injured while bumping knees with a Detroit Piston on Dec. 1 at the Palace of Auburn Hills. He remained in that game and played Tuesday against the Orlando Magic at the Wells Fargo Center.
The 22-year-old finished with 27 points, 12 rebounds, and 10 assists in the 126-125 double-overtime victory against the Magic.
"When you looked at it during the overtime, you realize that there was something going on a little bit more than a sore knee," Brown said. "But at this stage, he's in good hands. In relation to how long that's going to take place, I don't know."
The 11th overall pick out of Syracuse did not practice Thursday. He went to the hospital later that day while his teammates flew to Charlotte for Friday's game against the Bobcats.
Carter-Williams was named NBA Eastern Conference rookie of the month on Tuesday.
He led all rookies in scoring (17.2 points per game), assists (7.3), steals (2.9), and minutes (36.2) over 13 games he played in October and November.
Carter-Williams missed four other games with a bruise to the arch of his left foot.
The Sixers host the Los Angeles Clippers on Monday before a two-game road trip to the Minnesota Timberwolves (Wednesday) and Toronto Raptors (Friday). They will host the Portland Trail Blazers on Saturday.
Brown said he wasn't sure whether Carter-Williams would make the road trip.
"I just keep getting, again, day-to-day advice from people that know a lot more than I do," the coach said. "There's no timeline."