"He was experiencing some discomfort during the trip to Detroit (last week)," Reich said. "Got scans done. It's a disk issue. That's a complicated issue. More meetings, more evaluations to come, more opinions to come. We want to do due diligence there."
Hilton spent several minutes on the ground in the team's Aug. 25 practice after he went up in double coverage on a deep ball. He later returned to practice. Hilton, like many of the Colts starters, did not play in the preseason finale against the Lions on Aug. 27.
"When you're talking about a guy like T.Y. Hilton, I mean him missing games -- all right that's an obvious big blow because he is not only a great player, but he's a great leader," Reich said. "... I had said several times to (general manager) Chris (Ballard), I really thought T.Y. was looking as good this training camp as I've seen him. He looked as fast as ever and as instinctive as ever. Even in the short time that he and (quarterback) Carson (Wentz) worked together, I could tell -- instant connection. I could feel that in talking to Carson. So that's unfortunate, but the good news is we've got good depth and guys will step up."
Hilton, 31, has been the Colts' No. 1 receiver throughout his nine seasons in Indianapolis, which include five 1,000-yard campaigns.
A free agent this past offseason, Hilton signed a one-year, $8 million contract to return to Indianapolis. He is guaranteed $8 million and can earn up to $10 million if he reaches incentives. He said he turned down a multiyear deal with the Baltimore Ravens to remain with the franchise. Hilton led the Colts in receiving yards with 762 last season and tied for the team lead with five touchdown catches.
The good news for the Colts is that Reich said Wentz and guard Quenton Nelson are at the stage in their returns from foot injuries where they can take part in full team drills. They did everything with the exception of team drills when they returned last week. A key for both of them will be how they respond to practices this week. The goal is for Wentz and Nelson to play in the Week 1 game against Seattle on Sept. 12.
"Part of the litmus test, with Quenton and Carson in particular, they need to be, as Chris and I talked about this, they need to be ready to go Wednesday," Reich said. "Like the game is being played on Wednesday so they can practice full on Wednesday, practice full on Thursday. So, in order to get there for Wednesday and Thursday, they're going to have to do some work this week. They're going to have to prove that they can bounce back from a good day's work and follow it up with another day. We'll see how this week goes."
The Colts' offense has been bitten by the injury bug this preseason.
In addition to Hilton, Tevi and Fisher, quarterback Sam Ehlinger is expected to miss five to six weeks with a sprained left knee, a source told ESPN's Adam Schefter.