Gee, 26, is 6-7 with a 4.10 ERA in 17 starts, and he was scheduled to open the team's second half Friday in Atlanta. Instead, the Mets will shuffle their rotation, with Chris Young pitching Friday and Miguel Batista joining the rotation either Wednesday in Washington or Saturday at Citi Field -- though the exact dates and order could change if Johan Santana's sore right ankle is not fully healed by the weekend.
A second source said that the team will call up a left-handed reliever -- either Josh Edgin or Robert Carson -- to replace Gee on the roster.
But of far greater concern to the Mets was the status of Gee, who first brought his discomfort to the attention of trainer Ray Ramirez following Saturday's start. Fellow pitcher R.A. Dickey said Gee came to him in the dugout that day and asked for Dickey to feel his hand, which was cold. Dickey recommended that Gee visit Ramirez, who sent him to the hospital for an MRI.
"I'm really nervous for him," manager Terry Collins said. "I'm really scared for him. I just know, in the past, guys -- their careers could be over if their arm doesn't respond to the treatment."
General manager Sandy Alderson did not immediately return a telephone message, and Gee, who is resting in New York, did not respond to a text.
"My concern is obviously what the rehabilitation time is going to be," Collins said. "Is he going to miss a month? Is he going to miss two months? Is he going to miss the rest of the season?"
Gee has endured no major medical issues since tearing the labrum in his right shoulder in 2009 and ultimately avoiding surgery. But Parnell, who missed 35 games last April with a blood clot in his pitching hand, said doctors were never able to explain the cause of his own less-serious injury.
Parnell was able to dissolve his clot in time through an aspirin regimen. But the invasiveness of the angiogram procedure, which requires doctors to access the body through the femoral artery in the thigh, can stall recovery for weeks.
"The worst part is the angiogram going through the leg," Parnell said. "Since mine was such a small scale, the healing process was through the catheter through the femoral artery. I could have pitched the next day if it wasn't for the angiogram. But I'm sure with his being on a greater scale, I don't know all of what that entails."
For now, it involves waiting and seeing. Collins decided to proceed with Batista in the rotation in the short term because, in his words, "We've got to find out what we have." But if Gee misses an extended period of time, the Mets will consider calling up top prospect Matt Harvey, who is 2-0 with a 1.88 ERA, 28 strikeouts and seven walks over his last four starts for Triple-A Buffalo.
That move will not happen immediately because Collins wants, in his words, wants "to make sure he's ready." Said the manager: "I don't want to put him in a situation where he can fail."
But far more than roster machinations, the Mets are concerned with Gee's health. Parnell, who is keeping up to date on Gee's condition through his wife, Kari Ann, said that his own clot last April "was on a very, very, very small scale compared with what [Gee] is going through."
"It's something that just kind of sneaks up on you," Parnell said. "There's really no warning signs or anything like that. It's scary. You really don't know."
Third baseman David Wright offered a similar perspective after reaching Gee on the phone from his hospital bed Monday night.
"Right now, we're not so much worried about when he's going to come back," Wright said. "His health is a lot more important than our starting rotation."