Coach Joel Quenneville said he learned of Crawford's illness Saturday morning.
"His procedure went pretty well today," Quenneville said after a 3-1 loss to the Philadelphia Flyers. "… Thanks to our medical staff and the Flyers medical staff today. They did a great job of helping us out."
Quenneville said he didn't know if Crawford would have to remain in the hospital overnight and said he was unsure if Crawford's appendix burst.
"I don't know the details. I don't think so," he said. "I think it was clean and went as best as it could."
Crawford is 12-6-2 with a 2.27 goals-against average and .927 save percentage in 20 games this season.
"He's the best goalie in the League; him and Carey Price, you can put them in a category by themselves," said Scott Darling, who started in Crawford's place and made 27 saves. "He brings it every night. He's been great all year. And he's just a great guy. Just one of the boys. We missed him in the room today for sure."
If Crawford is out for two weeks, he would miss seven games, potentially returning Dec. 18 against the San Jose Sharks. Three weeks would mean he'd be out for 10 games, with a return date of Dec. 27 against the Winnipeg Jets.
Darling likely will receive the bulk of the starts during Crawford's absence. In eight games, Darling is 4-1-1 with a 2.81 GAA and .907 save percentage.
"For me, it stinks, because he's a good friend and I want him to be well, play and help the team," Darling said. "But it's exciting for me to get a chance to play a couple games."
Quenneville said he has faith in Darling, who will start against the Jets at United Center on Sunday (7 p.m. ET; SN, CSN-CH, NHL.TV).
"He's played in some big games and some back-to-backs as well, and it's a good opportunity for him as well to take advantage of the net and get a lot of games in not a lot of time," Quenneville said. "It will be a real good test for him."
Goalie Eric Semborski was signed to an amateur tryout Saturday to be Darling's backup. Rockford, the Blackhawks' American Hockey League team, was preparing for a game in Grand Rapids, Michigan, so there was no chance of getting a goalie from there.
Chicago also had to pick a goaltender with no professional experience because of its NHL salary cap situation. Semborski, 23, was a goaltender on the Temple University club hockey team who works as coach and instructor with the Ed Snider Youth Hockey Foundation.
"We knew we're pressed against the cap, so we had our hockey ops looking for a goalie that's not a professional and doesn't have any money tied to them so they wouldn't be counted [against] the cap, so that was a factor," Quenneville said. "That's why [goalie coach] Jimmy [Waite] didn't get a chance to play today."
