Bonderman, Detroit's No. 2 pitcher, experienced a clot in the axillary vein, located near the clavicle in the front of the shoulder, which is the vein responsible for returning blood from the arm to the heart. The clot was due to thoratic outlet compression syndrome.
"Think of [the vein] like a straw, and it was pinched," team athletic trainer Kevin Rand said. "That's what thoratic syndrome does."
The 25-year-old right-hander stayed over Friday night at Detroit Medical Center after undergoing a thrombosis, a procedure that dissolves the clot. Then he underwent an angioplasty Saturday morning to make sure the vein was clean.
Bonderman was released Saturday morning from the DMC. He arrived at the Tigers' clubhouse around the seventh inning of his team's 8-4 win over Cleveland. His right arm appeared swollen from the surgeries.
"I'm done for a while -- I know that," Bonderman said. "We'll wait and see. I'll go to the doctors and go from there.
"It's something I know I can come back from. It's not like you're rebuilding something; you're trying to make it better. I look at it as an opportunity to get it right, and when I come back, I'll be healthy and I'll have a fresh arm."
The rest of Bonderman's season is in question. Doctors now will try to find the cause of the clot, whether the first rib on his right side was responsible. And if the rib is the cause, it's unknown whether doctors will have to remove the rib. Examinations the next few days should reveal the cause.
Rand said making any predictions about Bonderman the rest of this season would "just be speculation," because of the extensive examinations still required. But if surgery becomes necessary, Bonderman's immediately future could become cut and dried.
"If surgery is, in fact, indicated," Rand said, "he will probably be lost for the season."
Tigers pitcher Kenny Rogers suffered a similar clot in 2001. He had season-ending surgery that year to remove a rib.
The loss of Bonderman would add further turbulence to this puzzling Tigers season. Prior to his injury, Bonderman had proven one of Detroit's best starters, tossing quality starts in his last four games.
"Times like this, you find out a lot about your team and how tough you are," manager Jim Leyland said. "We've been through a lot of tough stuff, one thing after the other. We feel bad for Jeremy Bonderman, obviously, but it's in the proper hands and it'll get taken care of. That's all I'll say about that."
Leyland said right-hander Armando Galarraga will pitch Sunday in Bonderman's spot in the rotation. In his second start since returning from a hyperextended knee, left-hander Dontrelle Willis will start Monday's series finale with the Indians.
The Tigers will not immediately fill Bonderman's roster spot, but plan on bringing reliever Aquilino Lopez off the bereavement list Monday.
Before Saturday's game, some players seemed shocked by the news. They tried to put the loss into perspective when asked by reporters.
"It's huge," third baseman Brandon Inge said. "He's got a huge heart. He doesn't go out there and worry about things like wins or strikeouts. He's a bulldog and he goes out there and gives it his all and tries to give us a chance to win. That's why you respect him and want to give him the ball."
Bonderman's best friend on the team, starter Justin Verlander, acknowledged the impact of the injury on the team, but he was just happy Bonderman made it through both procedures without further problems.
"As a friend, you worry about him. [A blood clot] is dangerous, and I'm glad he came out OK," Verlander said. "But it's also a big blow to the team, and I'm not going to pretend like it isn't."
Another friend and teammate, pitcher Nate Robertson, said Bonderman had complained the last few days that his arm felt "different," "weird" and "heavy."
"It's such a weird deal," Robertson said. "He's just 25 years old, and you wouldn't think he would have to go through something like this. You just got to think, no matter what, that some way, somehow, he'll get back with us."
Closer Todd Jones tried his best to put a positive spin on the news amid the sad faces.
"One more chapter in the greatest comeback in baseball history," he said. "The guys in here, we can overcome it."
Scott McNeish is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.