Peter Diana, Post-Gazette photos Pirates pitcher Kip Wells stretches prior to a workout earlier this month. Click photo for larger image. More Coverage: Pirates Notebook: Bullington makes big step in recovery from surgery Pirates Photo Journal Smizik: McClendon critics way off base

BRADENTON, Fla. -- Kip Wells has a blood clot near his right arm, and it could lead to surgery that keeps him out of the Pirates' lineup all season.

General manager Dave Littlefield yesterday announced Wells has "100 percent blockage" of the axillary-subclavian vein, the primary blood vessel from the chest to the arms and neck. The clot typically is treated first with anticoagulants and, to prevent recurrence, surgery that removes any bone compressing the vein.

It was not immediately known if Wells has any bone compressing the vein, but that is highly common in such situations. If he does and elects to have surgery, precedent shows he will need five to eight months to fully recover.

Wells was diagnosed Saturday in St. Louis by Dr. Robert Thompson, a vascular surgeon and noted blood-clot specialist at Washington University. Thompson performed an angiogram, an examination in which scanning dye is inserted into the patient through a catheter in the groin.

Wells did not return to the Pirates in time for their morning workout yesterday. He was still in St. Louis, Littlefield said, pondering whether to seek a second opinion, examine other options or proceed with treatment by Thompson. That decision is expected today or tomorrow. If Wells opts for surgery, that would come later in the week.

Littlefield described Wells as down in a phone conversation they had late Saturday night.

"Just going through the procedure, he was quite tired, a little drugged up, concerned, disappointed," Littlefield said. "Players work hard in the offseason and don't want to have setbacks. Just to go through this and knowing it's going to set him back a little bit, he was disappointed. But I think he's anxious, too, to get it resolved."

Thompson has operated on two Major League Baseball players: Colorado Rockies pitcher Aaron Cook in 2004 and Arizona Diamondbacks outfielder Luis Terrero the previous year.

In each case, the patient was diagnosed with thoracic outlet syndrome, a blood clot in the same area, which Thompson addressed by removing the top rib on the right side and redirecting a vein to the wrist. Cook returned to baseball in eight months and went 7-2 down the stretch for the Rockies last season. Terrero was back in five months.

But that might not be Wells' condition.

"Nothing has come up in regards to that term," Littlefield said of thoracic outlet syndrome.

The likeliest match for Wells' symptoms is a condition called effort thrombosis. It occurs when an arm is used in repeated and stressful fashion.

"The action of throwing has been identified as what had caused the blockage." Littlefield said.

Wells led the Pirates with 182 innings pitched last season and missed only one start because of a cracked fingernail and blister. He also made all his scheduled mound appearances in minicamp last month and the early part of spring training.

It was not until recently, Littlefield said, that Wells began complaining of arm fatigue.

"He hadn't bounced back like he had in the past," Littlefield said. "It became something that stayed with him."

Wells' most recent pitching session was an extended one Wednesday that was his third of spring training. The next day, he informed the Pirates his arm felt tired.

Although such fatigue is seen frequently in spring training, the team's doctors on site -- usually based at Allegheny General Hospital -- checked Wells' pulse and found it was markedly different in each arm. They determined Wells should see Thompson, and he was flown to St. Louis Friday night.

In the cases of Cook and Terrero, they needed to be rushed for emergency procedures that might have saved their lives. Wells' situation never became that dire, Littlefield said.

"It definitely can be a serious matter," Littlefield said. "There's always a concern in regards to clots, aneurysms, things like that. Evidently, we moved on it very quickly. ... I really compliment our doctors from the standpoint of detecting this."

Wells, 28, was expected to be an anchor of the Pirates' rotation despite having gone 8-18 with a 5.09 earned run average last season. His loss would leave the team with Oliver Perez, Zach Duke and Paul Maholm as the only certain starters. Others vying for starting duty are Victor Santos, Ryan Vogelsong, Ian Snell and, if health allows, Sean Burnett.

Littlefield did not wish to discuss contingency plans if Wells is not available for any significant span.

"I don't think we're at that point," he said. "We'll have to wait and see what the second opinion is, if that's where he goes, and then we'll prepare for it once we get that information. We're always looking at the what-if scenarios that take place at any position, so you're always prepared for those things."