A blood clot discovered near his right arm may force Pirate pitcher Kip Wells to miss the 2006 season.

BRADENTON, Fla. — Pittsburgh Pirates pitcher Kip Wells is suffering from a blood clot close to his right arm, an injury that could jeopardize his season.

General manager Dave Littlefield described the clot as a "100 percent blockage" of the axillary artery under the clavicle, the primary vessel that carries blood from the chest to the arms.

Wells, 28, told the team he still must determine if he wants to get a second opinion before having surgery, a decision he is expected to make within two days. If Wells has surgery, he would likely miss five to eight months of playing time.

Wells' condition was first detected late last week at spring training and formally diagnosed Saturday in St. Louis by Dr. Robert Thompson, a vascular surgeon at Washington University. Thompson conducted an angiogram, a procedure that involves the insertion of a catheter in the groin, to confirm his initial tests.

Littlefield said Wells' case never reached an emergency level, as some blood clots do. But he added that the team acted swiftly once its doctors noticed Wells had dramatically different pulse readings in each arm.

"There's always a concern in regard to aneurysms, clots and things like that," Littlefield said. "But we moved on it very, very quickly."

Wells pitched a staff-high 182 innings last season and showed no signs of the ailment until this spring, Littlefield said. Wells complained of arm fatigue early in spring training, but didn't miss any of his three scheduled pitching sessions.

"Players work hard in the offseason and don't want to have setbacks," Littlefield said. "But I think he's anxious, too, to get it resolved."

The Pirates were expecting Wells to be one of the top two starters in their rotation. The right-hander is coming off a disappointing season — he was 8-18, the most losses in the majors, with a 5.08 earned run average. But he has performed far better in the past and had encouraging early results working with new pitching coach Jim Colborn.

Littlefield said he would wait until Wells' decision to begin considering possible roster moves to replace Wells.