Cubs pitcher Kerry Wood will be out at least four weeks after an exam revealed a partial tear in his right rotator cuff.

Wood underwent an arthrogram at Northwest Memorial Hospital Friday. The team said Saturday the options are conservative treatment or possible arthroscopic surgery on Wood's shoulder. A final decision has not been made yet on treatment.

Wood had undergone an MRI on June 26 in Cincinnati, but that did not include an arthrogram, which is more detailed and provides more information, the Cubs said.

Wood, 29, underwent arthroscopic surgery on his right shoulder last Aug. 31.

Wood began the season on the disabled list. After being activated, he went 1-2 with a 4.12 ERA in four starts before going back on the injured list June 7. He was on the DL three times last season, the final time on Aug. 30, one day before his surgery.

Wood had a huge year as a rookie in 1998 as he had a 20-strikeout game in his fifth major league start and won the National League Rookie of the Year Award.