D-backs right-hander Merrill Kelly had a procedure to dissolve a blood clot in his pitching shoulder Tuesday and is likely out for the remainder of the 2020 season, according to general manager Mike Hazen.

Kelly had been placed on the injured list after being scratched from his Monday start about an hour before first pitch with what the club said was a right shoulder nerve impingement.

Hazen said that the plan is for Kelly to take the next several days to a week to recover, and then head to Dallas to visit highly regarded vascular surgeon Gregory Pearl to be further evaluated.

“What caused the underlying issue needs to be answered,” Hazen said. “And that will happen with those next steps.”

The biggest question is whether there is a thoracic outlet issue like thoracic outlet syndrome, which, according to Johns Hopkins Medicine, is when nerves or blood vessels are compressed by the rib, collarbone or neck muscles at the top of the outlet.

Hazen emphasized that there has been no diagnosis of thoracic outlet syndrome at this point.

“I'm just telling you what we're investigating,” Hazen said. “I'm not saying what we're ultimately going to end up finding.”

Regardless, it seems like Kelly’s 2020 season has come to an end.

“I would not envision him coming back this year,” Hazen said. “It’s a tough loss for us.”

Kelly had been one of the team’s better starters this year, compiling a 178 ERA+ over his first five starts.

Madison Bumgarner could take Kelly’s spot in the rotation when it comes up Saturday. The left-hander, who is on the injured list with a mid back strain, threw a bullpen session Wednesday.

Relievers Taylor Clarke and Taylor Widener have both been starters throughout their pro careers and could step into the rotation as well.

Beyond that, the D-backs' depth has been tested this year.

Veteran right-hander Mike Leake elected not to play this year and prospects Jon Duplantier and Corbin Martin have both had injuries that make their availability for the rest of the season doubtful.