Julianna Margulies may be leaving “ER” without George Clooney on her arm. “I don’t know that it’s necessarily smart for me to come back for one scene and scoop Julianna up and walk out,” Clooney told a meeting of the Television Critics Association in Pasadena, Calif., when asked if he might appear once more on the top-rated NBC medical drama. Clooney, who played Dr. Doug Ross, left “ER” last February. Margulies, who plays nurse Carol Hathaway, is due to leave at the end of this season. Their characters broke up on the show, though she became pregnant and produced twins — leading to speculation that viewers might see them reunited in a final episode. There were even rumors, which Clooney dismissed as untrue, that he was being offered $2 million to reappear. “No one’s talked to me about that,” Clooney said. Meanwhile, Kellie Martin (she plays the eager Lucy Knight) broke the news Thursday that she is exiting “ER” at the end of the season.