New York ? Former President Bill Clinton will return to the operating table Thursday to remove fluid and scar tissue from the left side of his chest — a rare but treatable side effect of his quadruple-bypass surgery six months ago.

“It’ll knock me out of commission for a week or two, and then I’ll be back to normal,” Clinton said in one of two Washington appearances Tuesday.

Doctors said the fluid is pressing on his lower left lung, giving him three-quarters of his normal lung capacity, but poses no immediate health risk.

“This is a relatively low-risk procedure and we expect full functional recovery in a limited amount of time,” said Dr. Joshua Sonett, who will perform the surgery at Columbia Presbyterian Medical Center.

Clinton looked healthy Tuesday, as he and former President George Bush shuttled around Washington.

“I’m doing great,” Clinton told the New York Daily News before their White House appearance.

“You should have seen him going, town to town, country to country, Energizer Bunny here. It killed me,” Bush said.

Clinton and the elder Bush are keeping a date Wednesday to play golf with Greg Norman to raise money for tsunami aid. Then he’ll head to New York, where he’ll meet his wife, Sen. Hillary Clinton, before the surgery.

During the one- to three-hour surgery, Sonett will thread a tiny video camera inside Clinton’s left chest. Depending how much scar tissue he finds, he may need to make another cut in Clinton’s chest to bring in small surgical tools.

Clinton is expected to stay in Columbia Presbyterian for three to 10 days, until he is strong enough to walk out by himself.