Former Senator Bob Dole of Kansas has checked himself into Walter Reed Army Medical Centre for what his spokeswoman described as a routine procedure.
Spokeswoman Marion Watkins said the 89-year-old Mr Dole is "doing very well" and is expected to leave the hospital soon.
Mr Dole's name drew mention as the Senate debated a UN treaty promoting equal rights for the disabled.
Mr Dole overcame disabling war wounds to forge a 36-year political career. In the early 1990s, he underwent successful surgery for prostate cancer and in 2001 he had surgery to treat an aneurysm.
Mr Dole spent 10 months at Walter Reed in 2010 after suffering pneumonia following knee surgery.
He was the Republican nominee for president in 1996, losing to Bill Clinton.