US Vice-President Kamala Harris became the first woman to - briefly - be given presidential powers while Joe Biden underwent a regular health check.
Ms Harris, 57, was in control for 85 minutes, while Mr Biden was placed under anaesthesia for a routine colonoscopy on Friday.
Mr Biden's doctor released a statement after the operation, saying he was healthy and able to execute his duties.
The medical examination came on the eve of the president's 79th birthday.
Ms Harris carried out her duties from her office in the West Wing of the White House, officials said.
She is the first woman - and the first black and South Asian American - to be elected US vice-president.
White House Press Secretary Jen Psaki said the temporary transfer of powers in such circumstances was not unprecedented, and that it was part of the process set out in the US constitution.
"As was the case when President George W Bush had the same procedure in 2002 and 2007," she said in a statement.
The president was seen smiling as he returned to the White House. "I feel great," he said.
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