First Lady Melania Trump had surgery on Monday morning for what aides called a "benign" kidney condition.
Trump's communications director, Stephanie Grisham, said the first lady had an embolization procedure, which starves the blood supply to the affected area.
She said, however, the first lady would likely remain at Walter Reed for "the duration of the week" to recover.
President Donald Trump traveled via Marine One later in the evening to visit his wife. Doctors do that with an embolization, meaning a catheter is snaked into the blood vessels of the kidney to find the right one and block it.
Such tumors are usually found by accident, when doctors are taking images for another reason, he said.
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The White House withheld additional information about the first lady's condition, citing her right to privacy. They have a 12-year-old son, Barron.
Trump joked at lunch that support for the first lady was so high that he had her promise she wouldn't run against him, said a person familiar with the discussion but not authorised to discuss a private conversation. She will leave the hospital in 2 or 3 days.
The Trumps and their marriage have been under scrutiny in recent months after revelations that a porn actress was paid $130,000 in hush money to keep quiet about claims she had sex with Trump in 2006. Trump also denies the allegations from Karen McDougal.
Mrs. Trump unveiled her official policy platform "Be Best" last week.
On Monday, the White House released a statement informing the operation to be successful.
Republished with permission from the Associated Press.