US First Lady Melania Trump had surgery Monday for what aides called a "benign" kidney condition, and will remain in hospital for the rest of the week.
The Slovenia-born wife of Donald Trump underwent an embolization procedure, said her communications director Stephanie Grisham.
"The procedure was successful and there were no complications," Grisham said.
But the 48-year-old former model is expected to stay in hospital "for the duration of the week."
"The first lady looks forward to a full recovery so she can continue her work on behalf of children everywhere," the spokeswoman added.
Hours after the procedure, President Donald Trump departed the White House for Walter Reed National Military Medical Center, where the first lady is being held just north of Washington.
The hospital facility has treated many presidents and first families.
Jeffrey Leef, associate professor of radiology at the University of Chicago, told AFP that embolization is most frequently used to isolate a tumour.
The procedure "introduces a small catheter into the arterial system of the body" with the aim of obstructing the blood vessel, Leef said.
According to Elizabeth Kavaler, a urologist at Lenox Hill Hospital in New York, the first lady may have a common, benign tumour of the kidney called an angiomyolipoma, or AML.
"They are more common in women. They can grow but they are not cancerous," Kavaler said.
Leef said that "one of the ways it can manifest itself is with a little bit of blood in the urine, or maybe pain."
He added that it is common to stay overnight after the procedure.
"The most common side effect is pain," Leef said.
"Often, you need temporarily a type of pain control that can only be provided within a hospital."