Prince Philip, the husband of Queen Elizabeth II, has been admitted to the hospital for a planned exploratory operation following abdominal abnormalities discovered in the past week, Buckingham Palace announced Thursday.
The prince, 91, is expected to remain in the hospital for two weeks, according to the Palace. This is a planned operation and was not an emergency, a spokesperson for Buckingham Palace told NBC News. The surgery is a result of medical investigations during the past week.
The announcement comes three days after Philip pulled out from a gala reception attended by the queen at St. James Palace after falling ill. The two illnesses are unrelated, a Buckingham Palace spokesperson told the BBC, adding that Monday's absence was related to his losing his voice.
Philip was at a garden party with the queen at Buckingham Palace on Thursday afternoon and showed no signs of sickness, according to the BBC. He was reportedly driven to the hospital after the party and walked in under his own power.
This is the Duke of Edinburgh’s fourth trip to the hospital in 18 months, as he was treated for a recurring bladder infection in August of last year. In December of 2011, he underwent heart surgery to have a stent put in.
Philip is the oldest spouse of a reigning British monarch in history. He married Queen Elizabeth in November of 1947, upon which he was granted the title of the Duke of Edinburgh. He was bestowed the title Lord High Admiral on his 90th birthday last year by his wife.
Prince Philip and Queen Elizabeth have four children together: Prince Charles, Princess Anne, Andrew, the Duke of York, and Edward, the Earl of Wessex.
Philip, whose other titles include Earl of Merioneth and Baron Greenwich, is the only son of the late Prince Andrew of Greece and comes from a family of Danish descent. Philip became a naturalized British subject in 1947 and took the family name of Mountbatten upon his marriage to the queen. His maternal grandfather, Prince Louis of Battenberg, married one of Queen Victoria's granddaughters, meaning Queen Victoria is the great-great-grandmother of both Philip and Elizabeth.