Prince Philip is progressing "satisfactorily" after undergoing exploratory abdominal surgery, Buckingham Palace announced Friday.
The palace said the operation took place Friday afternoon and that the results will now be analyzed.
"At this early stage, he is progressing satisfactorily," their brief statement read.
The prince entered hospital Thursday evening, much to the surprise of royal watchers who had not realized he was unwell enough to require surgery.
Buckingham Palace has not revealed what prompted the surgery, but says the prince is expected to remain in hospital for up to two weeks after surgery.
Queen Elizabeth has continued with her royal duties, and attended the Friday opening of new headquarters of the British Broadcasting Corporation's new Broadcasting House in central London. She had been scheduled to attend the event with her husband.
Prince Philip, who also goes by the title of Duke of Edinburgh, has been generally well in recent months, though lost his voice earlier this week, forcing him to miss some public events.
That may have come after he underwent non-invasive tests earlier in the week.
The news of the surgery came as a surprise to royal watchers, especially since he attended a garden party at Buckingham palace.
The 91-year old appeared relaxed, shaking hands and telling jokes, even though he would have known that he would be entering hospital later that day.
The palace says this wasn't an emergency admission and that the duke remains in good spirits.
Royal commentator Richard Fitzwilliams says it appears the palace is trying to respect the public’s right to know along with the prince’s desire not to cause undue alarm.
“Nobody wants to cause concern unnecessarily, because he’s a much-loved member of the family,” Fitzwilliams told CTV’s Canada AM Friday.
“…So it’s a question of balance. You don’t want to cause concern, but equally you want to keep your concerned public informed.”
While any kind of surgery at the prince’s age -- especially one involving general anesthetic -- cannot be taken lightly, Fitzwilliams notes that Philip is in remarkable health.
“There’s no question that he is somebody with an absolutely iron constitution,” he said. “One of the issues with the duke is it’s very difficult to get him to slow down. He’ll be a most impatient patient.“
Nevertheless, this is the fourth time Prince Philip has been in hospital in the last 19 months: he was admitted twice for a recurring bladder infection last year, and over Christmas 2011, he underwent treatment for a blocked coronary artery.
Fitzwilliams says the prince is likely eager to get back to his job, since he appears to thrive on activity. Indeed, he’s kept a busy schedule of late, including a trip to Toronto in April. He also joined the Queen last week for celebrations of the 60th anniversary of her coronation.
He will likely miss the events planned for his 92nd birthday next week, and since he likely will need to rest for several weeks after his surgery, he will have to bow out of several more.
The palace says while the Queen is concerned for her husband, she will go ahead with her scheduled engagements for the rest of the week.
And while the palace is also promising that there will be regular updates on the prince’s condition, they’ve asked the media to refrain from speculating on his condition.
