Cardinal Kikuchi Tarcisio Isao of Tokyo wrote on social media that he’d had an audience with Pope Leo on Monday, and said the pontiff felt “nothing wrong” physically.

He said the Pope had decided to check in for surgery as soon as possible because he was due to travel to Latin America in early November, and was keen to stick to that plan.

The trip is particularly significant because it includes a visit to Peru, where the pontiff was a missionary and then a Bishop for many years.

Despite all the reassurances, the news has shaken Catholics all over the world.

“Am I worried? Yes, because I certainly wasn’t expecting anything like this,” Vatican Secretary of State Cardinal Parolin told journalists on Tuesday.

He agreed that the news was like a “bolt from the blue”, but said the cardinals had been struck by the Pope’s “serenity” and were confident in his recovery.

Outside Gemelli Hospital, which has treated several popes and is home to a large statue of John Paul II, a few Catholics lingered after the pontiff was admitted.

Carla had come specially, wanting to be close.

“He seems calm, so we are calm too – even though illness is always unpleasant,” she told the BBC. “We will wait here and pray.”

“I was in St Peter’s Square when he made the announcement, and I felt really awful,” said Elsa, who was also present. “I was really taken aback,” she said, explaining that when Pope Leo was elected she had thought he was a younger, healthier pontiff.

“It turns out he’s vulnerable too. I really hope it’s something superficial, that can be contained, like he told us.”