Pope Francis, the head of the Roman Catholic Church, underwent surgery hours after attending the annual Sunday Angelus prayer in St. Peter’s Square on July 4, according to the Vatican.

The pope had surgery for “colon diverticulitis,” according to Vatican spokesperson Matteo Bruni.

Diverticulitis is an inflammation that occurs when tiny sacs form in the colon’s lining. Diverticuli are pouches or sacs in the body. It’s normally asymptomatic, although it might cause discomfort and bleeding in some cases.

The Holy See press office said in a statement: “This afternoon his Holiness Pope Francis went to the Gemelli hospital — Rome — for a scheduled surgical intervention for a symptomatic stenotic diverticulitis. Surgery will be carried out by professor Sergio Alfieri. At the end of the surgery a medical bulletin will be issued.”