The Mirror reports that Hammond was suffering from stomach pains but told doctors to delay his operation so he could have lunch with competition winners.
A friend of the motoring presenter said: "Three people had won lunch with Richard. One was supposed to be on holiday but had given it up because he was going to meet his hero.
"Richard knew this so didn't want to disappoint him. But he couldn't eat anything because the operation was just a few hours after. He only drank a glass of orange juice.
"After the meal they said their goodbyes and Richard checked into hospital."
Though the operation went without a hitch, doctors discovered the 38-year-old had kidney stones and a hernia. Hammond will have the stones removed next week.
After the appendix surgery, Hammond said: "I started getting pain on Monday night and I went to the doctor's first thing the next morning. I was referred to a consultant and he said it was appendicitis and I'd have to have it out that day. The pain wasn't too bad and having your appendix out now is like having a tooth out."