Lord Tim Bell, the leading PR and advertising figure who was a close adviser to Baroness Thatcher, said she was expected to need several days of recuperation. It could mean she will spend Christmas in hospital, where she has been accompanied by her daughter Carol.
Lord Bell said the former politician had been in some pain earlier in the week and was sent by her doctor to hospital where it was decided the operation was required.
It was a short procedure using what was described as "minimally invasive surgery", he said."She's fine," he added.
More top news
Jessica Ennis Hill's coach has revealed that he will not be encouraging the heptathlon champion to defend her title in the Rio Olympics.
Massimo Cellino has said he introduced the club's 'pie tax' to punish supporters who criticised him - but he insists he was only joking.
Justin Fashanu's neice says the culture surrounding modern football makes it almost impossible for gay players to come out.