There was no indication anything was wrong with Princess Kate, 42, before she was admitted to hospital on January 16.
Sources claim that the news came as a surprise to family friends and people who work closely with the royal family.
He writes New York Post.
The princess was last seen in public on December 25 when she and her husband, Prince William, took their three children to Christmas Mass.
Watch the video: Praise for the princess after this
Middleton is also said to have looked in good shape until January 9 when she celebrated her birthday privately with her family at Adelaide Cottage in Windsor, England.
Just one week later, the palace announced to the world that the future queen had undergone successful surgery.
The court announced on January 17 that the Princess of Wales had undergone planned abdominal surgery, but did not go into further detail about the type of intervention involved.
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– The Princess understands the interest that this statement will arouse. She hopes the public understands her desire to have as much normal time as possible for the children, and wants her personal health information to remain private, the court wrote in a statement.
Kensington Palace also indicated that the princess is unlikely to return to public duties until after Easter.
More visits to the hospital
She is not the only member of the British royal family to visit the hospital this month.
Two hours after the news about the princess, Buckingham Palace announced that Britain's King Charles would undergo treatment for an enlarged prostate.
– His Majesty's condition is benign and he will be admitted to the hospital next week for a corrective operation. She added that the King's public engagements will be postponed for a short period to restore dignity.
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