A Colombian woman suffering from stomach pain was found to have a 40-year-old foetus inside her.

The 82-year-old, from Bogota, had what is known as 'lithopedion', or stone baby, when the unborn child develops outside the womb.

The woman was originally thought to be suffering from a stomach bug, NTD TV reports.

But scans revealed lithopedion, where the foetus becomes calcified.There are fewer than 300 cases reported in medical literature.

The woman will now will undergo surgery to have the foetus - mostly comprised of dead tissue - removed.

According to NTD, Dr Kemer Ramirez of Bogota's Tunjuelito Hospital said that the doctor overseeing the woman noticed something 'abnormal in her abdomen' - and suspected gallstones.

An ultrasound showed nothing then radiography of her abdomen revealed a tumour in her abdominal cavity.

Dr Ramirez explained: "This happens because the foetus does not develop in the uterus because it has moved to another place.

"In this case, the abdominal part of the woman is not a viable (place) and this is what happened, a calcified fetus because the body is generating defence mechanisms and it is calcified until it stays there encapsulated."

The patient is thought to have been transferred to another hospital to have the lithopedion removed.

In 2009, a 92-year-old Chinese woman was found to have a 60-year-old 'stone baby' inside her.

The first reported case of lithopedion was Madame Colombe Chatri, a 68-year-old French woman.

An autopsy after her death in 1582 revealed she had been carrying a fully-developed stone baby in her abdominal cavity for 28 years.

- Daily Mail