Doctors in China performed a surgery on a two-year-old boy to remove a parasitic twin inside his belly.

The baby, Xiao Feng, was taken to a hospital in Huaxi after he suffered from heavy breathing problems due to his enlarged stomach. The baby's tummy swelled to two thirds of its normal size. The doctors conducted MRI scans and X-rays to find a developing fetus measuring 20 cm inside the baby's stomach.

The medics conducted an emergency surgery on Xiao and removed his 'twin brother'.

According to Mirror, Xiao absorbed the fetus in his mother's womb. The fetus had developed a full spine, fingers and toes. Such cases of conjoined twins are known as cryptodidymus and are rare. It happens when fertilized eggs do not separate completely.

Sometimes a parasitic twin survives but not when the fetus is absorbed into another twin. These twins are different to conjoined ones, here one fetus is underdeveloped and is parasitic. The independent twin is called the autosite.

Doctors say that it is easier to remove parasitic twins than to split conjoined twins as their organs are separate.

This is not the first case where a parasitic twin was removed from a baby. In 2012, a three-year-old boy in Peru underwent surgery to remove a nine inch-long parasitic twin weighing a pound and a half.

A year before that Greek doctors removed a two-inch embryo from a nine-year-old girl.