Baby born in Hong Kong with what may have been ‘absorbed’ siblings inside her

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A baby girl was born at Hong Kong’s Queen Elizabeth Hospital in 2010 with partially formed fetuses between her liver and left kidney, in a case that was recently chronicled in the Hong Kong Medical Journal and remains Hong Kong’s first documented case of a rare condition called fetus in fetu.

At first, doctors thought that the baby girl had tumors in her abdomen. Upon closer inspection they realized the structures were actually two partially developed fetuses. One fetus weighed 14.2 grams while the other was approximately 9.3 grams. Both appeared to be eight to 10 weeks into gestation and had already developed skin tissue, bone with bone marrow, a primitive brain, ribs, intestines as well as limbs.

What caused the abnormality is still unclear, although there are a couple of theories. One theory is that fetus in fetu is an elevated form of teratoma, a tumor that gives rise to cells that can form mature, recognizable structures including skin, hair and bone. Another theory is that during embryonic development, a blastocyst that developed from a single fertilized egg collapsed. Its inner cells containing genetic material divided into three separate embryos within a shared placenta. This is a common occurrence during multiple embryonic development and results in multiple babies. However, in this case, during fetal development the baby girl’s fetus ended up wrapping itself around the other two fetuses. With no functional organs, the two other fetuses relied on the baby girl’s blood supply to sustain themselves.

Doctors removed the parasitic fetuses from the girl’s abdomen while she was three weeks old, and she has since fully recovered. While there are only 200 documented cases worldwide, fetus in fetu is thought to occur in one in 500,000 births worldwide.

1. Normal triplet embryonic development
2. Normally developing fetus absorbs two partially developed fetuses
3. Normally developing fetus continues to grow
4. Location of partially developed fetuses in girl’s lower abdomen
5. The two structures have limbs, a brain, skin and umbilical cord
6. The two structures display parasitic behavior, taking blood from the baby girl

VOICEOVER (in English):

“A baby girl was born in Hong Kong in 2010 with a growth in her left side that turned out to be two partially formed fetuses between her liver and left kidney.”

“The girl’s condition is known as fetus in fetu, which occurs when a partially developed fetus is absorbed into a normally developing fetus.”

“The abnormality may have first started as normal triplet development when cells in the blastocyst split to form three embryos.”

“As the embryos developed into fetuses, two of them were enveloped by the third fetus.”

“The third fetus continued to grow, while the other two fetuses stopped developing after reaching eight to 10 weeks old.”

“The two other fetuses, one weighing 14.2 grams and the other 9.3 grams, were found lodged in the baby girl’s lower abdomen between her liver and left kidney.”

“They had developed arms and legs, along with primitive brain matter, intestines, skin and umbilical cords.”

“Since the two fetuses had no functioning organs, they used the baby girl’s blood supply to sustain themselves.”

“Fetus in fetu has been documented only 200 times, but it occurs in one in 500,000 births. This is the first documented case in Hong Kong.”

SOURCES: International Business Times, ABC News, Medical Journal Armed Forces India