HONG KONG, Feb. 9 (UPI) -- Doctors in Hong Kong report in a newly released study that said they removed two fetuses from the abdomen of a 3-week-old girl who was found to have been born "pregnant."

Dr. Yu Kai-man, a specialist in obstetrics and gynecology at Queen Elizabeth Hospital, said tests were performed on the newborn when a pair of tumors were detected in her abdomen and doctors determined the growths were actually twin fetuses weighing 14.2 grams and 9.3 grams after 8 to 10 weeks of gestation.


Yu and colleagues wrote in a study published in the February issue of the Hong Kong Medical Journal the fetuses each had an umbilical cord connected to a single placenta-like mass in the girl's abdomen. The discovery was made in November 2010 and fetuses were removed from the infant's abdomen.

"It was almost impossible to detect during the prenatal checkup, as the embryo inside the baby was too small," Yu said. "Since it is impossible for the little girl to have conceived the pregnancy on her own, the fertilization of the twin fetuses, of course, belongs to her parents, which has gone to the wrong place."

Yu said the condition is known as "fetus-in-fetu" and occurs about once in every 500,000 births, with fewer than 200 cases reported in literature.

The doctors said the condition is classified by the World Health Organization as a mature teratoma, a type of cancer, but the cause is unknown.

"The widespread use of antenatal ultrasound in early gestation may provide more concrete evidence ... and shed light on this intriguing condition," the doctors wrote in the study.