Twins Born Inside Their Sister



In Hong Kong’s Queen Elizabeth Hospital, a mother gave birth to a 9-pound baby girl who had interred her siblings inside of her body. In this unusual case of twins born inside their sister, the infant had surgery at three weeks old to remove the two fetal masses. After eight days in the hospital, she returned home to her family on mainland China. The medical rarity was written up in the Hong Kong Medical Journal.

The phenomena of fetus-in-fetu occurs once in every 500,000 births with only 200 cases ever reported.  Both fetuses looked to have a gestational age of eight to 10 weeks. When babies such as this are born, they can present in many different ways. In the case of the twins born inside their sister, the baby girl had a mass of fetal tissue between her liver and left kidney, inside her body cavity. The obstetrician knew that there were two separate fetuses because when he removed them, he found two separate partially-formed fetal structures. Each fetal structure had its own spine, intestine and brain matter. This led study authors to believe that the woman was likely pregnant with triplets, where the surviving baby absorbed the other two fetuses. They also hypothesize that she may have had more than one previous abortion. Another theory is that the mass was a teratoma, a non-cancerous tumor containing tissue, hair, and even teeth.

twinsTeratomas or dermoid cysts are common and occur in women between 15 and 40 years of age.  However it is quite rare for twins to be born inside their sister. Many people who have dermoid cysts do not know it. Often the germ cell consisting of tissue, hair, and teeth lie dormant in the female’s body. Symptoms that are often overlooked include a dull, throbbing pain in the lower back or thigh or difficulty urinating. It is usually when the teratoma continues to grow that it twists the ovaries, causing extreme pain in the side or lower back.  This type of situation always warrants emergency surgery to remove the dermoid. Sometimes the fallopian tube and the ovary must also be removed.  As was the case with the twins born inside their sister, the germ cells to create such an anomaly were present inside the baby at birth. If it were not removed at birth, the teratoma would have remained inside of the baby, but would have to be excised later.

Dermoid cysts can present inside the mouth, on the eyelids and on the head. Removal of these external cysts is routine and relatively easy. In 25 percent of cases, dermoid cysts present internally. They usually sit at the tip of the ovary tube, making removal of this benign tumor easy with laparoscopy. Still, care must be exercised because if the cyst has bacteria within, it can spread to other bodily cavities upon removal.  Doctors make every attempt to preserve the ovaries if a woman is of childbearing age. Even if one ovary must be removed, the other ovary still has the ability to ovulate, menstruate, and even conceive. Twins born inside their sister is rare and likely the reason why the Hong Kong case was written up in the medical journal.

By Danielle Branch



Go Ask Alice

Health Grades

ABC News

Photo by Danny Cain – Flickr

Photo by Tatiana Vdb – Flickr

Leave a Reply

Your email address will not be published.