Dec 23, 2012 11:00 AM by Michelle Castillo - CBS News
Recently separated conjoined twin girls Allison June and Amelia Lee Tucker had their first public appearance at the Children's Hospital of Philadelphia on Thursday.
The 10-month-old girls had been joined at the lower chest and abdomen in a condition known as an omphalopagus connection. They shared a chest wall, diaphragm, pericardium and liver before the surgery. Allison was discharged on on Dec. 17, but Amelia will require a longer stay into the new year.
"Both Allison and Amelia are doing well, and we expect them both to enjoy full, healthy and independent lives," Dr. Holly L. Hedrick, the pediatric general, thoracic and fetal surgeon who led the Children's Hospital of Philadelphia surgical team, said in a press release.
The two sisters underwent the separation surgery when they were 8 months old on Nov. 7. About 40 medical professionals assisted in the seven-hour procedure. They were the 21st pair of twins to be separated at the hospital.
Prior to the surgery, the girls had spent their whole lives at the hospital. For their first seven weeks, they lived at the Harriet and Ronald Lassin Newborn/Infant Intensive Care Unit (N/IICU) and then moved to a surgical step-down unit.
Months before the separation, plastic surgeron Dr. David Low put skin expanders in both girls to increase their skin surface so they could cover the areas that would be left open after the surgery.
"Like all separations of conjoined twins, this was a very complex surgery, but it went very well and as expected," Hedrick said in a press release at the time.
Most scientists believe that conjoined twins occur when one fertilized egg divides into two fetuses but does not separate, according to the Mayo Clinic. Identical twins become connected, with how far the egg splits being the determining factor of where the connection will be.
According to the University of Maryland Medical Center, conjoined twins make up one out of every 200,000 live births. Only 5 to 25 percent of conjoined twins survive, with 40 to 60 percent of conjoined twins born stillborn and 35 percent living for only one day. Females make up 70 percent of conjoined twins, and are three times more likely to be born alive than their males.