Conjoined twins Addison (Addy) and Lilianna (Lily) Altobelli were successfully separated by surgeons at Children’s Hospital of Philadelphia (CHOP) on October 13, 2021. The girls were born connected at the abdomen and chest, a condition known as thoraco-omphalopagus twins, meaning they shared a liver, diaphragm, chest and abdominal wall.

Addy and Lily’s journey began when they were diagnosed prenatally at their 20-week ultrasound. Before that appointment, parents Maggie and Dom Altobelli had assumed they were having one baby, but the ultrasound image showed that not only was Maggie carrying two fetuses but they were also attached at the abdomen.

Conjoined twins are rare, occurring in only about 1 in 50,000 births. The couple was referred to CHOP for further evaluation, since the hospital is one of only a few in the country with experience separating conjoined twins. More than 28 pairs of conjoined twins have been separated at CHOP since 1957, the most of any hospital in the country.

The couple met with specialists in CHOP’s Richard D. Wood Jr. Center for Fetal Diagnosis and Treatment. Doctors discovered that although the girls shared a chest and abdominal wall, diaphragm, and liver, the twins had separate, healthy hearts. Their shared liver was also large enough to divide between them, making them excellent candidates for separation surgery.

After months of planning for a high-risk delivery via C-section, led by Julie S. Moldenhauer, MD, Addy and Lily were born on November 18, 2020, in the Garbose Family Special Delivery Unit (SDU), CHOP’s inpatient delivery unit. They spent four months in the Newborn/Infant Intensive Care Unit (N/IICU), followed by six months in the Pediatric Intensive Care Unit (PICU). CHOP plastic surgeon David W. Low, MD, inserted skin expanders to stretch the girls’ skin in preparation for separation surgery. Like small, collapsible balloons, the skin expanders gradually expand through injections, stretching the skin slowly over time so each girl would have enough skin to cover her exposed chest wall and abdomen after separation.

On October 13, 2021, after months of preparation, Addy and Lily underwent a 10-hour surgery and were officially separated at 2:38 p.m. The surgical team, led by Holly Hedrick, MD, included more than two dozen specialists, including general surgeons, anesthesiologists, radiologists, a cardiothoracic surgeon, and plastic surgeons. Once the twins had been separated, the surgical team rebuilt each girl’s chest and abdominal wall. Stephanie Fuller, MD, a cardiothoracic surgeon, ligated the girls’ patent ductus arteriosus and made sure both girls’ hearts were in the right position and functioning well. Plastic surgeons placed two layers of mesh – one temporary, one permanent – over the twins’ abdominal and chest walls and then covered that with the skin that had been stretched over months.

On December 1, 2021, the Altobellis finally flew home to Chicago – one twin at a time, with one parent each – after living in Philadelphia for more than a year. The twins spent two weeks at Lurie Children’s Hospital under the care of the medical team that will support them closer to home. The girls were discharged just in time for Christmas and arrived home to find their yard decorated by their neighbors. They spent the holiday together at home as a family of four.