Frequently Asked Questions
- How common are conjoined twins?
Most conjoined twins do not survive pregnancy. Because they occur so rarely, it is difficult to determine an exact frequency. The occurrence of conjoined twins is estimated to range from 1 in 50,000 births to 1 in 100,000 births worldwide, and the overall survival rate is approximately 25 percent.
- What causes conjoined twins?
There are two theories about the forming of conjoined twins. The first is that a single fertilized egg does not totally split during the process of forming identical twins. The second theory is that a fusion of two fertilized eggs occurs earlier in development. Although conjoined twinning has not been linked to any environmental or genetic cause, because it occurs so rarely, firm conclusions have not been drawn.
- How often is separation surgery performed?
Separation surgery is performed in the United States about six times per year. Most recently, in August, 2011 Great Ormond Street Hospital in London separated one-year-old conjoined twins whose skulls and scalps were fused.
- Has a separation surgery ever been performed at Packard Children’s? What is the history of conjoined twin surgeries in the Bay Area?
Angelina and Angelica Sabuco will be the second set of conjoined twins separated at Lucile Packard Children’s Hospital. Yurelia and Fiorella Rocha-Arias were the first set of conjoined twins separated at the Hospital in 2007. Prior to the opening of Packard Children's in 1991, two sets of twins were separated at Stanford University. Dr. Gary Hartman, the lead surgeon for Yurelia and Fiorella’s separation, was also involved in the prior two surgeries. We do not have details on any other hospitals in the Bay Area separating conjoined twins.
- What experience does the medical team at Packard Children’s have with conjoined twins?
This will be the sixth separation of conjoined twins for lead surgeon Hartman. He has also performed conjoined twin surgeries at Children's National Medical Center in Washington, DC, the University of Oklahoma, and Stanford Hospital & Clinics. Plastic surgeon Peter Lorenz, MD, anesthesiologist Gail Boltz, MD, radiologist Frandics Chan, MD, and many other members of the surgical and care teams have experience separating conjoined twins.
- How are Angelina and Angelica conjoined?
The twins are joined at the chest and abdomen. This type of connection is called thoraco-omphalopagus. Their livers, diaphragms, sterni (breast bones), chest and abdominal wall muscles are fused. They have separate hearts, brains, kidneys, stomachs and intestines.
- What is the survival rate for separation surgeries?
Survival rates for twins joined primarily at the chest, known as thoraco-omphalopagus twins, are dependent on the complexity of the heart connection, if any, and any complications related to the separation of the liver. We expect both girls to survive and recover well.
- Why is Packard Children’s performing this surgery?
Physicians and surgeons at Packard Children’s have carefully evaluated Angelina and Angelica, and determined that in this case a successful separation is possible, which would equally benefit both girls, who face significant musculoskeletal, psychosocial, and other developmental challenges the longer they remain connected. As one of the leading children’s hospitals in the nation, with a strong record of successful outcomes in cases of high acuity, Packard Children’s has the expertise to pursue the best possible outcome.
- What is the cost of the surgery? Who is paying for Angelina’s and Angelica’s medical care?
Packard Children’s does not discuss specific costs of procedures publicly. A portion of the costs will be covered by the family’s insurance plan.
- How old are the twins? Why is this a good age for them to be separated?
Angelina and Angelica are two years old, and therefore stronger and better able to recover after surgery than they would have been as infants. However, their age also means they’ve spent a longer time connected. Some muscle and skeleton changes have probably occurred that may make the actual separation or recovery more difficult.
- When did Angelina and Angelica arrive in the United States? How did they get here?
The twins immigrated to the Bay Area from Manila, Philippines, on September 7, 2010. They contacted Packard Children’s before their move to the U.S., and first met with Dr. Hartman in December 2010.
- What medical care did the girls require before their arrival in the US?
The girls have had standard infant and toddler wellness check-ups and are up-to-date on their vaccinations.
- What tests were performed in the evaluation of Angelina and Angelica?
The girls had an echocardiograph study of the heart using a transesophageal (swallowed) probe. They received basic physical evaluations from physicians in cardiology, plastic surgery and pediatric general surgery. Also, after receiving anesthesia, the girls underwent a computed tomography (CT) scan of the head, chest and abdomen.
- What did tests reveal about the girls’ medical status?
Scans revealed that the girls’ hearts are separate, but may touch at the tips. Their livers are tightly adhered together, with some blood vessels going from one girl's liver to the other. Their intestines appear to touch in some places, but their digestive systems function separately. They lack the sternum bones normally found at the center of the chest; instead, their ribs connect to each other.
- How does the girls’ medical status affect their quality of life presently?
Although they are conjoined, both girls are now essentially healthy two-year-olds. However, they both have musculoskeletal abnormalities that affect the curvature of their spine, and may pose other developmental challenges as they grow. Presumably this would limit their lifespan, but we don’t know what that limitation would be.
- What procedures or treatments were performed to prepare the girls for the separation surgery?
Separating the girls will leave a large skin gap where they had been connected. To prepare for this, four tissue (skin) expanders have been inserted to stretch the girls’ skin so that the surgeons will be able to close the skin after the separation surgery. The girls came to Packard Children’s once a week to have saline injected gradually into the expanders. Each girl will need about 200 square centimeters of new skin to cover the site of the connection.
- What are tissue expanders? How do they work?
The expanders are basically balloons that have a variable capacity based on their design. For Angelina and Angelica, the expanders are all rectangular and will hold a volume of 500 cc (cubic centimeters) of saline (sterile salt water). When fully expanded, the expanders look like soft-drink cans.
- Have the evaluation and tissue-expander procedures provided any valuable insights or lessons for the medical team?
Both were good preliminary procedures for us to learn a lot about how the girls respond to anesthesia and how quickly they recover. Based on these experiences, we expect the risks from anesthesia for their separation surgery to be similar to the risks to any child having major chest and abdominal surgery.
- Who will be involved in this surgery?
Two comprehensive care teams—one for each girl—with representatives from nursing, anesthesia, pediatric general surgery, plastic surgery, and others, will be in the operating room throughout the entire procedure. After separation, the girls will be moved to separate operating tables, with one team moving to an adjacent operating room, and the teams will complete surgery with their respective patients. In addition to the surgical teams, the case has involved radiologists, critical care specialists, infectious disease experts, social workers, recreation therapy and child life experts and many more. Basically every discipline in the hospital will be involved with the girls’ care.
- How does treating a case like this change the usual logistics in the operating room?
In separating conjoined twins, one surgical field becomes two; the surgical team must then divide and treat their respective patients. This requires two complete teams and two complete sets of equipment from the beginning.
- What are the risks for the surgery?
As in any surgery, there are risks, including complications of general anesthesia, bleeding during the procedure and post-surgery infection. In this specific situation, there are additional risks of excess bleeding during the separation of the liver, of injury to the gall bladder and bile ducts, and of respiratory problems due to the reconstruction of the girls’ chest after separation.
- What is the anticipated outcome of the surgery?
The most significant risk is in the separation surgery itself. While it is a relatively risky procedure, there is no evidence to suggest that it cannot be done. The separation surgery performed at Packard Children's in 2007 was more complex than this case because that pair of twins also shared portions of their hearts. Those twins were separated successfully and are now doing well. Packard Children’s anticipates a positive outcome to this surgery.
- Does one twin have a chance for a better outcome than the other?
The girls are estimated to be equal in terms of outcome.
- What will their recovery period be like?
Depending on the course of surgery, recovery will take three to four weeks.
- When will the girls return to their home in San Jose?
Once the Packard Children’s care team feels that the girls are stable, clear of complications, breathing and eating well, they will be free to return home. The Packard care team will remain in contact as necessary.
- Will the girls require any follow-up reconstruction/procedures?
The girls will receive extensive reconstruction of their chest walls, abdominal muscles and skin at the time of the separation. They also will likely need further plastic surgery at the separation site as they grow. The timing of the revision will depend on the degree of scarring they experience and the ways the scars change as they develop.