Conjoined twin girls in Texas to undergo separation surgery

The Mata twins, Knatalye Hope and Adeline Faith, were born via Caesarian section on April 11 at 3:41 a.m. at Texas Children's Hospital in Houston, weighing just 3 pounds and 7 ounces. The girls share their loving parents but also a liver, diaphragm, pericardial sac (the lining of the heart) and intestines. Doctors have now begun the difficult work of figuring out how to separate them.

Last January, Elysse Mata and her husband, John, learned the babies were conjoined during a routine ultrasound. Their obstetrician referred the couple to Texas Children's Fetal Center, where the mom-to-be underwent extensive imaging tests. A team of doctors consulted with the couple on plans to safely deliver the babies and provide appropriate postnatal care.

Due to their early delivery, the twins were born with premature lungs and some other organs that were not fully developed, which meant doctors wanted to give them time to grow and become stronger before attempting any surgical procedures.

The girls now weigh 11 pounds each and are currently being cared for at the hospital's level IV neonatal intensive care unit. The medical team expects to perform separation surgery on the twins when they're 6 to 8 months old. Right now they are focused on ensuring the twins continue to grow and stay healthy.

To prepare for the separation, the first procedure will involve placing "tissue expanders" below the skin which will help it to stretch gradually and encourage skin growth. Doctors will need extra skin in order to successfully complete the surgery and stitch up the chest cavities of both babies. This process is expected to take 6 to 8 weeks, after which time the medical team will move ahead with the operation to separate the sisters.

"The separation will involve many surgeons including those from pediatric general surgery, urology, plastic surgery, orthopedic surgery, cardiac surgery and gynecology," said Dr. Darrell Cass, pediatric surgeon and co-director of Texas Children's Fetal Center, in a statement. "We will have two 'teams' of surgeons. One team will start, and then once the babies are separated the two teams will separate to work on each infant, and finish the reconstruction."

Survival rates of conjoined twins tend to vary depending on where on the body the babies are fused and which vital organs they share. This is what primarily determines whether or not it's safe to conduct surgery. With advances in surgery, successful separation of conjoined twins has become more common.

Scientists say conjoined twins are the result of one fertilized egg that divides into two fetuses that fail to fully separate. Conjoined twins are incredibly rare, which is why they tend to make headlines. Approximately one of every 200,000 deliveries are conjoined twins. Among those, only 35 percent survive past their first day in the world. The overall survival rate of conjoined twins is about 5 to 25 percent.

The medical team says the surgery will come with some level of risk. The parents could lose one or both of their girls, though their doctor says this outcome is unlikely.

In the future, the girls are likely to need orthopedic surgery to help them walk. Additionally, the doctors anticipate a number of plastic surgery procedures may be necessary. But overall, they are optimistic about the girls' chances.

"I am expecting each child to be able to live independently and to have a very good life," said Cass.