Conjoined twins Maria & Teresa Tapia: Before and after

Meet Maria and Teresa Tapia, 19-month-old twins who were conjoined - until their separation surgery on Monday, Nov. 4. How common are conjoined twins? They account for between 1 in 50,000 and 1 in 100,000 live births worldwide. About a half-dozen separation surgeries are performed in the U.S. a year, according to the twins' doctor, Dr. David Lanning.

The girls, from the Dominican Republic, were separated at the Children's Hospital of Richmond at Virginia Commonwealth University. Keep clicking to hear their story, as reported by the Associated Press, and see pictures before and after surgery...

Maria and Teresa were born joined at the lower chest and abdomen, sharing a liver, pancreas and portion of the small intestine.

The twins meet with surgeon-in-chief Dr. David Lanning prior to surgery. In several procedures involving six surgeons, the medical team divided the liver, pancreas and other shared organ systems and reconstructed the girls' abdominal wall.

How did the operation go? "Everything just went so smoothly over the last 24 hours," said Dr. Lanning.

Because of the way the top portion of their small intestines were connected, Maria wasn't able to absorb the nutrition she needed and was about 20 percent smaller than Teresa. Also, nearly 88 percent of the liver's blood flow was routed to Teresa.

Dr. Lanning is a surgical volunteer for the non-profit World Pediatric Project, who sponsored the twins' medical care and the family's stay in the U.S.

Teresa (left) and Maria get a kiss from their mother, Lisandra Sanatis. The girls and their mother arrived in Richmond two months before the surgery to prepare.

The twins and their family have become celebrities in the Dominican Republic. The country's first lady, Margarita Cedeno de Fernandez, stopped in Richmond on Monday during the surgery to support them.

Here is the family during a special visit the day before the surgery from Dr. Margarita Cede

Medical personnel weren't the only ones to help out the twins. The university - performing its first ever separation surgery - allowed students from different departments to get involved. For example, fashion students created new outfits for the toddlers, an occupational therapist modified a car seat, and a sculpture student created foam models of the twins' bodies so surgeons could practice on synthetic skin before the operation.

Professor Kristin Caskey (left) and student Mariah Harrison during a sewing workshop dedicated to creating clothing for the twins.

Sculpture students Kristi South (left) and Morgan Yacoe hold plaster molds they made of the conjoined twins' torso region. The molds helped plastic surgeons determine the best way to cosmetically care for the twins following separation.

Here are the girls with program director Kim Gottwald at the Children's Hospital.

The girls' mother said she has always dreamed of seeing her daughters as independent children. Teresa is more tranquil and Maria is more forceful and tough, she said.

Sanatis predicted that her daughters will be glad to be able to get away from each other during arguments. "They fight like siblings who aren't conjoined fight," she said. "But imagine if you have nowhere to go."

Maria (left) and Teresa moments before surgery.

During the operation.

Mom holds Maria's hand for the first time after the separation.

Maria (right) and Teresa play at the hospital, after their successful separation.

Maria (right), the smaller of the two, weighs about 19 pounds, and Teresa weighs about 26 pounds. The disparity in their weight, caused by the configuration of their small intestines and blood flow from the liver, will gradually even out, Dr. Lanning said.

The girls were scheduled to leave the hospital Friday, Dec. 1 - but they're not heading back to the Dominican Republic yet. The toddlers will remain in Richmond as they undergo therapy to relearn walking and otherwise reorient their movements now that they're no longer attached.

After being in Richmond for several months now, Sanatis says she and her daughters are more than ready to leave the confines of the hospital and are anxious to return to their family in their native country. "We're missing our family, and the girls miss their little brother, Lisander," she said.

Sanatis with Teresa (left) and Maria at the hospital.

Sanatis with Teresa (left) and Rocio Watson, of the World Pediatric Project - the group that helped sponsor the operation - with Maria.