September 8, 2015 10:32 AM EDT

A team of American doctors have successfully separated conjoined twin girls during a 16-hour operation on Thursday.

The girls—Acen and Apio—from Uganda, are 11 months old. They had been joined at the pelvic and hip region.

They’re expected to make a full recovery, according to a press release from Nationwide Children’s Hospital in Columbus, Ohio.

“Because of the delicate job our neurosurgeons had of separating the spinal cord, our team was assisted by neurophysiologic intraoperative monitoring and the technicians were able to tell us which muscles and nerves belonged to Acen and which belonged to Apio,” Dr. Gail Besner, chief of Pediatric Surgery at the hospital, said, noting the girls were referred to as as “blue” and “red” to eliminate confusion. “This is the first time this specific type of monitoring has been done in a conjoined twins’ separation surgery.”

The girls were flown to Nationwide Children’s, where four conjoined twins have successfully been separated, in December. Earlier this year, they had a preliminary procedure to place tissue expanders beneath their skin to prepare for the impending separation.

Acen and Apio will require one more surgery, but the complex procedure has been deemed a success.

“I can’t wait to watch them grow,” Besner said. “My hope is that they will be able to sit up on their own, walk and play like any other child.”

One in every 200,000 pregnancies result in conjoined twins.

Write to Tanya Basu at tanya.basu@time.com.

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