WASHINGTON (AP) -- Surgeons successfully separated 4-month-old conjoined twin boys Wednesday night, the lead surgeon declaring, "They are two separate individuals."
"Both are doing well," said the surgeon, Robert Keating. "All of the vital signs are doing well."
The separation took place about 12 1/2 hours after the first incision Wednesday morning.
Keating cautioned that the boys, Mateo Asher Shaw and McHale Twain Shaw of Sheboygan, Wis., still have several hours of surgery in separate operating rooms, where they were to undergo reconstruction and have large wounds closed.
"They have a fair amount of defects," he said, such as exposed muscle. And he said it will be days or weeks before their recovery can be gauged.
Earlier in the day, the surgeons successfully separated the twins' spinal cords but kept their shared tailbone intact temporarily because of the stability it provided to surgeons as they repositioned the boys.
Following that, surgeons had to separate the boys' muscle, tissue and gastrointestinal systems.
The twins were born May 10 joined at the lower back with conjoined spinal cords.
The boys' parents had been receiving periodic updates and passing the time in a hospital waiting room.
"It's been a roller-coaster," the boys' mother, Angie Benzschawel, 25, said in an interview earlier in the day. "You have a mix of every emotion possible -- pretty much the worst
"But lack of sleep helps," quipped the boys' father, Ryan Shaw, 28.
Family members and friends also congregated in the room, killing time by playing Monopoly.
Shaw said that the unknowns are the hardest part.
"You don't know what's going to happen," he said. "You don't know how long the surgery's going to be, you don't know if one boy's going to come out walking, or both of 'em are going to come out walking, or neither of 'em -- you just don't know."
Shaw sported a green T-shirt with the words "Feelin' Lucky?"
"I'm kind of a superstitious person," he explained.
Both parents warmly embraced security guards as they returned to the room after getting an update from doctors.
"We've been here since April," said Benzschawel. "The hospital staff is almost like another family. We couldn't get through it without them."
They were also comforted Wednesday by Melissa Buckles, whose conjoined twins were separated at the same hospital two years ago.
More than 65 people worked on the operation, including doctors, nurses and staff.
Conjoined twins occur about once in every 50,000 to 100,000 births. Only about 20 percent survive to become viable candidates for separation.
In Salt Lake City, doctors at Primary Children's Medical Center performed additional surgery on 4-year-old Kendra Herrin, who was separated from her twin sister, Maliyah, last month in a 26-hour operation. Kendra Herrin started showing signs of a bowel obstruction that doctors believe may have been caused by scar tissue.
The Shaw twins' family has set up a fund for the boys called the Mateo and McHale Shaw Fund, in care of the Kohler Credit Union, 850 Woodlake Road, Kohler, Wis., 53044.