Going into the operating room that day, Dr. Allan Goldstein knew that one of the baby girls on the table would probably die.
The girls were conjoined twins, just 22 months old.
In any surgery, doctors hope the patient will emerge in better shape than when they went in. But that day, for the first time in his career, he was faced with dividing life in two, and possibly ending one.
"We as doctors do everything in the best interest of the patient," says Goldstein, the surgeon-in-chief at the MassGeneral Hospital for Children in Boston.
"But in this case, what's in the best interest of one patient may not be in the best interest of the other."
The girls had come to Boston with their parents, from their home in a village in East Africa.
"They were stigmatized because these children did not look normal," Goldstein says.
People would throw rocks at the children whenever their parents took them outside in public, he adds.
'She was active, energetic, she loved to play with the doctors and nurses. Twin A was smaller, more subdued, less active.' - Dr. Allan Goldstein
The family was not only persecuted for having the children, but for seeking medical help to, as Goldstein puts it, "undo what God had done by trying to separate them."
The Current is not naming the parents, who cited fear of the safety of themselves, their children and their relatives still in Africa.
"The girls were what we call omphalo-ischiopagus," he says. "That means that they were attached that the abdomen and the pelvis."
"They had two heads and two chests and then the rest of the body was a single body, although it had three legs — they had four arms."
Upon the first meeting, it was clear to Goldstein that he was dealing with two distinct individuals, even though they shared one body.
"One was very playful," he says, referring to the child known as Twin B.
"She was active, energetic, she loved to play with the doctors and nurses. She also played with her sister although her sister, who we refer to as Twin A, was smaller, more subdued, less active."
Initial scans gave doctors hope that the twins could be successfully separated, but Goldstein soon made a discovery which raised a new set of questions.
The twins shared non-vital organs: intestines, one liver, one pelvis, one bladder, colon, rectum, anus and vagina.
"All of that can be separated and you can even reconstruct those organs in the other twin," Goldstein says.
'The parents were clear that they wanted both to live, but if they both couldn't live, they wanted at least one to live.' - Dr. Allan Goldstein
However, problems arose when he looked at their hearts.
"While Twin B had a relatively normal heart, [Twin A's] heart was very abnormal."
Twin B's heart was essentially providing Twin A with life support.
"Twin B's heart, which was very healthy, was pumping blood through a large artery that went from the aorta of Twin B over to the aorta of Twin A," he says.
"Without that life support, Twin A would have already died long before."
Goldstein was now faced with the possibility that trying to help the twins had a high probability of killing at least one of them.
He and his team now had to decide whether the operation, while feasible, was the right thing to do.
The pediatric ethics committee reviewed the case, trying to frame the problem in ways that could help both the doctors and the parents make their decision.
'If we did nothing the smaller twin would clearly die.' - Dr. Allan Goldstein
Eventually, it all boiled down to one big question: Is it ever morally acceptable to sacrifice one child for another, and if it is, who should make that decision?
"We talked to the parents at length," Goldstein says, "and came to the conclusion that if we did nothing the smaller twin would clearly die."
Twin A was getting sick, and if she died, the toxins and chemicals released would "certainly" kill Twin B.
The prospect of losing both twins led Goldstein to the conclusion that they should act.
The family agreed.
He says the parents understood the risks.
"The parents were clear that they wanted both to live, but if they both couldn't live, they wanted at least one to live," he says.
Goldstein and his team began preparations for the extremely complicated surgery, putting together a team of almost 150 people.
He had hoped to spend a couple of months meticulously planning — the 12 surgeons involved, the order they worked in, the logistics, the post-op care.
But then Twin A got so sick that the girls ended up in intensive care, and Goldstein's team had to push the operation forward.
For the day of the surgery, Goldstein booked three operating rooms.
One was for the separation surgery itself. The second was where they hoped to treat Twin A if she survived. And the third was for the enormous medical team to rest, during their parts of the 14-hour surgery.
On the day of the operation, the first step was getting the twins to sleep and inserting breathing tubes and IV lines. That alone was a tricky prospect given their small body, and how closely they faced each other.
The team also had to figure out where to make the incision.
"Knowing that Twin B is hopefully going to survive, you can't use any of Twin A's skin, because it won't be provided with blood by Twin B's heart," Goldstein explains.
"So we need to know which skin is provided blood by which baby's heart."
'We knew that the moment we divided it, Twin A would likely die.' - Dr. Allan Goldstein
Plastic surgeons injected a fluorescent dye into Twin B's blood. Using a special monitor, they could see which parts of the girls' skin lit up, and therefore belonged to Twin B.
"That let us get into the abdomen to separate the liver," Goldstein says.
"Next we divided the intestine. We were able to separate all the abdominal organs and then the orthopaedic surgeons came and dealt with the pelvis."
Then came the hardest part of the operation: dividing the artery that was supplying blood from Twin B's heart to Twin A.
"We left it for last because we knew that the moment we divided it, Twin A would likely die."
Once the artery was divided, Twin A's blood pressure dropped significantly, as well as her oxygen level.
"She died within 10 minutes of dividing that blood vessel," Goldstein says.
The girls were separated, and the plastic surgeons stayed with Twin B to seal her up.
Goldstein took Twin A into the second operating room, and prepared her body so that her family could come to say goodbye.
Then he went into the third operating room, and cried.
Goldstein says he'll never know if the decision they made was the right one.
"If they were adults we would ask them: 'What would you like to do?'" he says.
"If asked: 'Do you want to be separated or do you want to die together?' maybe the weaker twin would have said 'No, it's best that my my sister live on.'"
"I'll never know. I hope that we made the right decision. The parents feel that we made the right decision and that was very important."
Twin B is doing well, he says. She's now three-and-a-half.
She has an unusual defect with her leg — a duplication where her foot has a central big toe and three smaller toes on either side — which will require surgery if she is ever to be able to walk.
"But amazingly her bowel function is normal, her urinary function is normal," he says.
"She's incredibly fun, she's always smiling."
"She has wonderful parents who take care of her. She really looks, if you just looked at her, she looks entirely like a normal child."
On the day of the surgery, the girls' mother stayed with Twin B in the intensive care unit, while the father buried her sister.
They're afraid to go home to Africa after the persecution they faced, but are comfortable with the decision they made.
Since then, Goldstein says, they haven't looked back.
He says they're thrilled to have their beautiful daughter with them.
"When she came early on for a post-operative visit — it must have been just a few months after surgery — I gave her a stuffed animal, a teddy bear, as a gift," he recalls.
"She was really happy, and she said something to her father. And I asked him what she said.
"And he said: 'She said it's her sister.'"
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This segment was produced by The Current's Alison Masemann.