Every few months it seems another pair of conjoined twins makes international headlines.
This time it's Kendra and Maliyah Herrin, who were separated late Monday after more than a day of extensive surgery. The 4-year-old girls, from North Salt Lake City, were born fused at the chest, sharing several organs and a set of legs.
The harrowing stories of conjoined twins may garner lots of interest, and certainly trigger lots of hope, but the long-term outlook for most of them is for the most part unpredictable. Conjoined twins who survive beyond birth are so rare, and all so medically different, that generalizing or speculating about their prognosis after separation is a gamble, doctors said.
In many ways, it's still the Wild West of medicine, where doctors operate without the benefit of years of experience about what works. At the same time, emotions run high, since the patients are usually children with one of the oddest birth defects known to exist.
"We're so used to reading about the tremendous trials of thousands of patients and FDA approval of this drug and that device, and this just comes down to one step above bedside manner," explained Dr. David Staffenberg, chief of pediatric plastic surgery at the Children's Hospital at Montefiore Medical Center in the Bronx, N.Y.
What is known: Most conjoined twins are born stillborn or die within days after birth, and of those who do survive past the first few days of life are usually female, for unknown reasons. The easiest to separate are twins fused at the chest but who don't share a heart. The most difficult to separate are twins fused at the head, because of the vast blood supply in the brain, according to a fact sheet from the Johns Hopkins Children's Center.
But perhaps most important, twins who are separated generally do better than those who are left fused, which puts the impetus on surgeons to come up with newer and better ways to perform the often unimaginably challenging separation surgeries.
Staffenberg was one of the lead physicians who several years ago helped separate Carl and Clarence Aguirre, toddlers who were not only fused at the head but shared brain material. The neurological damage that could occur during separation was staggering.
Unlike cases of years past, the doctors believed that for Carl and Clarence, both could be saved. So, the focus became not which twin should live but how to do as little brain damage as possible. His team decided on an innovative, staged approach, in which surgeries were done over a series of months.
"At the beginning, I sat down and began to draw things out. There came a time when you had to stop thinking about it. It seemed infinitely complicated," Staffenberg said.
These days, both twins seem to be doing well. Both can walk, but Carl's neurological development has been slower than his brother's.
Staffenberg said that, like many people, he avidly follows conjoined twins' stories, such as the recent separation of the Herrin twins in Utah. What he found most amazing about them was that they actually expressed a desire to live separate lives, he said. That alone means surgery should be seriously considered.
Still, while the medical heroics are inspiring, the high mortality rate mean parents, loved ones and even the millions of people following conjoined twins' sagas should realize the enormous risks involved, noted Dr. Marcelo Cardarelli, director of pediatric cardiac surgery at the University of Maryland Medical Center in Baltimore.
"The issue, No. 1, is we tend to put them all in one bag, but they [all conjoined twins] are very different among themselves," Cardarelli said. "The cases are so few and infrequent, and the mortality rate is between 40 and 90 percent, that, at the end, you end up with a handful of cases that have survived surgery. I think you can count maybe 100 separation surgeries of conjoined twins in the whole world."
Cardarelli helped separate Loice and Christine Onziga of Uganda, who were born connected from the breastbone to the navel. They had several fused tissues, and their hearts were linked by a large blood vessel. Their recovery has been excellent.
All things considered, the Onzigas' separation was relatively uncomplicated, although nothing is easy when dealing with conjoined twins, especially the ethical issues, Cardarelli noted.
"More often, we're doing things because we can. Unfortunately, that doesn't mean we should," he said. "As a society, we value individuality. We can't comprehend not to be an individual."