Dr Eugene-Louis Doyen separated conjoined twins in 1902
The death of baby Hope following an operation to separate her from her sister is a reminder that despite advances, the outcome of conjoined twin surgery remains unpredictable.
Even in the modern era, these operations are among the most challenging for doctors, with painstaking preparation involving large teams of specialists.
Only a handful of hospitals in the world have the resources and skills needed to attempt separation.
One of these, Great Ormond Street Hospital in London, worked for more than 12 hours to separate the babies, but Hope's lungs were not sufficiently strong to support her without her twin, and she died shortly after the operation.
Faith, the other twin, faces further surgery to close the large wound in her chest.
Perhaps surprisingly, the history of such operations stretches back more than a century.
Conjoined twins are created just a few days after they are conceived - most likely by the incomplete splitting of the fertilised egg.
Most are stillborn, and a proportion of those who are born alive do not survive long afterwards.
They can be joined at the hip, the back, the chest, or even the head, perhaps sharing one or more internal organs, each adding to the complexity of any operation to separate them, as the surgeon seeks to provide each with enough to support life.
In past centuries, when separation was frequently not an option, there are many references to twins who grew up still joined.
These included two pairs reputedly born in Rome in the fourth and seventh centuries AD and Armenian twins joined at the abdomen in the tenth century AD, alongside the so-called "Biddenden Maids" from England, who were joined at the spine, and reportedly lived into their 30s.
The term "Siamese twins", now discarded, refers to Chang and Eng Bunker, who found fame as circus performers.
While there are reports of unsuccessful attempts to separate twins in the 1600s, what is thought to be the first successful twin separation was carried out in 1689, on twins joined only by a ligament at the chest.
CONJOINED TWINS IN HISTORY
AD 945: Reports of Armenian twins joined at the abdomen
1100-1134: Eliza and Mary Chulkhurst, the Biddenden Maids
1811: Chang & Eng Bunker, circus performers
1878: Rosa and Josepha Blazek - notable German violinists, joined at the spine
While operations on other twins with comparatively simple anatomies were also successful, later attempts to separate those with more shared organs and tissues were frequently only partially successful.
One example is in 1900, with chest-joined Brazilian sisters Maria and Rosalina separated, only for Maria to die within days.
However, by the 1950s, specialists were becoming far more practised, with the first recorded successes in separating twins joined at the skull.
US surgeon Dr C. Everett Koop also managed to separate two girls who shared a bowel, urinary system and genitals - one even managed to go on to mother her own children.
Professor Alastair Millar, from the Red Cross War Memorial Children's Hospital in Capetown, heads a centre responsible for dozens of successful operations in recent years.
He said the key to success in recent years was the ability to plan complex operations well in advance.
"You can now create 3D models on the computer to work out just how you are going to do these operations.
"We are just getting better at everything - the surgical team has been able to discuss what to expect and what role each will play."
However, he said: "In the end, it might not matter how extensively you have prepared, there can always be a surprise for the surgeon when the operation starts, an unexpected complexity.
"And if the operation is an emergency, then the difficulties are far greater."