First successful separation of conjoined twins
Catherina Meinin, Elisabet Meinin, Johannes Fatio
first first
Switzerland (Basel)

The first recorded successful separation of conjoined twins was carried out by Swiss surgeon Johannes Fatio in Basel, Switzerland, between 24 November and 3 December 1689. The patients were a pair of newborn girls named Elisabet and Catherina, both of whom recovered fully from the surgery.

Elisabet and Catherina were born to 42-year-old Clementia Meinin (or Meijerin) on 23 November 1689. The twins were examined by a group of Basel physicians, who reported that their bodies were fused together between the xiphoid process (a section of cartilage at the base of the sternum) and the navel. Their umbilical cords, which contained three large blood vessels from each child, were also fused.

The surgery was performed in two parts. Fatio's first task, undertaken on 24 November, was to dissect the umbilical cords, cutting the shared blood vessels and ligating them with silk thread. With this accomplished, he looped a strong silk ligature around the band of tissue connecting the two girls and gently tightened it. Over the following days, the ligature was progressively tightened, with the necrotizing tissue being treated with alcohol. On 3 December, the connection between the twins was severed and the stumps of the join dressed and treated. The twins were reportedly fully healed and feeding normally within two weeks.

The first published accounts of the procedure were written by Emanuel König and Theodor Zwinger in 1689 and 1690 respectively. Both were eminent physicians and eyewitnesses to the event. Fatio wrote his own account, but was executed during a period of political violence before he could publish. His book was eventually printed in 1752.

There is one earlier recorded case of surgery to separate conjoined twins, but this attempt was only partially successful. As described in the works of Leo the Deacon and other contemporary chronicles, there was a pair of conjoined twins in the mid ninth century who travelled around the Byzantine Empire. Around 945 CE, one of the twins died during a visit to Byzantium (present-day Istanbul) and physicians severed the connection between the living twin and his dead brother. The separated twin only lived for another three days, however.