Conjoined twins Uwenzile and Uyihlelile Shilongonyane from the Kingdon of Swaziland, who were born on Jan 2, 2017, have been successfully separated in a six-hour operation at Netcare Unitas Hospital in Centurion, about 50 kilometres north of here.

The twin girls, who together weighed 4.21 kilogrammes at birth, were born joined at the abdomen to 19-year-old Bongekile Simelane and her husband, Mbongeni Sihlongonyane.

Speaking ahead of Saturday's procedure, paediatric surgeons Dr Mariza de Villiers and Dr Paul Stevens agreed that the twins had a good prognosis. "This type of conjoined twins are known as omphalopagus twins, which means they were joined at the lower abdomen and do not share a heart," they added.

"Pre-operative assessments indicated that the babies also did not share any other vital organs. This considerably improved their chances of surviving the surgical separation and will also contribute greatly to them leading healthy lives going forward," said De Villiers.

The Shilongonyane girls are the second set of conjoined twins that De Villiers and Stevens have separated and are the first to have their separation surgery done at Netcare Unitas Hospital.

De Villiers said the twins were joined only by a bridge of skin which made the operation simpler than if they shared vital organs.

"There are always considerable risks when separating conjoined twins, but we have been cautiously optimistic all along that the operation would have a good outcome for both twins. The fact that there was a skin bridge between them meant that there was sufficient skin to close the resultant surgical wound on each baby without the need for plastic surgery," she said.

Stevens said one of the main problems the surgical team anticipated ahead of the procedure related to the anaesthesia. "The twins were conjoined in such a way that they are facing each other. Intubation for such tiny babies is delicate enough, but as their faces are so close to one another and they are not able to be placed on their backs to be intubated for anaesthesia this was a great deal more complicated than usual," he said.

The initial stage of the procedure, which was dedicated to getting the anaesthetic just right for the surgery, took more than three hours, which meant that it took almost half of the total theatre time. The twins were officially separated at noon on Saturday and the rest of the surgery was completed just before 2 pm.

The babies were born by caesarean section. Bongekile and Mbongeni are also parents of twin boys aged two. Bongekile said she had no idea that she was carrying twins until the seventh month of her pregnancy.

"At first I was not happy to hear that I was expecting twins for the second time. However, once they were born everything changed. After their birth I was at first not worried as I thought the babies were only attached at the umbilical cord. I love my babies so much," said a tearful and nervous Bongekile as the babies were taken into theatre.