A British surgeon has successfully performed a gruelling operation to separate 19-month-old conjoined twins who were attached at the skull. 

The twin girls, Mercy and Goodness, from Nigeria, are said to have made full recoveries and have returned home following the complex procedure.

The 12-hour surgery took place at Sheikh Khalifa Medical City in Abu Dhabi and was led by Professor Noor ul Owase Jeelani, a paediatric neurosurgeon at London’s Great Ormond Street Hospital.

He previously helped separate one-year-old twins Minal and Mirha from Pakistan in 2024.

The latest operation, carried out last year, involved an international team of medics from the UAE, the UK, Brazil and Nigeria. 

It is believed to be the fastest recorded separation of twins vertically conjoined at the head.

The girls and their parents travelled to Abu Dhabi for the life-changing procedure, which was carried out under the supervision of doctors from the UK-based charity Gemini Untwined and UAE healthcare provider PureHealth.

Professor Jeelani, who led the surgery and founded Gemini Untwined, said: ‘The separation of Goodness and Mercy is a landmark case planned and executed with a level of precision not encountered before.

'Building on the experience of our previous eight cases, and using novel techniques and strategies, we are able to give these girls and their family a new future.  

The full treatment spanned four months and four days, involving four separate operations, more than 40 hours in theatre, and over 60 healthcare staff from 20 different nationalities.

The procedure was particularly high risk because the twins shared vital blood vessels and brain tissue due to their fused skulls - a rare condition known as craniopagus.

Months of preparation went into the separation, including the use of 3D imaging, virtual reality simulations, augmented reality overlays and ultrasound-guided tissue expansion.

These technologies allowed surgeons across multiple countries to map the twins’ complex vascular and neural systems in a shared virtual environment.

The surgery has been described as one of the most complex of its kind, involving techniques developed over 18 years of similar cases.

One of the key innovations used was the ‘open book technique’, which relies on gravity rather than steel retractors to prevent brain collapse and reduce trauma.

Ahead of the final stage, doctors inserted silicone expanders beneath the twins’ scalps to stretch the skin, ensuring there was enough to cover their skulls after separation.

With the help of AI modelling, these expanders were placed earlier than in previous cases, removing the need for skin grafts.

Mercy and Goodness, who were born in June 2023 in Nigeria’s Ekiti State, were referred to Gemini Untwined at six months old.

The organisation is the only charity in the world dedicated exclusively to treating craniopagus twins.

The surgical team included specialists from the UK, Brazil and the UAE, alongside a 12-person multidisciplinary team from Great Ormond Street Hospital.

Conjoined twins occur in around one in every 2.5 million births, with only five per cent involving fusion at the skull.

According to Great Ormond Street Hospital, around 40 per cent of craniopagus twins are stillborn or die during labour, while a further third die within 24 hours.