British surgeons separate conjoined twins joined at skull in 40-hour 'groundbreaking' operation

Two infant girls born in southwestern Nigeria arrived at Sheikh Khalifa Medical City in Abu Dhabi carrying a condition that kills most children before they ever reach an operating room. Mercy and Goodness were conjoined at the skull—their brain tissue and blood vessels fused together in a way that made them, medically speaking, a single organism in two bodies. They were 19 months old when a team of surgeons decided to attempt what only nine other pairs of conjoined twins have survived: complete separation.

The operation consumed 40 hours across multiple surgical sessions. Twelve doctors and medical staff from Great Ormond Street Hospital in London led the work, joined by more than 50 additional physicians from around the world. The scale of the undertaking reflected both its complexity and its rarity. Before Mercy and Goodness, the Gemini Untwined charity—founded by Professor Noor ul Owase Jeelani, a neurosurgeon at Great Ormond Street—had completed this particular procedure only eight times in its history. The odds they were working against were stark: roughly 40 percent of twins born with fused skulls are stillborn, another third die within their first day of life, and only one in ten million survive long enough to become surgical candidates.

The team deployed technology that would have seemed like science fiction a decade earlier. Three-dimensional models of the twins' skulls were constructed using virtual imaging developed in British laboratories, allowing surgeons to map every vessel, every point of attachment, every millimeter of the separation they would need to perform. Augmented reality techniques guided the actual surgery. Silicone skin expanders were inserted beneath the girls' scalps weeks before the operation, stretching their skin gradually so there would be enough coverage once the skulls were separated and the wound closed. Artificial intelligence assisted in planning and executing the procedure. The combination of these tools produced what Jeelani described as outcomes "not seen before"—a surgery that was simultaneously more precise and less invasive than previous attempts.

The medical team spanned three continents working on behalf of children from a fourth. Jeelani, reflecting on the collaboration, called it "a beautiful example of how we can produce life-changing outcomes through global collaboration and knowledge-sharing: skill, technology and humanity coming together to defy all odds." The language was careful but the implication was clear: this was not routine pediatric neurosurgery. This was the frontier.

Mercy and Goodness recovered fully. They returned to their home in Nigeria as two separate children, each with her own skull, her own blood supply, her own future. The surgery had worked. The separation was complete and successful.

The story carries an echo in another case Gemini Untwined handled in Israel. Two one-year-old girls had been born joined at the back of the head, facing opposite directions—they had never seen each other's faces. After surgery, when they were placed in separate intensive care beds, they became unsettled. But when they were moved close enough to touch, their blood pressure dropped and they calmed. They stared at each other, made sounds, tried to communicate. Dr. Isaac Lazar, the Israeli surgeon involved, described it simply: "It was just so moving." For Jeelani, who witnessed the moment, it crystallized what the surgery meant beyond the technical achievement. "When they could physically touch each other all of a sudden their blood pressure came down and they were much more relaxed," he said. Two children, separated for the first time, discovering each other.