Seattle Children’s performs historic 18-hour surgery to separate conjoined twins

An 18-hour surgery involving more than 30 Seattle Children’s Hospital (SCH) healthcare providers successfully separated 15-month-old conjoined twins, SCH announced Wednesday.

After preparation for the surgery began in Oct. 2024, Seattle Children’s successfully performed its surgery to separate the conjoined twins, Ally and El, on February 28, 2025.

“When I met with Dr. Smith and the other Seattle Children’s specialists for a surgery consultation, I knew my family would be in great hands,” Sam, the twins’ mother, said. “Their expertise and approach to care really impressed my husband and me and made our decision to have the surgery at Seattle Children’s an easy one.”

Seattle Children’s conducts 18-hour surgery to separate conjoined twins

In preparation for the lengthy and complex surgery, SCH designated a care team to care for the twins on the day of the surgery, including surgeons, anesthesiologists, and the nursing staff. The team would meet monthly to talk through the flow of the surgery inside the operating room and plan for every detail.

During these meetings, every detail of the operating room was discussed and planned. From the placement of each piece of operating room equipment to the specific instruments needed for the surgery, and potential backup equipment was planned.

“We think about surgery all the time, but this required another level of coordination and teamwork,” said Dr. Caitlin A. Smith, co-director of the Reconstructive Pelvic Medicine program at Seattle Children’s Hospital.

Before the surgery, an MRI, fluoroscopy, and endoscopy were completed to determine a “road map” of the twins’ anatomy and which structures they shared.

While the surgery was underway, incisions were carefully made on each child’s abdomen and pelvis before deeper dissection was performed to separate their gastrointestinal, gynecologic, and urologic systems. Incisions between the twins’ conjoined pelvis were also required to officially separate the two.

“Conjoined twins are rare, and twins joined at the pelvis, as Ally and El were, are even a bit rarer,” Smith said. “The surgery required to separate them is highly specialized, but I was excited because I knew we had the right team in place.”

To perform the reconstruction of each twin, the SCH team placed absorbable mesh, complex soft tissue, and skin coverage with flaps to complete the last stage of the twins’ surgery.

Ally and El’s successful surgery and recovery

Each patient recovered within Seattle Children’s Intensive Care Unit (ICU) before being transferred to the ward.

“The relief that they were separated and safe was incredible,” Smith said. “Each twin got what they needed, thanks to our amazing, dedicated team who worked to ensure Ally and El’s health and safety were priority number one.”

The twins worked with rehab medicine physicians, physical therapists, occupational therapists, and speech language specialists at the SCH inpatient rehabilitation facility prior to their release. In late May, Ally and El were strong enough to leave rehabilitation and continue their recovery at home.

Sessions with SCH therapists will continue as the twins develop their speech, improve their fine motor skills, and strengthen their muscles as they learn to walk.

“It’s incredible to watch our girls crawl quickly, learn new words, and see their distinct personalities take shape,” Sam, the twins’ mother, said. “We are very happy with the care we receive at Seattle Children’s. It was the right decision for our family.”

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