During the operation, surgeons tried to keep a constant blood flow to the twins' brains. They diverted the shared blood vessel to one brain, and used a vein from the thigh of one twin as a replacement vessel for the other brain. At one stage, this vein became blocked, but doctors managed to clear it.

Then the surgeons carefully began separating the brains, cutting through tissue and teasing out tangled nerve connections. Although Ladan and Laleh had separate brains, they had become fused together over time, which made the procedure more difficult.Things got more complicated when the sisters' blood pressure became unstable.