boy's blood supply was going actually to his twin. and it was relatively balanced. so blood was coming in, and it was going partially to their brother. and you can imagine if you tie off your drainage of blood from your brain, your brain will get swollen and could become severely damaged. so we were concerned. we didn't know exactly how the brain would reroute the blood. >> the surgeons believe that small blood vessels will take up the flow and do the job. but these vessels are so minuscule they can't even be seen on scans. still, the surgeons are cautiously optimistic. on october 4th, 2003 the twins' mother, sabah, arrives in dallas after not seeing her boys for 16 months. the surgery is only a week away. this is the moment about which she has been dreaming. >> translator: whenever i go to bed at night, i feel that they are both with me but separated, not joined.