I had what is probably my last ultrasound (and a half) last week, at nearly 35 weeks. It was an eventful one (and a half). Tuesday morning, my in-laws were heading out of town after spending a weekend, and I had invited them to come to my appointment, as they'd never seen more than the crummy black-and-white alien photos from ultrasounds. They got quite a show.
It turns out that my son's 2-vessel cord looks like a 2/3 vessel cord in spots. The ultrasound tech got a shot of the cord close to the baby, where there appeared to be 2 arteries and 1 vein, all in normal proportions. But much of the cord still shows only 2 vessels. She brought in my OB, who said that he'd never heard of or seen such a thing before. Both of them were a bit giddy--and talked about possibly publishing what they were seeing. Also, she noted that the baby's estimated weight was 6lbs 4oz, putting him in the 80th percentile based on gestational age....he was 40th 2 months ago, and 56th 3 weeks ago. Apparently, however many blood vessels he has, he's getting plenty of nutrients....
When I returned on Friday afternoon for my regular NST, the ultrasound tech grabbed me for some additional photos of the cord. She'd started doing a little research already and had found few or no references to umbilical cords where a vessel is either collapsed or forked or something. She did double-check the cord entry point to the bladder, and there it appears to be a true 2-vessel cord.
In any case, this doesn't really change much. I'm still on the 2x a week plan for NST's. My birth plan still hasn't changed (though the possibility of a 9lb baby does make the whole VBAC thing sound rather...um...eventful). After the baby is born, they will be examining his cord in a lab setting. I have no problems with any sort of publishing in medical journals...I'll have to remember to ask the OB to send me a copy of anything they do write, for the scrapbook :)