20 weeks scan. Abnormal cord.

So today I went in for my 20 week ultrasound and the doctor discovered I had an abnormal umbilical cord. Mine seems to be 'unraveled' it goes out in different places into the placenta. Baby is perfect and exactly where he needs to be developmentally so he says not to worry. But he said he's never seen this before. I'll need growth scans every 4 weeks just to check up on it. I was wondering if anyone has heard of this or has had it happen? I could really use some reassurance. Thank you!