40 week growth scan?

Aly • ITS A BOY 🍼💙
How accurate are scans at 40 weeks. At 36 weeks baby measured 7 pounds. I went to a scan 40+2 and was told baby was 10 pounds. I was also told I should consider a c section. Just seems unlikely that baby grew that much. Could him being a long baby throw off the weight? 😩😩😩😭