Placenta accreta

Has anyone had a scan that didn’t show placenta accreta but still ended up having it? I had undiagnosed accreta with my first pregnancy and hemorrhaged after birth. With my second I went to a specialist for a scan and they said they couldn’t rule it out one way or another, but everything went smoothly at birth. I’m pregnant with my third baby and my doctor said he didn’t see any signs of accreta on my scan at 28 weeks but I’m not sure how much I can trust that.