At 4 weeks pregnant they won't be able to tell much at all, even looking at her cervix. Every woman's cervix is different during pregnancy.
i told her she might be further along because 8dpo is really early to get a bfp... so they wont see anything on the ultrasound
Most likely they won't be able to see anything at 4W pregnant, I was 6W3D at my first ultrasound and I just barely saw anything, so make sure she doesn't panic if there's nothing visible, it can take up to 7-8W to see anything.