How accurate is abdominal ultrasound?

[Hopefulmi]

I had a private ultrasound 23rd dec as I was worried about pancreatic cancer due to to back pain. They said it might be obstructed view due to being 28 weeks pregnant but then the sonographer said she could see pancreas clearly. Everything looked fine as it did on my 2 u/s in January. However the one in January measured my common bile duct at 2.6 mm and this one measured it at 3.1!

Is u/s accurate and is a difference in measurement like that significant?

[Hopefulmi]

Does anyone know?

[Traceypo]

I don't hun, you've got to trust the experts in reading these things.
Xx