Very wierd you should say this...ive just got back from Hospital following a referral for a reassurance scan after my 3/4D scan at the weekend.
The 3D/4D scan pics show what i describe as a crater (!!) on my babys head. Sounds like you are describing similar.



I was worried so called the 4d scan lady who initially thought it was where the cord is lying but then offered to refer me to Hosp for a reassurance scan.
Today at Hosp they scanned me in 2D and said everything is measuring fine, and if I hadn't shown them my 3d scan pics, they would have sent me away without a second thought. However, on closer inspection, they said they could see something on the forehead, but they just aren't sure what!
Consultant is referring me to fetal medicine dept at Newcastle RVI for a 3D scan so they can get a better look at what it is. He suggested a bit of thickening of the skull, or perhaps even lots of hair which is giving that effect.
Hopefully its nothing to worry about, everything was finbe at 20 weeks, I am now 27/3.
My scan at Newcastle is 3rd March so I'll be worrying until then.
They going to scan you further? How have they left it with you?
xxx