What does it mean if there is an impression of a bicornuate or septated uterus?

This is a good question, and I'm surprised there is not more information about this for women.

A uterus is normally shaped like a triangle when looking at the outside, and inside, the uterus is also shaped like a triangle.

A bicornuate uterus is shaped like a Y, with a part to the left and a part to the right. From the outside, the top is indented, and also looks like a Y shape.

A septate uterus is also shaped like a Y, but has a septum in the middle partially dividing the uterus. From the outside, the uterus looks normal (is not indented).

Here are some pictures, that will be more helpful: http://infertilityblog.blogspot.com/2007/02/bicornuate-or-septate_06.html

Can you tell us more about your condition, and what prompted the MRI test to be done? Are you trying to conceive, or have any other questions? What has your doctor said about this condition, and what further tests are they suggesting? I assume the "impression" of one of these conditions means that they have not done a diagnostic test (to look inside the uterus, to see if there is a septum dividing/partially dividing the uterus), and that they only noticed on the MRI that your uterus was partially over to one side.