I had a ct & 2 past transvag. ultrasounds that said my uterus is normal.had a ultrasound last week that noted a bicornuate/seperate uterus. could it be wrong?how could this be missed on my past tests?

Not perfect tests: It is quite possible to miss things on these tests. A ct scan sees slices and an ultrasound sees blurry echoes. I had a patient that had a ct scan that missed 2 brain aneurysms prior to shock therapy. Her skilled doctor had it repeated after she had a nosebleed after one bout of shock treatment. Only one was seen on the second ct and the second on MRI prior to neurosurgery.

Mri is best: Due to the fact that contrast between any fluid in your uterine cavity, endometrium, and uterus wall is not ideal on ct and us, a uterine variant such as a septum could be missed, especially if it is thin or short in length. The gold standard imaging method for evaluating uterine morphology and variants is mri.

It was missed : This was likey missed on ultrasound, it can be easily missed. Depending on the ct imaging it can also be missed in that. If you want a definite answer you could get an MRI with contrast.