I am 19 weeks pregnant with a 3mm thick uterus , dr was very worried . anyone else had this ? Thanks?

Hi I just had my ultrasound at 19 weeks and every thing looks good til the dr noticed I had 5 previous c-sections and this will be the 6th so she staarted checking on the placenta and uterus wall more and she sorta freaked and said my uterus wall was only 3mm thick already and that I could not have more children and she was going to call my OB right now and she left ! The ultra sound tech finished up and I left felling very confused and to tell you the truth from her reaction worried . Has anyone elso run into this and what has you out come been . I really appreciate all you time . We tried so hard for a year to get pregnant with this baby and I don't want to worry if there is not a definite reason to . Thanks