Two types of programs
There are two kinds of program directors here in the US.
Type number 1:
This type is the prevalent type (maybe 70-80% of all programs). They are looking for fresh graduates and they don't want to see old "Experienced" overseas IMGs. Their idea is to bring fresh, unaltered, grads so that they can then mold them the way they want to fit into the US system. They think that if you are so experienced it is hard for them to change your fixed skills and attitudes. Such programs tend to be University based "high profile" programs.
Type number 2:
This is not the prevalent type (maybe 20-30% of all programs). These people recognize and sometimes have high regard to overseas experiences specially if it comes from a high profile prestigious settings (such as John Hopkins affiliated hospitals). They think, why not to take an experienced IMG so that we don't spend time and efforts teaching him/her. Such programs tend to be community based "low profile" programs.
Your obgyn U/S course will certainly help toward the second type but I don't think it will work with the first type (which is, unfortunately, the majority of US residencies).
If you want to enhance your CV to make it appealing for type 1 above then you must have a US clinical experience. Such an experience can be gained by signing up for
paid hands-on externships or by doing
observerships or by doing clinical research.
Another important point, the longer you are away from US the harder for you to get into residencies. Come to USA as soon as you can so that you can jump into the system and flow with it.