No written rule but ...
There's no written rule that says research is mandatory to get into general surgery residency but the reality is that if you don't have you won't be able to compete with the thousands of other IMGs who have research and applying with you.
To give you an idea:
I have a friend who finished 10 years of extensive surgical training and experience in his home country. He has over a dozen of research publications in his name and thousands of operations in his CV.
He applied for general surgery this year and he got only 8 interviews
I have another friend who has 4 years of general surgery training in his country and did 4 months of observership in USA and applied this year. He got only 3 interviews
Another issue that I'd like to remind you about. There's no Hands-On surgical rotation in USA. You can't do that when you are an IMG with no residency training in USA.
I also would like to refer you to this poll
http://www.usmle-forums.com/externs...externship.html?highlight=research+externship