Saline Sonohystergram Questions?

I think the question I am about to ask is normal but I still want to be sure. Two days ago I got a Saline Sonohystergram from my doctor and today and yesterday I have had fairly heavy brown  discharge. Is it normal for this to continue two days after the procedure? I know they said there would be spotting I just wasn't sure how long it was supposed to last. Please any help or information is appreciated. Thank you.