msm, if you're inflamed, it's hard to retain the enemas. I have noticed that enemas usually require a bit of discomfort but I am able to hold them in all night if I can relax and breathe deep for the first 5 minutes. After that time, I am fine. If I am flared up badly, I won't even try to use an enema because I can't retain them. Those times, I opt for suppositories. I have been in flares so bad that I couldn't retain a suppository. In those cases, I think steroid foam is easier to retain since it almost dissolves in the rectum.
I wouldn't give up on the rectals. It may be some trial and error to find what works for you. if you're not able to retain Rowasa, you could try Canasa AM & PM.