I am in the process of preparing for a colectomy (I've had all the tests and flunked with flying colors!). I just completed 3 months of biofeedback, which didn't help at all, and I have an appt. on July 31 to discuss moving forward with the surgery. I have lived on laxative for 30 years...no kidding. If I don't take a laxative, I don't go. Period. I'm 52 years old, and even before I started taking senna every 4 or 5 days to clean me out (30 years ago) I was miserable....took enemas, ex-lax, feenamint, you name it, I took it. I've told every Dr. I've had about this my entire life and most of them just said to drink more water and exercise. Anyone with this problem knows that in a perfect world that would work, but not for us.
My surgeon knows my history of senna, and didn't tell me there was a 50% chance of being incontinent at all. He said there could be complications, but his experience is (he is a colon surgeon) that after a year, every patient he's had said they were sorry they waited so long to have the surgery.
I was told 25 years ago I would probably need this surgery one day. 3 years ago I went to another colon specialist and without all the testing, he said I needed a colectomy. I refused to believe it. Last Xmas I had a terrible experience though, and I swore I was going to do something about this. I had all the necessary tests, am trying biofeedback, may have the STARR procedure for a rectocele, and hopefully can wait until the first of the year to have the colectomy. I had tests done on my small intestine and it seemed to work ok...just not the large.
I doubt seriously that taking senna for 6 months will make much difference in the outcome. You should talk to your surgeon about it, but my surgeon told me he hears our story often...and that usually if you have colon inertia, you need a colectomy before you're 40. He said I was lucky laxatives worked as long as they have for me.
Good luck; I'd be interested in hearing what your Dr. says about your laxative use.