I had LIS surgery in 2005 after suffering from two fissures, a sentinel skin pile, etc. I had a fissure that would appear every so often for years before it got really bad.

Surgery was a success, and I don't have any issues with pain or bleeding now, etc.

But I sometimes notice that if I strain a bit while having a bowel movement, one side of the stool, especially at the end, is flat. Not the entire stool, just the part at the end if I strain a bit (if I eat enough fiber, my stool looks totally normal).

I have always assumed this was from the surgery--a kind of scar, or maybe changes in the muscle tissue. Nevertheless, it is a bit strange.

So I figured I would ask others here that have had LIS surgery. Have you seen this?

My guess would be that it is an internal hemorrhoid (they don't hurt). They do block the passage somewhat though, hence the flat shape where the stool passes them. I had huge internals before my hemorrhoidectomy, and my stools always came out flat on three sides (triangular). I also had LIS surgery, btw, and the shape of my stool didn't change at all from that.