Hi Woi - I just wanted to say that I had an anterior fissure and the LIS healed it right up, no leakage or anything. So I agree with the others that you should probably get a second opinion.
I've read that women's sphincter muscles are weaker in the anterior area because of the way we are built (and so docs are quite careful especially with women who have given birth, which I have not). But I do think that a surgeon who knows what s/he is doing would not have a problem dealing with an anterior fissure.
Of course, the Nif could certainly work, in which case you can by-pass that whole surgery thing (fingers crossed!!!). But if that doesn't happen, I really don't think that you are SOL. There's always hope. :)
I hope you're feeling a bit better.