Hi Motherluch! I had a fistulotomy on June 27th. I had a low, superficial fistula (it was actually caused by my LIS incision healing over, and so it had to be deroofed

). I'm one month post-op and healing well (KOW!).
I think a lot depends on how high the fistula is. From what I've read, high ones that involve a lot of muscle require a seton, but lower ones that don't involve a lot of muscle can just be laid open with a fistulotomy. Maybe you should ask your CRS's for more information about what kind of fisula you have. From what I understand, there a different kinds of fistulas:
Superficial fistulas don’t involve sphincter muscles; intersphincteric fistulas form at the “intersphincteric plane” (between the internal and external sphincter muscles); trans-sphincteric fistulas travel from the intersphincteric plane and go through external sphincter; suprasphincteric fistulas penetrate the sphincter muscles and go around the external sphincter; and extrasphincteric fistulas connect the rectum to perineal skin but pass external to sphincter. I’ve pasted a link below to a website that I found helpful for understanding different kinds of fistulas. The low ones (superficial and intersphincteric) are the most common.
http://www.medscape.com/viewarticle/475289_3As Val suggests, new knowledge develops all the time, and good surgeons keep up with things, so I think this is definitely something to ask your surgeons more about.
I hope this helps!