Anal fistula surgery is judged largely by continence outcomes, because the tract often crosses sphincter fibres. Modern minimally invasive options were specifically designed to avoid cutting muscle.
$\textbf{LIFT}$ works in the intersphincteric groove, ligating the tract on either side without sacrificing sphincter bulk. $\textbf{FiLaC}$ delivers $360^\circ$ laser energy that shrinks and seals the tract lining while the muscle stays intact. $\textbf{VAAFT}$ uses direct endoscopic visualisation to destroy the tract and securely close the internal opening, again without dividing sphincter.
By contrast, $\textbf{fistulectomy}$ surgically excises the fistula as a block of tissue; because the tract physically runs through sphincter, removing it typically sacrifices muscle and threatens continence. It is therefore the odd one out.
\[\boxed{\text{Fistulectomy is NOT sphincter-preserving}}\]