Anal fistulas continue to be a problem for patients and surgeons alike despite scientific advances. While patient and anatomical characteristics are important to surgeons who are evaluating patients with anal fistulas, their development and persistence likely involves a multifaceted interaction of histological, microbiological, and molecular factors. Histological studies have shown that anal fistulas are variably epithelialized and are surrounded by dense collagen tissue with pockets of inflammatory cells. Yet, it remains unknown if or how histological differences impact fistula healing. The presence of a perianal abscess that contains gut flora commonly leads to the development of anal fistula. This implies a microbiological component, but bacteria are infrequently found in chronic fistulas. Recent work has shown an increased expression of proinflammatory cytokines and epithelial to mesenchymal cell transition in both cryptoglandular and Crohn's perianal fistulas. This suggests that molecular mechanisms may also play a role in both fistula development and persistence. The aim of this study was to examine the histological, microbiological, molecular, and host factors that contribute to the development and persistence of anal fistulas.

Healing rates following sphincter-sparing repairs of cryptoglandular anal fistulas are modest, but have improved over time with the use of better surgical techniques. In this study, ligation of the intersphincteric fistula tract and flaps were superior to fistula plugs and fibrin glue; the former procedures are therefore favored. See Video Abstract at http://links.lww.com/DCR/A391.

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Magnetic anal sphincter augmentation provided excellent outcomes in patients who retained a functioning device at long-term follow-up. Protocols to reduce early complications will be important to improve overall results.

Bio-Thiersch as an adjunct to perineal proctectomy may reduce the risk for recurrent rectal prolapse and can be particularly effective in patients with a history of previous failed prolapse procedures.