BACKGROUND Anal abscess and perianal fistula is a high prevalence disorder in general
population that affect adult patients on young ages, affecting them significantly their
social and quality of life. There is clinical evidence that the origin of most perianal
fistulas (60%) is with an episode one year before of a perianal abscess. In fact, the
established cryptoglandular hypothesis considered the origin of anal fistula, a chronic
infectious disease starting on a clinical episode of an anal glands abscess. However,
controversy exists regarding the role of antibiotics in the development of anal fistula after
incision and drainage of perianal abscess. Nowadays, only two single-centre randomized
controlled trials has been published addressing this issue, with inconclusive results. The
MAIN OBJECTIVE of the study is to examine the clinical benefit of antibiotic therapy in
patients with a perianal abscess, to avoid the development of a perianal fistula. METHODOLOGY
We designed a prospective, multicentre double-blind placebo trial to analyse the clinical
benefit of a course of antibiotics after perianal abscess drainage to diminish the
probability of development of perianal fistula in the follow up of patients. Patients with
anal abscess will be allocated randomly either to receive 7 days of oral
metronidazole/ciprofloxacin in addition to their standard care or to receive standard care
and placebo, after they will be discharged from the hospital. Patients will be followed
clinically at different intervals during one year in order to know if they develop anal
fistula. Also a quality of life assessment at the end of the study will be evaluated.
EXPECTED RESULTS We expected that patients allocated to antibiotic treatment would develop a
significant less anal fistulas in their follow-up with a related significant better quality
of life. Thus, a change on standard of care led by our group, may be achieved.