Antibiotic treatment following surgical drainage of perianal abscess: a double-blind, placebo-controlled,
randomized trial.

Perianal fistula is a burdening disease with an annual prevalence of 2/100.000
in the Dutch population.
Treatment is often difficult and in case of high complex fistula more than 50%
of patients undergoes more
than 2 operations with still variable results. Every year, in the Netherlands,
more than 5000 operations are
carried out for perianal fistula. Consequences for social and work life is
considerable and therefore presents
an economic burden. More than 90% of crypto-glandular fistulas originate from
anorectal abscess (Sainio).
Despite adequate drainage of anorectal abscess up to 83% recurs or results in
an anal fistula, the majority
developing within 12 months (Oliver). Meticulous preoperative diagnosis and
concomitant antibiotics are
attempts to reduce this undesirable course but evidence of its effect is
scarce. There is some evidence that
gut derived bacteria play a role in development of a perianal fistula
(Hamadani, Fielding). Up till now it is not
common practice to routinely administer antibiotics. A systematic review of 6
studies found a decrease of
incidence of anal fistula development when surgical treatment of perianal
abscess is accompanied by
antibiotics (Mocanu). However, this review includes 6 studies of which most
have a retrospective nature
and only 2 are randomized controlled trials. International guidelines
addressing treatment of perianal
abscess recommend drainage and in case of immunosuppression or systemic illness
addition of antibiotics
(Vogel, Malik); level of evidence is low (2 C). The Dutch Guideline does not
specifically address treatment
of perianal abscess. Further high quality studies are required to clarify the
effect of antibiotic treatment in
addition to drainage of perianal abscess. Reports of costs and cost-
effectiveness of treatments for patients
with anal fistula are scarce. Only one recent Swedish study investigated
disease-associated costs and
concluded that the burden on society is high which justifies all attempts to
reduce occurrence (Lundqvist).
Prevention by treating perianal abscess adequately would contribute in this
attempt. A trial comparing
efficiency of adequate drainage of perianal abscess followed by postoperative
antibiotics vs drainage
followed by placebo drugs is warranted.

This study has been transitioned to CTIS with ID 2024-517233-40-00 check the CTIS register for the current data.

The objective of this trial is to establish if adding antibiotic treatment to
surgical drainage of perianal
abscess results in less perianal fistulas.

The study concerns a double-blind, placebo-controlled, randomized, multicenter
trial with treatment of
perianal abscess by surgical drainage alone or combined with antibiotic
treatment.

Patients were randomly allocated to 1 of 2 groups (antibiotics or placebo). The
antibiotic group received 7
days of oral metronidazole (500 mg every eight hours) and ciprofloxacin (500 mg
every twelve hours) in
addition to surgical drainage. The other group received surgical drainage and
postoperatively identical
placebo tablets prepared by the pharmacology department of Amsterdam University
Hospital during 7 days.
Surgical drainage is performed by a colorectal surgeon or resident under
general or local anesthesia. The
patient is placed in lithotomy position and the rectum is first examined. The
abscess is incised and
adequately drained. The abscess cavity is debrided. The rectum is checked for
an internal opening. The
wound is left open for secondary healing. When possible pre-or peroperative
diagnostics will be done by
either (endo-)ultrasonography or MRI.

Questionnaires at 5 different time points - baseline, 1 week, 3 months, 6 and
12 months postoperative. (5 x 10 minutes). Extra visit at the outpatient clinic
at 12 months.