Antibiotic Prophylaxis for Abdominal Surgery
Prophylaxis for procedures that involve manipulation of the viscera can be considered
together, as the principles are similar. Adequate concentrations of the antimicrobial
must be present before the time of contamination. A single dose of antibiotic is
usually sufficient, but if the procedure is not completed within 3 hours of initiating
prophylaxis, a second dose should be given if a short-acting antibiotic is used. The
spectrum covered by the antimicrobial must be relevant for the site. The most
common contaminating organisms are aerobic Gram-negative bacilli, eg Escherichia
coli, Klebsiella species and, depending on site and risk factors, anaerobic Gramnegative organisms, eg Bacteroides species.
It has been common practice to avoid prophylaxis for some low-risk procedures such
as appendicectomy and upper gastrointestinal tract surgery or elective
cholecystectomy. In practice, it is very difficult to establish prospectively that any
operation will be a clean procedure, as unexpected pathology may be encountered or
intraoperative contamination may occur. Meta-analysis of trials has shown that
prophylaxis is appropriate in all patients undergoing abdominal surgery.
If peritonitis is detected at surgery or if major peritoneal soiling occurs, the patient
should be given a full course of antimicrobial therapy, see Peritonitis due to
perforated viscus.
Colorectal surgery, appendicectomy, upper gastrointestinal tract or biliary
surgery, including laparoscopic surgery
metronidazole (child: 12.5 mg/kg up to) 500 mg IV, ending the infusion at the
time of induction
PLUS EITHER
1 cephalothin (child: 50 mg/kg up to) 2 g IV, at the time of induction
OR
1 cephazolin (child: 25 mg/kg up to) 1 g IV, at the time of induction
OR
1 gentamicin 2 mg/kg IV, at the time of induction.
Alternatively, as a single drug, use
cefotetan (child: 50 mg/kg up to) 1 to 2 g IV, at the time of induction.
For the following low-risk patients, the anaerobic cover provided by metronidazole
may be omitted:


upper gastrointestinal surgery: patients with normal gastric acidity and
motility, no obstruction, no bleeding and no malignancy or previous gastric
surgery
biliary tract surgery: patients under 60 years of age, nondiabetic and for
elective cholecystectomy with low risk of exploration of the common bile
duct.
Endoscopic procedures
There is no evidence to suggest that patients undergoing routine upper gastrointestinal
endoscopy require antibiotic prophylaxis. However, patients undergoing procedures
that have a higher incidence of bacteraemia, eg those involving the biliary tract,
sclerotherapy, oesophageal dilatation or endoscopic retrograde
cholangiopancreatography (ERCP), may benefit although this is unproven.
1 cephalothin (child: 50 mg/kg up to) 2 g IV, at the time of induction
OR
1 cephazolin (child: 25 mg/kg up to) 1 g IV, at the time of induction
OR
1 gentamicin 2 mg/kg IV, at the time of induction.
Patients with evidence of biliary stasis undergoing ERCP may benefit from an
additional 3 days of oral therapy with amoxycillin+clavulanate (child: 22.5+3.2
mg/kg up to) 875+125 mg, 12-hourly.
Hernia repair
Antibiotic prophylaxis is not recommended for hernia repair without prosthetic
material. Patients at risk of postoperative wound infection, however, may benefit from
antibiotic prophylaxis.
For hernia repair with prosthetic material use antibiotic regimens as recommended for
colorectal surgery.
Key references for this chapter
Revised April 2003. ©Therapeutic Guidelines Limited (etg16, October 2005).