Mechanical Bowel Preparation and Use of Oral Antibiotics

Discussed measures with variable recommendations

Why mechanical bowel preparation (MBP) is not recommended alone

Mechanical 1

“Mechanical bowel preparation without oral antimicrobials does not decrease the risk of SSI.”1

The question of how best to prepare the bowel of patients prior to elective colorectal surgery has long been debated. Practice ranges from MBP alone, MBP combined with preoperative oral antibiotics (OA), …intravenous antibiotics (IV) combined with oral antibiotics and enema, …to the exclusive administration of intraoperative venous antibiotics.2,3

Handling in practice seems to vary widely worldwide and also depends on the surgical site (colon or rectum) and the approach (open or laparoscopic).2,3

Therefore, the current recommendations of the various professional societies do not present a uniform picture.1,4–7 The tendency is toward a combination of MBP and antibiotics.4,5,7




Category (if mentioned)


“1. Administer a prophylactic antimicrobial agent only when indicated, and select it based on its efficacy against the most common pathogens causing SSI for a specific operation and published recommendations.”

Category IA

“2. Administer by the intravenous route the initial dose of prophylactic antimicrobial agent, timed such that a bactericidal concentration of the drug is established in serum and tissues when the incision is made. Maintain therapeutic levels of the agent in serum and tissues throughout the operation and until, at most, a few hours after the incision is closed in the operating room.”
“3. Before elective colorectal operations in addition to 2 above, mechanically prepare the colon by use of enemas and cathartic agents. Administer nonabsorbable oral antimicrobial agents in divided doses on the day before the operation.”
“4. For high-risk cesarean section, administer the prophylactic antimicrobial agent immediately after the umbilical cord is clamped.”
“5. Do not routinely use vancomycin for antimicrobial prophylaxis.”Category IB


“The panel suggests that preoperative oral antibiotics combined with mechanical bowel preparation (MBP) should be used to reduce the risk of SSI in adult patients undergoing elective colorectal surgery.

Conditional recommendation,
oderate quality of evidence

“The panel recommends that MBP alone (without administration of oral antibiotics) should not be used for the purpose of reducing SSI in adult patients undergoing elective colorectal surgery.”Strong recommendation,
moderate quality of evidence


“Do not use mechanical bowel preparation routinely to reduce the risk of surgical site infection.”



“Use a combination of parenteral antimicrobial agents and oral antimicrobials to reduce the risk of SSI following colorectal procedures.


(i) The additional SSI reduction achieved with mechanical bowel preparation has not been studied, but the data supporting use of oral antimicrobials have all been generated in combination with mechanical bowel preparation.
(ii) Mechanical bowel preparation without oral antimicrobials does not decrease the risk of SSI.”


Commission recommends mechanical bowel evacuation in conjunction with oral antibiotic administration before colorectal surgery.

Category II

Most recommended instructions

Current evidence on the combination of oral and intravenous antibiotics with or without MBP2

A network Meta-analysis from 2022 investigated the ranking of different bowel preparation treatment strategies for their association with postoperative outcomes.


“The addition of oral antibiotics to intravenous antibiotics, both with and without MBP, was associated with a reduction in incisional SSI by greater than 50%.”

Greater than 50%

Results of a European survey from 20173

In 2017 an online survey to members of the European Society of Coloproctology was circulated regarding the practice of bowel preparation in colorectal surgery.


  • 29.6% prescribe MBP routinely prior to colonic surgery
  • 77.0% prescribe MBP routinely prior to rectal surgery
  • 19.7% performing colorectal operations laparoscopically use MBP
  • < 10% prescribe oral antibiotics
  • 96% prescribe perioperative intravenous antibiotics

Possible harms of the intervention of MBP5

There are some harms formulated by the WHO that may be associated with MBP at the time of anesthesia and incision:

  • Patient discomfort
  • Electrolyte abnormalities
  • Potentially severe dehydration

HARTMANN: food of thoughts

Endogenous pathogens from the skin or gastrointestinal tract are the most frequent causing postoperative SSI following abdominal surgery.8

Wound edge protectors and surgical wound irrigation should therefore be additional tried and tested measures for reducing SSI.8,9
Click to see full list References

1Anderson DJ, et al. (2014) Strategies to Prevent Surgical Site Infections in Acute Care Hospitals: 2014 Update. Infect Control Hosp Epidemiol 35(6): 605–627.
2Woodfield JC, et al. (2022) Stategies for Antibiotic Administration for Bowel Preparation Among Patients Untergoing Elective Colorectal Surgery. A Network Meta-analysis. JAMA Surg 157(1): 34–41.

3Devane LA, et al. (2017) A European survey of bowel preparation in colorectal surgery. Colorectal Dis 19(11): O402–O406.
4CDC (1999) Guideline for Prevention of Surgical Site Infection. Infect Control Hosp Epidemiol. 20(4): 247–278.
5WHO (2016) Global guidelines for the prevention of surgical site infection. World Health Organization 2016.
6NICE (2020) Surgical site infections: prevention and treatment. NICE guidelines. Published: 11 April 2019. Last updated:19 August 2020.
7KRINKO (2018) Präventionpostoperativer Wundinfektionen.Empfehlungen der Kommission für Krankenhaushygiene und Infektionsprävention (KRINKO) beim Robert Koch-Institut. Bundesgesundheitsbl 61: 448–473.
8Mihaljevic AL, et al. (2015) Wound Edge Protectors in Open Abdominal Surgery to Reduce Surgical Site Infections: A Systematic Review and Meta-Analysis. PLoS ONE 10(3): e0121187.
9Strobel et al. (2020) Reduction of postoperative wound infections by antiseptica (RECIPE)? Ann Surg 272(1): 55–64.

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