Bowel Preparation Before Colonic Surgery

Core Recommendations

The ERAS Society recommends mechanical bowel preparation (MBP) combined with oral antibiotics plus intravenous antibiotics for elective colonic surgery, particularly in patients with comorbidities like impaired renal function who require careful fluid and electrolyte management 1, 2
The American College of Surgeons suggests that MBP alone with only systemic antibiotic prophylaxis should NOT be used routinely in colonic surgery as it provides no clinical advantage and causes dehydration and discomfort without reducing surgical site infections, anastomotic leaks, or mortality 1, 2
The combination of MBP + oral antibiotics + intravenous antibiotics reduces surgical site infections (OR 0.63), anastomotic leaks (OR 0.60), ileus (OR 0.79), and major morbidity (OR 0.73) compared to no preparation 1

Patients with impaired renal function must reach the operating room in a euvolemic state with corrected fluid and electrolyte deficits, and intravenous fluid therapy is mandatory when MBP is used to compensate for deficits and improve outcomes 1, 2
MBP may be advantageous in rectal surgery, particularly when a diverting stoma is planned, to avoid retained stool in the diverted colon 1, 3

The ERAS Society recommends intravenous antibiotics to be given within 60 minutes before incision to all patients 3
Oral antibiotics should be given in combination with MBP for aerobic and anaerobic coverage 3
Anaerobic coverage is critical—single-agent first-generation cephalosporin without anaerobic coverage increases SSI risk from 12% to 39% 4

Clear fluids are permitted until 2 hours before anesthesia, and light meals are permitted up to 6 hours before surgery 1, 2
Carbohydrate loading (800ml evening before, 400ml 2-3 hours before induction) reduces insulin resistance and improves metabolic outcomes 1, 2
Avoid prolonged preoperative fasting, and provide clear liquids including carbohydrate drinks to reduce preoperative fluid deficits 1, 2

Using MBP alone without oral antibiotics provides no benefit and causes harm through dehydration 1, 2
Inadequate fluid replacement in patients receiving MBP, especially those with renal impairment, can lead to complications 1, 2
Omitting oral antibiotics when MBP is performed can increase the risk of surgical site infections 1, 3
Failing to give IV antibiotics within 60 minutes of incision can increase the risk of surgical site infections 3
Using inadequate anaerobic coverage can dramatically increase SSI risk 4