1. Mechanical Bowel Preparation - why bother?
An overview of current evidence and our experience from a 2 year case series
Good afternoon, my name is Tejal Thakar and I’m here to discuss the use of mechanical bowel prep in elective colorectal surgery. I will give a brief overview of the evidence and discuss outcomes at our centre
T Thakar, A Akingboye, R Nadarajah,
F Younis & SV Gurjar
Luton & Dunstable University Hospital

2. What is Mechanical Bowel Preparation (MBP)?
The use of methods to vigorously cleanse the bowel of faecal contents
Aims to minimise risk of septic complications in colorectal surgery, particularly SYMPTOMATIC ANASTOMOTIC LEAK
So this can include any laxative preparations such as moviprep or kleanprep and enemas. The aim is to cleanse the bowel of stools to minimise the risk of complications such as anastomotic leak

3. Traditional Belief REDUCED faecal mass LOWERS bacterial load
LESS risk of spillage & contamination
LESS risk of sepsis and anastomotic leak
…….which makes sense, right?
So the idea is that less faeces means a lower chance of septic complications which seems a logical assumption. Bowel prep became common practice in the late 60s and and evolved into a “standard care” for colon and rectal surgery. A seminal paper from Nichols and Cordon in 1971 lauded its benefits but as early as 1972, a paper from a surgeon called Hughes challenged this belief. and more evidence emerged from studies looking at emergencies and trauma cases in unprepared bowel. This led to randomised trials in elective surgery and over the last 10 years or so we have seen a shift away from the culture of routine mechanical bowel preparation.
BUT THE EVIDENCE TO DATE INCREASINGLY CHALLENGES THIS “DOGMA”

4. The DOWNSIDE of MBP Volume/electrolyte imbalance risk
Inadequate MBP results in liquid stools
May need hospital admission
Time consuming & inconvenient
Nausea, pain, bloating
Mainly associated with polyethyl
glycol or PEG lavage solutions
Patients with cardiac or renal disease are at risk of dehydration and electrolyte imbalance. Inadequate MBP causes liquid stools which are more likely to spill and contaminate the peritoneal cavity. Patients who have specific co-morbidities such as diabetes or those who are elderly may need hospital admission to have their bowel prep administered safely. In addition, the whole process is time consuming and inconvenient as patients are confined to home within easy reach of the loo and they generally feel awful with nausea, pain and bloating. These risks are mainly associated with oral PEG lavage solutions.

5. As you can see, a poorly prepped bowel lumen contains lots of liquid stools which is much more easily spilled when performing a bowel resection rather than lumps of solid stools that can be swabbed away. I’m sure anyone here who performs colonoscopy would find the colon on the left extremely challenging when searching for a polyp or similar.

6. COCHRANE REVIEW 2011 on MBP in elective colorectal surgery
18 randomised clinical trials (RCTs) with 5805 total participants
2906 in Group A had pre-operative MBP
2899 in Group B had none
Primary outcome: Anastomotic leak
Secondary outcome: mortality, peritonitis, re-operation, wound infection
The Cochrane review on MBP in colorectal surgery provides the highest level of evidence we have on the role of mechanical bowel prep in elective colorectal surgery. It looked at 18 randomised trials with nearly 6000 patients who either had pre-operative MBP or they didn’t. It looked at either the primary outcome which was anastomotic leak and secondary outcomes related to sepsis.

7. No statistical significant evidence of benefit from MBP
MBP v no MBP
Group A MBP
Group B no MBP
Total patients in group
2906
2899
Anastomotic leak:
Low anterior resection
Colonic surgery
Overall
8.8%
3.0%
4.4%
10.3%
3.5%
4.5%
Mortality
1.6%
1.8%
Peritonitis
2.2%
Re-operation
6.1%
5.8%
Wound Infection
9.6%
8.5%
The groups were compared and little difference was found between those who had bowel prep with those who hadn’t. There was a further subdivision into surgery involving colo-colonic anastomoses and colorectal anastomosis. It showed there was no statistical evidence of benefit from MBP in patients who had been prepped versus patients who hadn’t.
No statistical significant evidence of benefit from MBP

8. MBP v Enema for Rectal Surgery
Group A
Group B
Total number of patients
601
609
Anastomotic leak:
Low anterior resection
Colonic surgery
Overall
7.4%
4.0%
4.4%
7.9%
2.0%
3.4%
Mortality
1.4%
0.9%
Peritonitis
2.6%
1.9%
Reoperation
3.1%
3.6%
Wound infection
9.1%
8.0%
Five studies were included to enable comparisons between patients who had undergone rectal surgery and had either had full bowel prep or just enemas. There were no studies that totally excluded bowel prep for their regime. Again, it was shown there was no statistical significance between the two groups
No statistical significant evidence of benefit from MBP

9. Conclusions of Cochrane Review
MBP may be safely omitted in cases where lesion can be easily identified
Poor MBP is WORSE than NO MBP
Consider MBP for intra-op colonoscopy or inadequate localisation
Further RCTs needed for laparoscopic & rectal surgery
The conclusion of the cochrane review was that MBP may be safely omited in cases where the lesion can be easily identified. Poor MBP is worse than none at all as the risk of spillage is much higher when the stool is liquid..One would consider pre-operative MBP for intra-operative colonoscopy or if the tumour was not tattooed or very small and hard to find. There was not enough evidence to conclusively say that MBP should be omitted for laparoscopic or rectal surgery.

10. Enhanced Recovery After Surgery Guidelines based on best available evidence to provide optimal perioperative care protocol
MBP should NOT be in routine use for colonic surgery
Pre-operatively tattoo obviates need for MBP in laparoscopic resections
But authors question the wisdom of extrapolating evidence mainly based on open surgery and applying it to laparoscopy
Recommend further research
Enhanced recovery is being increasingly used in the NHS and the guidelines advises that MBP should not be routinely used in colorectal surgery and adopts the view of the Cochrane Collaboration that it should be excluded for pre-operatively marked lesions in laparoscopy. The group accepts the findings of the cochrane review but questions applying all the evidence to laparoscopic colorectal surgeons

11. The Association of Coloproctology of Great Britain and Ireland,
2007 Guidelines on the Management of Colorectal Cancer
Controversially it seems that bowel preparation might lead to more anastomotic leakage and thus the procedure should be omitted…. The rationale for avoiding bowel preparation prior to low anterior resection is less compelling than for colonic resection.
“Bowel preparation should not be used routinely before colorectal cancer resection”
The Association of Coloproctology published its guidelines in 2007 and the bottom line was that bowel prep should not be used routinely before colorectal resection although they feel that there is less of a case for low anterior resections.

12. Retrospective analysis of case series from Colorectal Dept
Aim: to examine our current pre-operative practice for patients undergoing elective left-sided colonic & rectal surgery
So that brings us round to our case series where we looked at patients undergoing elective colorectal surgery

13. Method
Retrospective review of consecutive cases over 2 years reviewed from 2 Consultant Colorectal Surgeons
Low residue diet, senna and enema pre-op
Included
elective left-colonic and rectal surgery
benign and cancer
Excluded
emergencies, Hartmann’s procedures & formation of defunctioning stomas
We retrospectively reviewed consecutives cases over 2 years from 2 consultant surgeons. Patients underwent a protocol of 2 days worth of a low residue diet, 2 doses of senna and an enema only pre-operatively. We incuded….

14. Results Total number of patients 107 Age range 26-86 Average age 57
Benign cases
Cancer cases
23.3%
76.6%
Laparoscopic
84%
Anastomotic leak rate
overall
8.2%
Mortality 0%
Reoperation
8.1%
Infection
Wound
Other site
5.8%
4.6%
Other minor complications 7%
Results
Minor complications: urine retention – 2, ileus – 2, refashion stoma – 1, PR bleed – 1

15. Summary
From our experience, traditional Mechanical Bowel Preparation is not necessary for elective left-colonic and rectal resections. This practice is supported by best available clinical evidence.

16. References
Mechanical Bowel Preparation for elective colorectal surgery (Review) Guenaga KF, Matos D, Wille-Jorgensen PThe Cochrane Collaboration, The Cochrane Library 2011, Issue 9
Guidelines for Perioperative Care in Elective Colonic Surgery: U. O. Gustafsson et al Enhanced Recovery After Surgery (ERAS) Society Recommendations World J Surg (2013) 37:259–284
Guidelines for the Management of Colorectal Cancer, The Association of Coloproctology of Great Britain and Ireland (2007)

17. Thank you