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Bowel prep- yes or no?
Ian BotterillDept Colorectal Surgery
St James’ University HospitalLeeds
Goligher (1970’s)“…there are great advantages to operating on an empty colon
…if the growth is stenotic, 10-14 days should be set aside
… excellent preparation may be obtained with 30l via the irrigation machine
…my preference is 5-6 days, initial softening then vigorous expulsion with castor oil
… finally, massive colonic irrigation in the terminal phase
….this process can be exhausting for frail, elderly patients
….some suggest that it may lead to hypovolaemia and circulatory imbalance”
Surgery of the Anus, Rectum & Colon 3rd edition 1975
Heresy….
• Irving et al 1987 (BJS)
- retrospective, uncontrolled study- no bowel prep
- 72 1y anastomoses- no leaks- 8% wound sepsis
The BJS response
“this paper which challenges accepted surgical practice, is a veritable little bomb of a paper, brief, iconoclastic and disrespectful of hallowed tradition in surgery”
Professor David Johnston, BJS 1987;74:553-4
Justification for using bowel prep
• Poor mechanical bowel prep associated with anastomotic dehiscence1
• “Notwithstanding recent publications ….intuitively it is unfathomable to believe that stool does not have deleterious effect on a healing anastomosis” 2
1 Irvin, Goligher BJS 1973;60:461-4
2 Surgery for the Colon, Rectum & Anus 2nd ed. Gordon & Nivatvongs. 1999
Downside of bowel prepHypovolaemia
- ↓ cardiac output / shock- ↓ coronary artery filling- colonic mucosal ischaemia
Electrolyte disturbance- fits- dysrhythmias- myopathy- nausea
Diarrhoea- lack of sleep &vitality
Colonic explosion
Bowel prep- creation of a need for ‘pre-optimisation’?
• Pts undergoing major elective surgery (large DGH)
• Randomised to :- standard care
- HDU pre-optimisation (fluids +/- 2 inotropes) guided by PAFC / CVP
• Active treatment group-required 1.5l IV fluid
-↓ M&M & ↓ LoS
Wilson et al. BMJ 1999;318:1099-1103
Cochrane review 2004
• Inclusion criteria - randomised clinical trials, elective surgery - leak rate (1y outcome) clearly stated
• Stratified (where possible)- low anterior resection- colo-colic / intra-peritoneal anastomosis
Cochrane review-2y outcome measures
• Mortality
• Peritonitis
• Re-operation
• Wound sepsis
• Extra-abdominal (infectious / non-infectious)
• Total infection rate
Recruitment to Cochrane review
• Oral bowel prep (+/- enema) versus nil• Standard meta-analysis methodology
Studies included / excluded
• 14 studies identified- 5 excluded: no control (3)
elemental diet in controls (1) ill-defined outcomes (1)
• 9 included - 7 english / 1 spanish / 1 portugese - 3/9 abstracts - 9 trials: 789 oral prep / 803 no oral prep
Cochrane review: problems….
• Power calculation0/9
• Intention to treat analysis0/9
Cochrane review-casemix of included studies
• No anastomosis - 2/9 included pts without an anastomosis - 2/9 included pts ultimately not anastomosed
• Preoperative radio / chemoradiotherapy - 0/9 studies reported use
• Antibiotic prophylaxis - 2/9 did not describe use
• Demographics- 3/9 did not describe demographics / operation- 1/9 described significant diff’s
Cochrane review:-exclusion criteria in the papers
• No description of exclusion criteria (4/9)
• Recent antibiotics / bowel prep (3/9)
• Failure to tolerate prep (2/9)• No anastomosis performed (2/9)
Potential bias in included papers (1)
• None used ITT analysis-3/9 withdrew pts after randomisation (5%,31%,10%)
• Selection bias: 5/9 randomisation not described
• Blinding: 8/9 not blinded
• Performance bias: nil detected
Potential bias (2)
• Attrition bias:
-4/9 did not describe withdrawls
• Detection bias-4/9 did not describe diagnostic processes
• Reporting bias- 5/9 no stratification of leaks into anastomotic subgroups
Results: 1y outcome measure (anastomotic leak)
Low rectal
colon total
Bowel prep
9.8% 2.9% 6.2%
No bowel prep
7.5% 1.6% 3.2%*
*p=0.003
2y outcome measures
• Focal peritoneal sepsis -5.7% (bowel prep) -2.5% (no prep)
p=0.05
• Other 2y endpoints- no significant differences
Sensitivity analysis
• Exclusion studies with inadequate randomisation- OR unchanged, significance lost (T2 error)
• Exclusion of studies in abstract form- no effect
• Exclusion of study including children- no effect
• Exclusion of studies including no anastomosis - ↓ OR of leak 2.1 (2.3) p=0.03
Length of stay?
• Multimodal peri-operative recovery package
• Managed care pathways
Henrik Kehlet 24hrs & 48hrs post sigmoid colectomy
L.o.S. only quoted in 1/9 articles reviewed!
Number
Age (yrs)
ASA 3&4
Op’n Stay (d)
BO (d)
MorbidityMortality
Readmission
53 74 20 R&L colectomy
2 (2-60)
2 8%4%
15%
16 71 1 Sigmoid colectomy
2 (2-9)
2 6%nil
nil
31 69 14 rectopexy 3 2 nil3%
nil
29 55 reversal Hartmann’s
3 2 7%nil
7%
58 44 40 ASA 2+
R & L colectomy
43
3 7%nil
7%
14 / 11 64 / 68 Possum matched
R & L colectomy
3 v. 7 3
Summary of published data (to 2004)
Cochrane conclusions for practice
• Oral bowel prep
“… not been shown to be valuable
… may lead to ↑ anastomotic leakage
… oral bowel prep should be omitted”
Cochrane conclusions-implications for research
“results of this show the necessity of completing more, properly designed trails”
…blinding & stratification
…consider pre-op radiotherapy
…inclusion & exclusion criteria
…define discharge criteria, dropout & outcome measures
Proposed avoidance of oral prep…• Colon surgery
-R hemi / extended R hemi / subtotal-L hemi*
• Permanent stoma- Hartmann’s- APER*- PPC & ileostomy
• Proctology -Abdominal rectopexy* -Anal sphincter repair* -Rectal flap advancement*
• PPC & IPAA*
* Use enema
Proposed cases for oral prep?
• Generally need defunctioning- TME
• Undergone RT / CRT
• Possible need for on-table colonoscopy - the ‘unknown’ colonoscopist - severe sigmoid diverticular disease - small tumour - consider tattooing for laparoscopic resection
Dogma (n.) : - a doctrine or code of beliefs accepted as authorative-a doctrinal notion asserted without regard to evidence or truth
Recognise morbidity of bowel prep
Recognise limitations of current evidence base - effect of radiotherapy - type of procedures & pts suitable for accelerated care
Summary
