Introduction
Until now, mechanical bowel preparation (MBP) has been absolutely a dogma before colorectal surgery, as stated by Slim in 2004 [1]. However, MBP has been questioned during the last few years in many papers and especially in some meta-analysis published in the scientific literature. Some papers and reviews have stressed the uselessness of MBP. However, MBP is useful for cleaning the colon and removing firm faeces from the rectum both by oral laxative drugs, such as polyethyleneglycol, or by enema [ 2]. The advantage is easier management of viscus, and less possibility of outspreading faeces during surgery.
Moreover, cleaning makes it easier to perform a colonoscopy if necessary, while reducing the hazard of damaging the colonic wall during laparoscopic surgery [3]. Also, the hazard of sepsis is reduced if a dehiscence of anastomosis occurs.
Disadvantages of the procedure are patient dis- comfort, such as nausea, swelling, bloating, dehydra- tion and electrolyte disturbances, and a higher social cost for these drugs. Already more than 30 years ago a randomised trial questioned this issue [ 4], and dur- ing the last 10 years many trials and some meta- analysis has demonstrated the uselessness of MBP for prevention of septic complications and anastomosis dehiscence onset.
MBP and New Knowledge on Colonic Physiology
MBP is founded on three rules:
1. absolute starvation, especially of fibre;
2. antibiotic prophylaxis;
3. enemas and/or laxative drugs.
One of the last papers on this topic was by Platell and Hall [5], questioning MBP in “Colon and rectum disease” in 1998 [6]. Then many papers in the inter- national literature focused on this argument, espe- cially in the last three years [ 7–10]. All have stated that MBP is more harmful than useful.
The landmark was a deeper knowledge of the
physiology of the colon and its power in finding ener- gy for the body [ 10]. Really, the viscus is not only able to concentrate water and rescue sodium, but also produces energy for the whole body by producing short-chain fatty acids (SCFA) from the fermentation of food fibres.
The effects of SCFA are concentration dependent.
Low doses stimulate motility, while high doses inhib- it contractions of the loops [ 11]. Moreover, SCFA stimulate secretion of gastrointestinal peptides to modulate peristaltic waves [ 12]. SCFA increase microcirculation of the colon and distal ileum, where the large amount of anaerobes produce SCFA by fer- mentation [ 11]. SCFA are mainly produced in the colon and also stimulate mucosal blood flow in the rectum of patients who have undergone Hartmann’s procedure [ 11]. It must be kept in mind that micro- circulatory failure seems to be the main determining factor of anastomosis failure. After production by fermentation, SCFA are readily transported across colonic epithelium [ 11–13]. So, deprivation of fibre should be detrimental to colonic cells [ 12].
Fermentation by endogenous bacteria is really the second digestive system of our body. Really, man has two separate digestive systems, one based on diges- tion by enteric cells of the gut, and another much more complex one based on fermentation by diges- tion of bacteria. The bacteria are so important that we can call them the “microbe organ”. Energy [ 14] from fermentation produces SCFA and it is more than 8%
of the whole daily production of energy of the body.
SCFA are propionic, acetic and butyric acid.
Butyric acid is the real fuel of Bifidobacteria and is absorbed at 90% by the colonic cells. These agents could have a protective effect against leakage of anas- tomosis, enhancing vascularisation and protecting the anastomosis from leakage as failure of microcir- culation is caused by this complication [ 15].
Of extreme interest are the patterns of deprivation colitis found on colon segments without nutrients for many months, such as after dehiscence of colo- colonic anastomosis and performance of ileostomy [ 16]. The disease is caused by deprivation of nutri-
Mechanical Bowel Preparation (MBP) and Probiotic Administration Before Colorectal Surgery
Gerardo Mangiante, Annalisa Castelli, Birgit Feil
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G. Mangiante, A. Castelli, B. Feilents to the colonic mucosa [ 10]. So, we have to understand that nutrient delivery should be continu- ous to improve adequate blood supply and energy production to the mucosal cells [10].
On Burke et al.’s [17] evidence, MBP did not influ- ence the outcome in 2 groups of patients (with and without) submitted to ultra-low anterior rectal resec- tion. In 1998 Platell and Hall [5] performed a meta- analysis of this issue. MBP seems to reduce only wound infection onset. Jansen et al. [ 8] stated MBP could safely be omitted for right colonic resections, but not antibiotic drugs as prophylaxis of wound infection.
Van Geldere et al. [ 6] did not find any benefit with the use of MBP on colonic surgery in a trial of 185 patients. Zmora et al. [7] in 380 patients treated by colonic-rectal surgery, found that MBP has to be performed only in the presence of a small ( <3 cm) tumour that could not be seen on a perioperative colonscopy. Whilst Zmora and co-workers again, in a last specific review, found no data in support of MBP on colonic sugery [ 7].
Also, diet restriction is questionable as physiology has shown that faeces are made up of only 5–7%
food, while the majority is bacteria, apoptotic enteric cells and mucous. Mucous is the main part of the intestinal barrier and one of the most important weapons against bacterial translocation. It is made up of embedded immunologic cells from lamina pro- pria and mucosal lymphocytes. Therefore, it would be illogical to destroy it by aggressive oral prepara- tion or by enemas.
Slim et al. [ 1], late in 2004, suggested that MBP using polyethyleneglycol should be omitted before colorectal surgery. Anyway, the presence of hard fae- ces on left segments of the colon and rectum obstruct surgical procedures.
Kehlet [ 18] and Basse et al. [19] suggest perform- ing an enema as the surgeon prefers for cleaning the rectum and the colon before resection.
Ljungqvist [ 20] in 2005 gave up bowel preparation for colon resections, but still use it for rectal resec- tions. In their experience this procedure works fine, without any true benefit for laparoscopic resections for colon or rectum. For the former, this group have patients ready to leave the hospital 2–4 days after rec- tal surgery and 4–6 days after open surgery using small incisions as best possible. For a right-sided hemi-colectomy the incision is almost the same as in laparoscopic surgery.
Excessively strong enemas could destroy the mucus layer on the rectal and colonic mucosa, and this layer is full of IgA and probiotic bacteria.
Probiotic Agents on Colorectal Physiology
On nutrition, probiotics are nutritional supplements containing living micro-organisms, e.g., bacteria or yeasts, that have a beneficial impact on the host by improving the endogenous flora when introduced to a human being. And we can expect that prophylactic treatment such as MBP with these agents or a real antimicrobial interference therapy on surgical prac- tice.
Some series in surgical clinics, especially in liver transplantation, are encouraging [21]. In inflamma- tory bowel diseases such as ulcerative colitis after proctocolectomy, administration of probiotics avoids recurrence of pouchitis and shows excellent results in minimising the recurrence of this dismal complication [ 22].
Unfortunately, until now we have not known the true power of these agents, their safety, their power against other micro-organisms, their immunologic charge, etc. But in the future we are sure that probi- otics should be one of the most important strategies against the main threat of surgery, the onset of infec- tion.
Closing Remarks
The papers on this topic until now have been too few.
Danish experience [ 18] on fast track surgery report- ed sigmoid surgery more than rectal surgery. Howev- er, in rectal surgery many Authors have spoken out against aggressive preparation of the bowel, and the so-called fibre-free diet. Antibiotic prophylactic administration only aids in reducing wound infec- tion. Actually, the way forward is to reduce the strict rules of MBP, even if we have to obtain deeper infor- mation on this topic. Safeguarding the colonic envi- ronment could be the weapon to obtain the best result in this surgery.
References
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