Mechanical Bowel Preparation for Elective Colorectal Surgery: Is it Enough?

Dear editor, We recently read with great interest the article of Dr. Peppas and colleagues and strongly favour their approach and concerns about the mechanical bowel preparation of colorectal patients (MBP). In order to give our contribution to the discussion, we would like to focus on some issues that still need to be answered about this timehonoured procedure. To date, 12 randomised controlled trials (RCT) are present in the literature including 4,919 patients (2,463 in the MBP group and 2,456 in the non-MBP group). The overall analysis of the main outcome measures shows that no parameter reaches the statistical significance between MBP vs. non-MBP patients (Table 1).The only exception is represented by the occurrence of cardiac events (acute myocardial infarctions, atrial fibrillations, heart failures, angina pectoris) that seem decreased in the non-MBP group (Table 1). The reasons for this influence could lie in the well-known effects of MBP on body fluids (dehydration) and electrolytes (marked imbalances) that, along with others cardiovascular risk factors (age, comorbid conditions, neoadjuvant treatments, surgical stress and intraoperative blood losses), could further increase the perioperative risk. Taken together, results available confirm the lack of an objective advantage on the use of MBP in elective patients and, in particular cases, would suggest some potential harmful effects. However, different biases need to be pointed out. Important differences in the protocols adopted render difficult the combination of results in a metanalytic approach. Almost all studies adopted an adequate antibiotic prophylaxis for both groups (MBP vs. non-MBP patients), but in four of them this information was not specified and, when described, different prophylactic regimens were adopted: in three studies, ceftriaxone and metronidazole were used, in one cephalothin and metronidazole, in one gentamicin and metronidazole, in two neomycin and erythromycin, in one sulfamethoxazole–trimethoprim and metronidazole for 46% of patients, cephalosporin and metronidazole for 33% of patients and doxycycline with metronidazole for 14% of patients. Additionally, the mechanical preparation regimen was also different: seven trials adopted the regimen of oral polyethylene electrolyte glycol solution as mechanical bowel preparation, one the sodium phosphate, two both and two did not specify it. The heterogeneity of RCTs involved also the recruitment of patients (one study was conducted on children) and the results presented, including the treatment effect and the precision of its estimate (Fig. 1). When screened with validated quality measures (i.e. the Jadad scale), no RCT scored more than 2 meaning that results presented could be J Gastrointest Surg (2009) 13:1392–1394 DOI 10.1007/s11605-008-0556-1