Preparation in Colorectal Surgery: Impact on SSIs and Enhanced Recovery Protocols

Fig. 8.1

Graphic representation of practice patterns throughout the United States with regard to mechanical bowel preparation demonstrating that 24% of surgeons omit a mechanical bowel prep, 29% use MBP with oral antibiotics, and 45% use MBP in the absence of oral antibiotics. (Data from Refs. [1–3])

Efficacy of Mechanical Bowel Preparation (MBP) in Colorectal Surgery

The efficacy of the MBP combined with OAs for elective intestinal surgery was first demonstrated in the 1970s when the Nichols-Condon bowel preparation (typically a clear liquid diet for 24 hours followed by neomycin and erythromycin in addition to vigorous mechanical cleansing) was described [4–6]. This demonstrated a reduction in SSI following colorectal surgery from 43% to 9%. Following this sentinel publication, the Nichols-Condon bowel preparation became the gold standard for the following two decades with widespread, global use and adoption of this “aggressive” cathartic prep, which was often poorly tolerated by patients [7, 8]. However, the modern use of the MBP has been called into question due to a number of secular trends in surgery including patient satisfaction/tolerance, concern of overall renal failure with hyperosmotic preparations, the development of broader spectrum parenteral (IV) antibiotics, and finally the advent of enhanced recovery programs (ERPs). As a result, there has been a proliferation of research into the efficacy of the MBP (with or without OAs), which continues to this day (Fig. 8.2).

../images/465809_1_En_8_Chapter/465809_1_En_8_Fig2_HTML.jpg — Fig. 8.2

Graphic representation of the number of published manuscripts within PubMed per year on the use of mechanical preparation prior to surgery

With the development of parenteral third-generation cephalosporins and other parenteral antibiotics, many of the MBP trials conducted in the early 2000s omitted OAs based on the assumption that IV antibiotics would mitigate the need for OAs [9, 10]. This was in stark contrast to the initial trials conducted during the 1970s. It subsequently became evident that a MBP in the absence of OAs results in liquid, bacteria-laden stool that is more likely to contaminate the operative field than formed stool in the unprepped colon [11, 12]. Due to the omission of OAs in a majority of these studies, clinical trials and meta-analyses from the early 2000s failed to demonstrate efficacy in SSI or anastomotic leak prevention with MBP [9, 10, 13–15]. In fact, the 2005 Cochrane meta-analysis suggested that, compared to no prep at all, MBP alone may result in a higher rate of anastomotic leakage and surgical site infection [14]. Thus, the omission of the MBP became standard practice and one of the primary tenets of the early ERP movement [16]. Many ERP protocols to this day still recommend omission of mechanical bowel preparations altogether. Please refer to the chapters on ERPs in colorectal surgery for more details regarding specific protocols (Chaps. 7 and 8).

In a Cochrane Collaboration meta-analysis published in 2009, Nelson and coauthors demonstrated the importance of OAs in the presence of prophylactic IV antibiotics and a MBP. Their review of 182 RCTs found that OAs administered in the presence of a MBP in addition to IV antibiotics for prophylaxis were associated with a 75% reduction in the rate of SSI [17]. This subsequently led to the publication of several studies evaluating the efficacy of OA combined with the MBP. Multiple large risk-adjusted national database studies including the National Surgical Quality Improvement Program (NSQIP) and the Michigan Surgical Quality Collaborative-Colectomy Best Practices Project demonstrated significant reduction in infectious morbidity (SSI and anastomotic leak) associated with the use of a MBP when combined with oral antibiotics [1, 18–25]. Furthermore, the addition of OAs does not seem to increase the risk of Clostridium difficile infection and may, in fact, reduce the risk through the prevention of SSI and subsequent need for broad-spectrum antibiotics [26]. The recommendation for the use of a MBP in the presence of OAs is now supported by multiple meta-analyses [27].

Taken together, these data demonstrate that a MBP alone in the absence of OAs cannot be recommended. However, based on several prospective randomized controlled trials (RCTs) and databases studies totaling over 100,000 patients, a combination of a MBP and nonabsorbable OAs is associated with the lowest rate of infectious morbidity following elective colorectal surgery. This distinction in the use of MBP with and without OAs is critical when interpreting available literature to optimize surgical outcomes [1, 2, 20, 28].

There are emerging data suggesting that OAs may be beneficial at reducing SSI in elective colorectal surgery in the absence of MBP, at least relative to regimens without OAs [29, 30]. Several recent large NSQIP studies have examined the role of OA prep without MBP. Atkinson and coauthors [31] conducted a study of just over 6000 patients, demonstrating that OA alone, without MBP, was associated with a reduction in SSI rates from 13.7% to 9.7% (p = 0.01). Klinger and coauthors [23] examined roughly 30,000 colectomy patients within NSQIP and found that while a combined MBP with OAs was superior, OA alone was favorable to omission of MBP in terms of SSIs. A significant limitation of this study was that only 6% (1374) of the cohort received OA alone, suggesting significant selection bias.

Finally, Garfinkle and coauthors [30] in a similar study with over 40,000 colectomies found that OA alone and combined OA + MBP resulted in an equivalently low rate of SSI, leak, and ileus, suggesting that the combined prep offered no advantage over OAs alone. These studies have been included in a recent networked meta-analysis whose findings were that overall combined MBP + OAs produced the lowest rate of infectious complications with OAs alone as the next best option for obtaining the lowest rate of SSIs [21]. There are no RCTs examining OAs alone compared to other strategies. Therefore, whether or not isolated OAs in the absence of a mechanical preparation is truly effective in reducing infectious morbidity remains to be seen.

To assess current practice regarding current bowel prep use, the authors conducted a Twitter® poll, of mostly academic surgeons, from around the globe. This included 141 votes from a variety of different countries and showed that a combined MBP and OA prep is now the most commonly used preparation (59%), while 21% of surgeons omit use of any MBP. A similar contemporaneous poll regarding sigmoid colectomies showed similar results with the addition that some surgeons prescribe enemas for left-sided procedures (Fig. 8.3).

../images/465809_1_En_8_Chapter/465809_1_En_8_Fig3_HTML.jpg — Fig. 8.3

Results of recent Twitter (Twitter Inc., San Francisco, CA, USA) poll on the use of bowel preparations by academic surgeons

Bowel Preparations and Laparoscopic Colorectal Surgery

Aside from the salutary effect of MBPs on SSIs, the MBP offers a practical and technical benefit specific to intestinal surgery through decompression of the bowel. This allows for easier manipulation of the colon, particularly with laparoscopy. In addition, a mechanical preparation is obviously preferable should an intraoperative colonoscopy become necessary (e.g., unable to locate the lesion intraoperatively) which could force the decision to abandon surgery or perform an extended resection with hopes of resecting the lesion. Thus, many colorectal surgeons who perform mostly laparoscopic surgery, including the authors of this chapter and their respective partners, prefer a combined preparation for these reasons.

Types of Mechanical Bowel Preparations

One common misconception held by many perioperative care providers is that all MBPs cause dehydration, electrolyte imbalance, and detrimental physiologic effects. Although many of the early hyperosmotic phosphate-based solutions did lead to dehydration, the isosmotic solutions in most current MBP regimens are better tolerated. Table 8.1 describes the clinical characteristics of various MBP regimens.

Table 8.1

Various mechanical bowel preparations and their properties

Name	Properties
Polyethylene glycol (PEG, GoLYTELY® [Braintree Laboratories, Braintree, MA, USA], Colyte® [Pendopharm, Montreal, Canada])	Safe, large volume, poor taste
Sulfate-free PEG (NuLytely® [Braintree Laboratories, Braintree, MA, USA], TriLyte® [Schwarz Pharma, Milwaukee, WI, USA])	Safe, large volume, better taste
Low-volume PEG and bisacodyl (HalfLytely® [Braintree Laboratories, Braintree, MA, USA])	Safe, lower volume (2 L)
Low-volume sulfate solution (SUPREP® [Braintree Laboratories, Braintree, MA, USA])	Low volume, risk of electrolyte abnormalities and renal dysfunction
Ascorbic acid lavage (MoviPrep® [Salix Pharmaceuticals, Bridgewater, NJ, USA])	Safe, better taste, caution in patients with G6PD deficiency
Sodium phosphate Liquid form Visicol® tablets (Salix Pharmaceuticals, Bridgewater, NJ, USA) OsmoPrep® tablets (Salix Pharmaceuticals, Bridgewater, NJ, USA)	Low volume, electrolyte and fluid shifts, caution in cardiac/liver/renal dysfunction; elderly/dehydrated, those taking angiotensin-converting enzyme inhibitors or angiotensin receptor blockers
Magnesium citrate as adjunct to PEG	Lower volume, caution in renal dysfunction