Mechanical bowel preparation (MBP) and antibiotics (oral and/or intravenous) have historically been used to decrease infectious complications in surgeries that involve manipulation of bowel or potential risk of injury. The use of MBP has recently been challenged in the colorectal surgery literature, thus inspiring similar critical evaluation of our practices in urology. This review gives a brief overview of the history of mechanical and oral antibiotic bowel preparation, as well as the evolution of the practice trends in colorectal surgery and urology. We also examine contemporary guidelines in skin preparation as well as antimicrobial prophylaxis before surgery.
Key points
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Evidence would suggest that mechanical bowel preparation can be safely omitted in cystectomy with ileal urinary diversion.
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Use of oral antibiotic bowel preparation in urology has not been well studied, although colorectal literature shows that it is associated with decreased rate of infective complications.
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Intravenous antibiotic prophylaxis should be given within 1 hour before incision and discontinued 24 hours after termination of surgery unless patient has risk factors.
Introduction
Historically, preoperative mechanical bowel preparation (MBP) has been considered the standard of care in patients undergoing colorectal and urologic surgeries involving bowel. In recent years, the routine preoperative MBP has been questioned, with a shift away from use in both colorectal and urology literature. In this review, we examine the evidence behind MBP, antimicrobial prophylaxis (AMP), and skin preparation for open and laparoscopic urologic surgeries.
Introduction
Historically, preoperative mechanical bowel preparation (MBP) has been considered the standard of care in patients undergoing colorectal and urologic surgeries involving bowel. In recent years, the routine preoperative MBP has been questioned, with a shift away from use in both colorectal and urology literature. In this review, we examine the evidence behind MBP, antimicrobial prophylaxis (AMP), and skin preparation for open and laparoscopic urologic surgeries.
Mechanical bowel preparation
Rationale
The main concerns of a surgeon performing bowel anastomosis include infectious complications, bowel leak, and anastomotic dehiscence. Additionally, quick recovery of bowel function and reduction of the hospital length of stay are other important goals. These objectives spurred many historical prophylaxis regimens, which continue to a large extent today. Ironically, recent evidence would suggest that these practices may not serve these goals.
Mechanical cleansing of the bowel was thought to be associated with a lower complication rate by decreasing intestinal microflora; however, even early studies reported that MBP did not reduce the concentration of intestinal microflora in the ileum, colon, and stool. In fact, a more contemporary study showed that patients who received MBP actually have more bacteria at the anastomosis compared with those who did not received MBP.
Another perception is that MBP decreases intestinal contents, thereby limiting spillage into the peritoneal cavity at the time of bowel resection, thus potentially decreasing infective complication rates; however, evidence would suggest the contrary. A prospective trial of MBP versus none in 333 patients undergoing colorectal surgery showed a higher spillage rate in patients with liquid bowel contents, which was associated with MBP. Although this study demonstrated a trend toward higher surgical and overall complication rates when spillage occurred, this did not achieve statistical significance.
Last, concerns with regard to anastomotic leak and wound infections have been extensively reviewed in colorectal literature. A recent Cochrane review of 18 trials evaluating a role of MBP in elective colorectal surgery demonstrated that there was no difference between anastomotic leakage or wound infection when MBP is compared with none or compared with rectal enema alone. In a more recent review by the Agency for Healthcare Research and Quality of 60 studies, there was no difference in all-cause mortality, anastomotic leakage, wound infection, and peritonitis for patients undergoing elective colorectal surgery.
Types of Mechanical Bowel Preparation
MBP has evolved since first popularized by Nichols and colleagues in the early 1970s. The Nichols-Condon preparation has been used for colorectal surgery and often adopted by urologists. Freiha also described a mechanical and antibiotic preparation regimen for urologic surgery in 1977 ( Table 1 ). Since then, different agents and regimens have emerged. Current literature of MBP agents primarily come from gastroenterology exploring the efficacy of various regimens in the setting of colonoscopy. Contemporary practices are usually less extensive than those of the Nichols-Condon or Freiha regimens. The different types of MBP are reviewed in Table 2 .
| Author | Regimen |
|---|---|
| Nichols et al, 1972 |
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| Freiha, 1977 |
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| Agent | Dosage and Precautions |
|---|---|
| Polyethylene glycol-3350 (PEG) electrolyte solution (GoLYTELY and NuLYTELY: Braintree Laboratories, Braintree, MA) |
|
| PEG alone |
|
| Magnesium citrate |
|
| Oral sodium phosphate solution |
|
Oral Antibiotics in Combination with Mechanical Bowel Preparation
Although the routine administration of parenteral antibiotics is recommended in nearly all patients, the use of oral antibiotics has largely fallen out of favor. Similar to the use of MBP, the practice of using oral antimicrobials to decrease intraluminal bacterial load has decreased over time, from 87% to 92% routine use in colorectal surgery in the 1990s to 36% in a 2010 survey. However, there is recent renewed interest in evaluating the effect of oral antibiotic use. Using oral antibiotics to decrease intraluminal microbial burden began in 1940 and was popularized in the early 1970s by Nichols and colleagues. They showed that use of oral neomycin and erythromycin (see Table 1 ) in combination with MBP decreased bacterial concentration from intraluminal aspirates of ileum, cecum, and transverse colon, and was superior in MBP alone in preventing wound infections.
More recently, a large retrospective analysis in 9940 patients found that the use of oral antibiotics, with or without MBP, was associated with 67% decrease in surgical site infection (SSI) in colorectal surgeries. The reduction of SSI maintained even if MBP was not performed. Similarly, a prospective, multi-institution study demonstrated that patients undergoing colorectal surgery and receiving oral antibiotics with MBP are less likely to have SSI (4.5% vs 11.8%), organ space infection (1.8% vs 4.2%), and superficial SSI (2.6% vs 7.6%) when compared with MBP alone. They also had lower rate of prolonged ileus of 3.9% versus 8.6%, and a similar rate of Clostridium difficile infection. Meta-analysis of randomized controlled trials showed that nonabsorbable oral antibiotic in addition to an intravenous antibiotic versus intravenous antibiotic alone had reduced risk of wound infections with relative risk of 0.57. No difference was seen between the groups with regard to risk of anastomotic leak or intra-abdominal abscess. The 1999 Centers for Disease Control and Prevention guidelines for prevention of SSIs continue to advocate for nonabsorbable oral antimicrobials administered in divided doses the day before colorectal surgeries.
There is a paucity of studies evaluating the effect of the use of oral antibiotic bowel preparation for urologic surgeries. The use of oral antibiotics has traditionally been advocated for urinary diversion using bowel segment, although the use of oral antibiotics has been eliminated in various contemporary series evaluating MBP in cystectomy and urinary diversion. These oral antibiotic regimens are described in Table 3 .
| Antibiotic | Regimen |
|---|---|
| Kanamycin |
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| Neomycin + erythromycin base |
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| Neomycin + metronidazole |
|
Disadvantages of Mechanical and Antibiotic Bowel Preparation
Although the complications associated with MBP and/or oral antibiotic ingestion are low, risks are acceptable if offset against perceived benefit. Urologic operations that incorporate bowel are usually operations associated with increased operative duration, or in patients with more risk factors. For instance, radical cystectomies with urinary diversion are often performed in patients older than 70 years with extensive smoking history, and as such have other respiratory or cardiovascular comorbidities. Additionally, bladder augmentations are performed in patients with neurogenic bladders who often have other comorbidities also, including hypoalbuminemia. Therefore, if MBP and/or oral antibiotic ingestion offers no distinct advantage, then 1 to 2 days of fasting or clear fluids, diarrhea, and potential for dehydration would be best avoided.
MBP adverse effects are largely associated with electrolyte disturbances, which would be normally tolerated except in those with renal dysfunction, or the elderly. There also have been case reports of electrolyte abnormalities and seizures with use of sodium picosulfates/magnesium citrate for bowel preparation in patients without history of seizures. Histologic studies have revealed loss of superficial mucus with epithelial cells, as well as inflammatory changes within the bowel wall in patients undergoing MBP.
The use of oral antibiotics to alter intestinal flora raises the question of whether patients are placed at higher risk for C difficile infection. Retrospective case-controlled study of patients receiving elective colon surgery who underwent MBP showed that the rate of C difficile infection within 30 days was 7.4% in those who received oral antibiotics versus 2.6% in those who did not receive oral antibiotics. However, several recent studies have shown no increased rate of C difficile infection in those who received oral antibiotics (1.3% vs 1.8%), but there also is no increased rate in those who received MBP versus those who did not.
Bowel Preparation in Urology
Although colorectal surgery experience can guide practices, urologic surgery may have different requirements; most commonly small bowel is used, which has different microbiota from large bowel. Bacterial density increases in the distal small bowel (duodenum 10 1 –10 3 colony-forming units [CFU]/mL, jejunum/ileum 10 4 –10 7 CFU/mL), but it is still at markedly lower concentration than large bowel contents of 10 6 –10 12 CFU/mL. Furthermore, bowel segments are typically incorporated into the urinary tract, exposing sterile environments to bowel contents.
Cystectomy with urinary diversion
Routine MBP before cystectomy and urinary diversion has recently been challenged and the evidence would suggest that MBP confers no distinct advantage. Although the reference urologic textbook Campbell-Walsh Urology 2012 recommends 4 L polyethylene glycol 3350 and electrolytes starting noon the day before surgery, along with intravenous hydration and oral antibiotic preparation when using intestinal segments for urinary diversion, many studies have concluded that there is no difference between mortality, infection rate, and bowel leakage rate. In fact, a meta-analysis of 2 randomized controlled trials and 5 cohort studies looking at the impact of MBP on cystectomy with ileal urinary diversion showed no difference between MBP versus none with regard to bowel leak, obstruction, or mortality rate. One retrospective review showed that there was increased length of stay and higher incidence of prolonged ileus in the MBP group. Furthermore, in patients undergoing MBP in combination with oral antibiotics, there is a higher frequency of mucosal edema and submucosal congestion on histopathological examination of ileum, and ironically a higher rate of bacterial overgrowth of Escherichia coli . Although there are no American guidelines on the use of bowel preparation, European Association of Urology guidelines suggested that preoperative bowel preparation is not mandatory before radical cystectomy.
Enhanced recovery protocols
Recent emergence of enhanced recovery after surgery (ERAS) protocols for radical cystectomy and urinary diversion, which eliminate MBP and oral antibiotic preparation, have further corroborated evidence in support of abandoning MBP. In fact, evidence from these studies would suggest that MBP is possibly doing more harm than good. For example, in a retrospective series published by Daneshmand and colleagues, excellent perioperative, infective, and readmission rate outcomes were demonstrated in 110 patients receiving ERAS without MBP. When compared with a historical group of matched patients, a significantly shorter hospital stay of 4 versus 8 days was observed in the ERAS group. Similarly, another ERAS study that eliminated the use of sodium picosulfate MBP in cystectomy with patients receiving ileal urinary diversion demonstrated no differences in morbidity or mortality between groups, and again significantly reduced hospital stay in those receiving ERAS without MBP. In 2013, a systematic review of the literature of current ERAS after radical cystectomy did not demonstrate any improvement in outcomes with MBP.
Enterocystoplasty
The role of MBP in patients undergoing enterocystoplasty, who commonly have concomitant neurogenic bowel, has not been well studied. A study in children with myelomeningocele and constipation showed that 39% of children in the study have small intestinal bacterial overgrowth confirmed by H 2 /CH 4 lactulose breath tests. The increased bacterial load in small bowel in this population can potentially expose the augmented urinary tract to different bacterial concentration when compared with patients without neurogenic bowel or constipation undergoing the same surgery. Despite that, case series in the pediatric literature shows no difference in outcomes between children who underwent cystoplasty using ileum with preoperative MBP versus those who did not undergo MBP. A retrospective review of 162 children undergoing enterocystoplasty without preoperative MBP, where colonic segments were used in more than 85% of the patients, showed no increased rate of complications. Expert opinion in the field continues to be divided and questions whether or not omission of MBP can be adopted widely to those with constipation or neurogenic bowel, where large fecal bolus distal to the anastomotic site might become a source of obstruction. Suggestions have been made to consider abdominal radiography to determine if there is large fecal bolus distal to the future anastomotic site to prompt use of preoperative MBP.
Radical prostatectomy
Because of the intimate anatomic relationship between the prostate and rectum, intraoperative rectal injury can occur, at a rate of 0% to 8.2% for open prostatectomy and 0.8% to 1.2% in robotic-assisted laparoscopic prostatectomy (RALP). MBP traditionally has been used to decrease potential complications, such as infections and fistula formation, in the event of rectal injury and to avoid the need for diverting colostomy in a primary repair. Older literature advocates diverting colostomy in the event of rectal injury in unprepared bowel given reports of higher complication rate after primary repair in patients who did not undergo MBP. Now, some investigators advocate the use of diverting colostomy only for those with massive fecal spillage, previous radiotherapy, or a tense suture line. Whether there is a need for full MBP versus modified protocols continues to be debated, especially in the modern era of RALP, which now accounts for the overwhelming majority of radical prostatectomies carried out currently in the United States. In the senior author’s (RBN) experience, during RALP, minor rectal injuries recognized intraoperatively can safely be repaired robotically, without the need for tissue interposition or diverting colostomy. However, experience of all of these to date occurred in patients who received MBP, and moving away from this practice is difficult without a high level of evidence to persuade otherwise. Published data are nearly exclusively in open surgery, where other investigators describe successful primary repair of rectal injuries without MBP, but using omentum as interposition flap. Another retrospective review of an open radical prostatectomy cohort in Japan demonstrated that, in those who sustained rectal injuries, there was no difference in outcomes between the MBP group and non-MBP group with regard to infectious complication, delayed colostomy rate, length of stay, or total cost. Most contemporary series reviewing the outcomes of repair of intraoperative rectal injury still include preoperative MBP. The investigators in several studies noted that they have trended away from MBP, although they continue to advocate the use of MBP in select patients with high-grade disease and suggested that MBP should be considered for those with history of previous transurethral resection of the prostate or radiotherapy. Evidence would suggest that many urologists find it difficult to move away from indoctrinated practices too. In a recent survey of US urologists, 35% of those who performed open prostatectomy use MBP, whereas 19% use enema alone; 55% of urologists who perform laparoscopic and/or RALP used MBP for these surgeries, whereas 16% use enema alone (Chi AC, McGuire BB, Nadler RB: Bowel preparation in urologic surgery: practice pattern amongst urologists, 2015. Submitted manuscript). For both open prostatectomy and RALP, many experts still recommend clear liquid diet and magnesium citrate on day before surgery, with an enema on the morning of surgery.
Laparoscopic and robotic surgery
Little has been published assessing the need of MBP in laparoscopic surgeries. The Society of American Gastrointestinal and Endoscopic Surgeons guidelines recommended the use of MBP, recognizing the lack of evidence, before laparoscopic resection of curable colon and rectal cancer, to facilitate bowel manipulation and possibility for intraoperative endoscopy. Expert opinion in urology agrees that although no MBP is necessary for laparoscopic and robotic operations that are extraperitoneal or retroperitoneal, MBP might be helpful to improve visualization and working space. For transperitoneal procedures not using bowel segments, a light MBP, such as clear liquid diet, Dulcolax suppository, or half dose of magnesium citrate can be used. Surgeries in which entry into the bowel lumen is anticipated, or if dense intra-abdominal adhesions are likely to be encountered, a full MBP is suggested. However, more recent studies suggest that MBP in surgeries not involving bowel can be omitted. A retrospective study in Japan showed that for patients undergoing laparoscopic nephrectomy for T1-T3 tumor, the use of MBP did not affect operating room time, length of stay, or overall complications. Another study, randomizing 308 patients undergoing laparoscopic gynecologic surgery to MBP versus none showed that although intraoperative surgical view and bowel handling was statistically better in the MBP group, the small difference was not clinically important. In a survey conducted among adult urologists practicing in the United States, there is a wide range of frequency of MBP use across various urologic surgeries, shown in Fig. 1 (Chi AC, McGuire BB, Nadler RB: Bowel preparation in urologic surgery: practice pattern amongst urologists, 2015. Submitted manuscript).
