2016 Update on minimally invasive gynecologic surgery

Can mechanical bowel prep positively affect outcomes in gynecologic laparoscopy, or should it be discarded?

Arnold A, Aitchison LP, Abbott J. Preoperative mechanical bowel preparation for abdominal, laparoscopic, and vaginal surgery: a systematic review. J Minim Invasive Gynecol. 2015;22(5):737−752.

Popularized for more than 4 decades, the practice of presurgical bowel preparation is predicated on the notion that the presence of less, versus more, feces can minimize bacterial count and thereby reduce peritoneal contamination. Logically then, surgical site infections (SSIs) should be reduced with bowel preparation. Moreover, the surgical view and bowel handling during laparoscopic surgery should be improved, with surgical times consequently reduced.

Surgeons must weigh the putative benefits of mechanical bowel preparation against the unpleasant experience it causes for patients, as well as the risks of dehydration or electrolyte disturbance it may cause. To this day, a considerable percentage of gynecologists and colorectal surgeons routinely prep the bowel after weighing all of these factors, despite the paucity of evidence for the practice's efficacy to reduce SSI and improve surgical outcomes.⁷

The results of this recent systematic review critically question the usefulness of preoperative bowel preparation for abdominal, laparoscopic, and vaginal surgery.

Details of the analysis
The authors evaluated high-quality studies on mechanical bowel preparation to assess evidence for:

• surgeon outcomes, including the surgical field and bowel handling
• operative outcomes, including intraoperative complications and operative times
• patient outcomes, including postoperative complications, overall morbidity, and length of stay.

The authors identified RCTs and prospective or retrospective cohort studies in various surgical specialties comparing preoperative bowel preparation to no such prep. Forty-three studies met inclusion criteria: 38 compared prep to no prep, and 5 compared prep to a single rectal enema. Five high-grade studies in gynecology were included (n = 795), with 4 of them RCTs of gynecologic laparoscopy (n = 645).

Operative field and duration
Of the studies comparing bowel prep with no prep, only the 5 gynecologic ones assessed operative field. Surgical view was perceived as improved in only 1 study. In another, surgeons only could guess allocation half the time.

Sixteen studies evaluated impact of mechanical bowel preparation on duration of surgery: 1 high-quality study found a significant reduction in OR time with bowel prep, and 1 moderate-quality study found longer operative time with bowel prep.

Patient outcomes
Of all studies assessing patient outcomes, 3 high-quality studies of colorectal patients (n = 490) found increased complications from prep versus no prep, including anastomotic dehiscence (P = .05), abdominal complications (P = .028), and infectious complications (P = .05).

Length of stay was assessed in 26 studies, with 4 reporting longer hospital stay with bowel prep and the remaining finding no difference between prep and no prep.

Across all specialties, only 2 studies reported improved outcomes with mechanical bowel preparation. One was a high-quality study reporting reduced 30-day morbidity (P = .018) and infectious complication rates (P = .018), and the other was a moderate-quality study that found reduced SSI (P = .0001) and organ space infection (P = .024) in patients undergoing bowel prep.

Mechanical bowel preparation vs enema
Bowel prep was compared with a single rectal enema in 5 studies. In 2 of these, patient outcomes were worse with enema. One high-quality study of 294 patients reported increased intra-abdominal fecal soiling (P = .008) in the enema group. (The surgeons believed that bowel preparation was more likely to be inadequate in this group, 25% compared with 6%, P<.05.) Whereas there was no statistical difference in the incidence of anastomotic leak between these groups, there was higher reoperation rate in the enema-only group where leakage was diagnosed (6 [4.1%] vs 0, respectively; P = .013).

Bowel prep and preoperative and postoperative symptoms
Six high-quality studies reported on the impact of mechanical bowel preparation on patient symptoms, such as nausea, weakness, abdominal distention, and satisfaction before and after surgery. In all but 1 study patients had significantly greater discomfort with bowel preparation. In 2 of the 6 studies, patients had more diarrhea (P = .0003), a delay in the first bowel movement (P = .001), and a slower return to normal diet (P = .004).

What this EVIDENCE means for practice
The theory behind mechanical bowel preparation is not supported by the evidence. Despite the fact that the bowel is not customarily entered, up to 50% of gynecologic surgeons employ bowel preparation, with the hope of improving visualization and decreasing risk of an anastomotic leak. The colorectal studies in this review demonstrate no evidence for decreased anastomotic leak or infectious complications. By extrapolation, there is no evidence that using preoperative bowel prep bestows any benefit if bowel injury occurs inadvertently and if resection or reanastomosis is then required.

Among the 7 studies examining bowel prep in laparoscopy (4 gynecology, 3 urology, and 1 colorectal), only data from 1 demonstrated an improved surgical field (and in this case only by 1 out of 10 on a Likert scale). The impact of mechanical bowel preparation on the visual field is the same for diagnostic or complex laparoscopic surgeries. One high-quality study with deep endometriosis resection demonstrated no change in the operative field as reflected by no practical differences in OR time or complications.

Preparing the bowel for surgery is an intrusive process that reduces patient satisfaction by inducing weakness, abdominal distention, nausea, vomiting, hunger, and thirst. Whereas this systematic analysis failed to confirm any benefit of the process, it provides evidence for the potential for harm. Mechanical bowel preparation should be discarded as a routine preoperative treatment for patients undergoing minimally invasive gynecologic surgery.