Colorectal surgery and preoperative bowel preparation: aren't we drawing hasty conclusions?

Mechanical and oral antibiotic bowel preparation versus no bowel preparation in right and left colectomy: subgroup analysis of MOBILE trial

BACKGROUND

In retrospective series, mechanical and oral antibiotic bowel preparation (MOABP) has been reported to reduce surgical-site infections (SSIs) after colectomy compared with no bowel preparation (NBP).

METHOD

This was a subgroup analysis of a multicentre randomized trial that included patients scheduled for elective colectomy. The MOABP group underwent mechanical bowel preparation, and took 2 g neomycin and 2 g metronidazole orally during the day before surgery. The NBP group did not undergo bowel preparation. Patients were categorized according to the side of resection (right versus left colectomy), and these subgroups compared for postoperative outcomes.

RESULTS

Among 217 patients undergoing right colectomy (106 in MOABP and 111 in NBP group), SSI was detected in seven (7 per cent) and 10 (9 per cent) patients (odds ratio (OR) 0.71, 95 per cent c.i. 0.26 to 1.95; P = 0.510), anastomotic dehiscence in two (2 per cent) and two (2 per cent) patients (OR 1.05, 0.15 to 7.58; P = 1.000), and the mean(s.d.) Comprehensive Complication Index (CCI) score was 9.4(12.9) and 10.5(18.0) (mean difference -1.09; 95 per cent c.i. -5.29 to 3.11; P = 0.608) in the MOABP and NBP groups respectively. Among 164 patients undergoing left colectomy (84 in MOABP and 80 in NBP group), SSI was detected in five (6 per cent) and eight (10 per cent) patients (OR 0.57, 0.18 to 1.82; P = 0.338), anastomotic dehiscence in four (5 per cent) and five (6 per cent) patients (OR 0.75, 0.19 to 2.90; P = 0.742), and the CCI score was 10.2(13.1) and 6.5(11.0) (mean difference 3.68, -0.06 to 7.42; P = 0.053) in the MOABP and NBP groups respectively.

CONCLUSIONS

MOABP did not decrease the rate of SSI or complications in patients undergoing either right or left colectomy compared with NBP.

Reducing anastomotic leak in colorectal surgery: The old dogmas and the new challenges

Anastomotic leak (AL) constitutes a significant issue in colorectal surgery, and its incidence has remained stable over the last years. The use of intra-abdominal drain or the use of mechanical bowel preparation alone have been proven to be useless in preventing AL and should be abandoned. The role or oral antibiotics preparation regimens should be clarified and compared to other routes of administration, such as the intravenous route or enema. In parallel, preoperative antibiotherapy should aim at targeting collagenase-inducing pathogens, as identified by the microbiome analysis. AL can be further reduced by fluorescence angiography, which leads to significant intraoperative changes in surgical strategies. Implementation of fluorescence angiography should be encouraged. Progress made in AL comprehension and prevention might probably allow reducing the rate of diverting stoma and conduct to a revision of its indications.

Mechanical and oral antibiotic bowel preparation versus no bowel preparation for elective colectomy (MOBILE): a multicentre, randomised, parallel, single-blinded trial

BACKGROUND

Decreased surgical site infections (SSIs) and morbidity have been reported with mechanical and oral antibiotic bowel preparation (MOABP) compared with no bowel preparation (NBP) in colonic surgery. Several societies have recommended routine use of MOABP in patients undergoing colon resection on the basis of these data. Our aim was to investigate this recommendation in a prospective randomised context.

METHODS

In this multicentre, parallel, single-blinded trial, patients undergoing colon resection were randomly assigned (1:1) to either MOABP or NBP in four hospitals in Finland, using a web-based randomisation technique. Randomly varying block sizes (four, six, and eight) were used for randomisation, and stratification was done according to centre. The recruiters, treating physicians, operating surgeons, data collectors, and analysts were masked to the allocated treatment. Key exclusion criteria were need for emergency surgery; bowel obstruction; colonoscopy planned during surgery; allergy to polyethylene glycol, neomycin, or metronidazole; and age younger than 18 years or older than 95 years. Study nurses opened numbered opaque envelopes containing the patient allocated group, and instructed the patients according to the allocation group to either prepare the bowel, or not prepare the bowel. Patients allocated to MOABP prepared their bowel by drinking 2 L of polyethylene glycol and 1 L of clear fluid before 6 pm on the day before surgery and took 2 g of neomycin orally at 7 pm and 2 g of metronidazole orally at 11 pm the day before surgery. The primary outcome was SSI within 30 days after surgery, analysed in the modified intention-to-treat population (all patients who were randomly allocated to and underwent elective colon resection with an anastomosis) along with safety analyses. The trial is registered with ClinicalTrials.gov, NCT02652637, and EudraCT, 2015-004559-38, and is closed to new participants.

FINDINGS

Between March 17, 2016, and Aug 20, 2018, 738 patients were assessed for eligibility. Of the 417 patients who were randomised (209 to MOABP and 208 to NBP), 13 in the MOABP group and eight in the NBP were excluded before undergoing colonic resection; therefore, the modified intention-to-treat analysis included 396 patients (196 for MOABP and 200 for NBP). SSI was detected in 13 (7%) of 196 patients randomised to MOABP, and in 21 (11%) of 200 patients randomised to NBP (odds ratio 1·65, 95% CI 0·80-3·40; p=0·17). Anastomotic dehiscence was reported in 7 (4%) of 196 patients in the MOABP group and in 8 (4%) of 200 in the NBP group, and reoperations were necessary in 16 (8%) of 196 compared with 13 (7%) of 200 patients. Two patients died in the NBP group and none in the MOABP group within 30 days.

INTERPRETATION

MOABP does not reduce SSIs or the overall morbidity of colon surgery compared with NBP. We therefore propose that the current recommendations of using MOABP for colectomies to reduce SSIs or morbidity should be reconsidered.

FUNDING

Vatsatautien Tutkimussäätiö Foundation, Mary and Georg Ehrnrooth's Foundation, and Helsinki University Hospital research funds.