Large bowel preparation may cause a substantial change in the gut microbiota and metabolites. Here, we included a bowel prep group and a no-procedure control group and evaluated the effects of bowel prep on the stability of the gut microbiome and metabolome as well as on recovery. Gut microbiota and metabolome compositions were analyzed by 16S rRNA sequencing and capillary electrophoresis time-of-flight mass spectrometry, respectively. Analysis of coefficients at the genus and species level and weighted UniFrac distance showed that, compared with controls, microbiota composition was significantly reduced immediately after the prep but not at 14 days after it. For the gut metabolome profiles, correlation coefficients between before and immediately after the prep were significantly lower than those between before and 14 days after prep and were not significantly different compared with those for between-subject differences. Thirty-two metabolites were significantly changed before and immediately after the prep, but these metabolites recovered within 14 days. In conclusion, bowel preparation has a profound effect on the gut microbiome and metabolome, but the overall composition recovers to baseline within 14 days. To properly conduct studies of the human gut microbiome and metabolome, fecal sampling should be avoided immediately after bowel prep.

AIMTo verify the validity of the endoscopy guidelines for patients taking warfarin or direct oral anticoagulants (DOAC).METHODSWe collected data from 218 patients receiving oral anticoagulants (73 DOAC users, 145 warfarin users) and 218 patients not receiving any antithrombotics (age- and sex-matched controls) who underwent polypectomy. (1) We evaluated post-polypectomy bleeding (PPB) risk in patients receiving warfarin or DOAC compared with controls; (2) we assessed the risks of PPB and thromboembolism between three AC management methods: Discontinuing AC with heparin bridge (HPB) (endoscopy guideline recommendation), continuing AC, and discontinuing AC without HPB.RESULTSPPB rate was significantly higher in warfarin users and DOAC users compared with controls (13.7% and 13.7% vs 0.9%, P < 0.001), but was not significantly different between rivaroxaban (13.2%), dabigatran (11.1%), and apixaban (13.3%) users. Two thromboembolic events occurred in warfarin users, but none in DOAC users. Compared with the continuing anticoagulant group, the discontinuing anticoagulant with HPB group (guideline recommendation) had a higher PPB rate (10.8% vs 19.6%, P = 0.087). These findings were significantly evident in warfarin but not DOAC users. One thrombotic event occurred in the discontinuing anticoagulant with HPB group and the discontinuing anticoagulant without HPB group; none occurred in the continuing anticoagulant group.CONCLUSIONPPB risk was similar between patients taking warfarin and DOAC. Thromboembolism was observed in warfarin users only. The guideline recommendations for HPB should be re-considered.

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Background: It remains unclear whether type of antiplatelet (AP) therapy, AP combination therapy, and AP continuing or switching strategy affect the risk of postpolypectomy bleeding (PPB). In this study, we sought to elucidate this risk. Methods:We analyzed 1050 patients who underwent colonoscopic polypectomy: 525 AP users and 525 controls matched for age, sex, comorbidities, concomitant non-steroidal anti-inflammatory drugs use, and polyp characteristics who did not receive antithrombotics. PPB risk was evaluated by AP number, type, and continuing or switching strategies during the peri-endoscopic period. Results:In multivariate analysis, bleeding risk increased significantly as the number of AP agents used increased (monotherapy, adjusted odds ratio [aOR], 3.7; dual antiplatelet therapy (DAPT), 4.6; triple antiplatelet therapy (TAPT), 11.1) compared with controls.With monotherapy, significantly increased PPB risk was found for aspirin (aOR, 4.3), thienopyridine (aOR, 6.3), and cilostazol (aOR, 5.9), but not for eicosapentaenoic acid or other APs (beraprost, limaprost, sarpogrelate, dilazep, or dipyridamole). With DAPT, significantly increased PPB risk was found for combination aspirin plus cilostazol, but not aspirin plus other APs. Bleeding rates for continuing monotherapy were 4.3% for aspirin and 0% for thienopyridine, cilostazol, and other APs, respectively.Conclusions: Analysis of this large polypectomy dataset showed that the use of low-dose aspirin, thienopyridine, or cilostazol and a combination of these is associated with increased PPB risk. Although PPB risk was high with DAPT or TAPT, PPB rate in any antiplatelet monotherapy even with a continuing strategy was low at < 5%.