https://www.selleckchem.com/products/piperacillin.html .au/Trial/Registration/TrialReview.aspx?id=370473&isReview=true. Australian New Zealand Clinical Trials Registry ACTRN12616001036404; https//www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=370473&isReview=true. Rates of postoperative Crohn's disease recurrence remain high, although the ability to predict this risk of recurrence remains limited. As such, we aimed to determine the association of histologic features at the time of resection with postoperative recurrence. Electronic databases were searched through February 2020 for studies that reported risk of clinical, endoscopic, or surgical postoperative recurrence in patients with positive resection margins, plexitis, or granulomas in the index specimen. Pooled risk ratios (RRs) with 95% CIs were calculated for this risk in patients with and without these histologic features. Twenty-one studies (2481 patients) assessed positive resection margins, 10 studies (808 patients) assessed plexitis, and 19 studies (1777 patients) assessed granulomas. Positive resection margins increased the risk of clinical (RR, 1.26; 95% CI, 1.06-1.49; I = 41%) and surgical (RR, 1.87; 95% CI, 1.14-3.08; I = 71%) recurrence, with a trend toward endoscopic recurrence (RR, 1.56; 95% CI, 0.79-3.05; I = 85%). Granulomas increased the risk of clinical (RR, 1.31; 95% CI, 1.05-1.64; I = 36%) and endoscopic (RR, 1.37; 95% CI, 1.00-1.87; I = 49%) recurrence, with a trend toward surgical recurrence (RR, 1.58; 95% CI, 0.89-2.80; I = 75%). Plexitis increased the risk of endoscopic recurrence (RR, 1.31; 95% CI, 1.00-1.72; I = 20%), with a trend toward clinical recurrence (RR, 1.34; 95% CI, 0.95-1.91; I = 46%). Positive resection margins, granulomas, and plexitis are predictive of postoperative Crohn's disease recurrence and should be recorded at the time of index resection. Positive resection margins, granulomas, and plexitis are predictive of postoperative Crohn's disease recurrence and sh