Comprehensive analysis of retrograde infection of a prophylactic pelvic drain in rectal cancer surgery: a retrospective cohort study

Purpose The role of prophylactic pelvic drains in rectal surgery remains controversial. A significant concern is the risk of retrograde drain infection, a type of surgical site infection occurring at the drain insertion site. To address the limited data on retrograde drain infection, we conducted an analysis to evaluate its features. Methods This retrospective cohort study analyzed 852 consecutive rectal cancer patients who underwent surgical resection with bowel anastomosis and prophylactic drain placement at a single referral hospital in Japan between January 2010 and December 2022. Retrograde drain infections were categorized as superficial/deep or organ/space, based on infection depth. Cases with anastomotic leakage (n = 10) were excluded from the analysis. Outcomes included the frequency, characteristics, risk factors, and oncological effects of retrograde drain infection. Results Retrograde drain infections occurred in 5.5% of the patients, mostly diagnosed on postoperative day seven or later. Methicillin-susceptible Staphylococcus aureus was the most frequent causative pathogen (32.6%). Male patients exhibited a higher infection rate than females (7.0% vs. 3.3%, P = 0.025). Infected patients experienced longer hospital stays (median 22 vs. 16 days, P < 0.001). Organ/space drain infections were associated with inferior recurrence-free survival in Stage I–III patients. Drain placement helped early detection in six of 10 cases of anastomotic leakage, with two patients avoiding stoma creation. Conclusion Retrograde drain infections are more common in male patients and prolong hospital stays. While prophylactic drains have benefits, such early detection of anastomotic leakage, their removal within seven days post-surgery is recommended to mitigate infection risks.