Effect of preoperative anemia on postoperative outcomes in mixed hemorrhoids: a retrospective observational study

BACKGROUND: Anemia is a common complication of long-term hematochezia in patients with mixed hemorrhoids. This study aimed to evaluate the effect of preoperative anemia on the prognosis of mixed hemorrhoids after Milligan-Morgan hemorrhoidectomy. METHODS: A total of 127 patients with mixed hemorrhoids who underwent Milligan-Morgan hemorrhoidectomy at the Affiliated Hospital of Southwest Medical University from January 2021 to August 2022 participated in this study, comprising 48 patients in the preoperative anemia group and 79 patients in the preoperative non-anemia group. Postoperative complications such as postoperative pain, delayed bleeding, wound infection, wound edema, urinary retention, insomnia severity index (ISI) within 7 days, wound healing time, and recurrence rates (prolapse or bleeding) within 12 months were retrospectively analyzed in the two groups. RESULTS: There were no significant differences in the demographic and baseline clinical characteristics between the two groups (P > 0.05). The visual analog scale pain scores at 12 h (P = 0.018), 1 day (P = 0.010), 3 days (P = 0.034), and 7 days (P = 0.001) after surgery and total analgesic consumption within 7 days (P = 0.036) in the preoperative anemia group were higher than those in the preoperative non-anemia group. The ISI within 7 days in the preoperative anemia group was higher than that in the preoperative non-anemia group (P = 0.046). There were no significant differences in delayed bleeding, wound infection, wound edema (P = 0.740), urinary retention (P = 0.648), anal stenosis, or wound healing time (P = 1.101) between the two groups. There were no significant differences in recurrence (prolapse or bleeding) rates within 12 months between the two groups (P = 0.513). CONCLUSIONS: In this retrospective observational study, preoperative anemia was associated with higher postoperative pain scores and poorer sleep quality within 7 days after Milligan-Morgan hemorrhoidectomy. However, no significant associations were observed between preoperative anemia and other postoperative complications, wound healing time, or 12-month recurrence rates. Given the observational design and the exploratory nature of the analysis, these findings should be interpreted with caution and require confirmation in larger, adequately powered studies with multivariable adjustment.