Objective A comparison of different routes for the administration of clodronate disodium liposomes to determine the most effective method of rat endometrial macrophage clearance.Methods Female 8-week-old SD rats were randomly divided into a unilateral control group(injected with 100 μL PBS liposomes into the left uterine cavity),unilateral clearance group(injected with 100 μL clodronate liposomes into the right uterine cavity),bilateral control group(injected with 100 μL PBS liposomes into the bilateral intrauterine),bilateral clearance group(injected with 100 μL clodronate liposomes into the bilateral intrauterine),whole-body control group(injected with 500 μL PBS liposomes into the caudal vein),and whole-body clearance group(injected with 500 μL clodronate liposomes into the caudal vein).Hematoxylin and eosin staining was used to observe the morphology and structures of uterine and ovarian tissues,immunohistochemistry was used to observe the presence of macrophages in uterine and ovarian tissues,and flow cytometry was used to detect changes to macrophage cell counts in uterine and ovarian tissues.Results There were no significant differences in the structures or morphology of the uterus and ovary among the groups.Immunohistochemical staining showed that,compared to the control group,the unilateral and bilateral uterine clearance groups'population of terine macrophages was significantly decreased(P＜0.001),but there was no difference in the accumulation of macrophages in the ovary(P＞0.05).The number of macrophages in both uterine and ovarian tissues decreased in the whole-body clearance group(P＜0.01,P＜0.01).Compared with the unilateral and bilateral clearance groups,the whole-body clearance group had more macrophages in the ovarian tissues(P＜0.05).Flow cytometry showed that,compared with the control group,each clearance group's percentages of macrophages in the uterine tissue were significantly reduced(P＜0.001,P＜0.001,P＜0.05).Compared to the whole-body clearance group,the unilateral and bilateral clearance groups'endometrial macrophages had superior clearance activity(P＜0.05,P＜0.05).In addition,the number of macrophages in ovarian tissue decreased in all clearance groups compared to the control group.The decrease in macrophage number was most pronounced in the whole-body clearance group(P＜0.05),and there was no significant difference in numbers between the unilateral and bilateral clearance groups and the control group(P＞0.05).Conclusions Local injection of clodronate liposomes was more effective than caudal injection for clearing uterine macrophages,and the impact on ovarian macrophages was largely avoided.Thus local clodronate liposome injection is an improved method for establishing a local uterine macrophage clearance model.