The Natural Course of Peri graft Fluid Collections After Kidney Transplantation: A Serial Imaging Cohort Study.

Background. Fluid collections are common after kidney transplantation, but their prevalence at scheduled imaging and their management are inconsistent from canter to canter. We describe the cross sectional prevalence and management of perigraft collections, including an exploratory deepdrain subgroup. Methods. In this retrospective single center cohort, 146 consecutive adult kidney transplant recipients (Cleveland Clinic Weston Hospital, July 2024 to June 2025) were imaged on postoperative day 0/1 and at approximately 1 and 3 months. Routine deep drainage was avoided (n=124), 22 clinically selected recipients with perioperative anticoagulation received a deep drain. The primary outcome was cross sectional prevalence of a perigraft collection at each visit. Secondary outcomes were management among patients with a collection. Drain group comparisons were exploratory. Results. Collections were present in 29 of 146 recipients at postoperative day 0/1 (19.9%; 95% CI, 14.2 to 27.1), 71 of 146 at 1 month (48.6%; 95% CI, 40.7 to 56.7), and 34 of 146 at 3 months (23.3%; 95% CI, 17.2 to 30.8). Prevalence in the no drain group was 21.0%, 50.0%, and 23.4%, respectively; corresponding prevalence in the deep drain group was 13.6%, 40.9%, and 22.7%. Between group prevalence comparisons were not statistically significant at any time point. BMI was higher in the deep-drain group than in the no-drain group (30.04 vs 27.1 kg/m2; P=0.01). Among patients with a 1-month collection, management did not differ significantly between groups (any invasive management, 11.1% vs 16.1%; P=1.00). Among patients with a 3month collection, invasive management was more common in the deep drain group than in the no drain group (80.0% vs 13.8%; P=0.007). This comparison included only five deep-drain recipients and was confounded by clinical selection, perioperative anticoagulation, and BMI imbalance. Conclusions. Perigraft collection prevalence was highest at 1 month and lower at 3 months in this predominantly no drain cohort. Most collections were managed conservatively, and invasive treatment was uncommon in the no-drain group. The deep drain subgroup provides clinically relevant information about high risk recipients selected for drainage but cannot support causal conclusions regarding drain benefit or harm. Patient level linkage is required to distinguish persistence, resolution, and new collection formation.