This study aims to examine the prevalence and bacteriological findings of different types of intrauterine fluid collection in women presenting with postmenopausal bleeding and the risk factors for predicting positive microbiological culture, mixed growth, and anaerobic growth. This is a retrospective cohort study. Data from all of the women who were assessed in our one-stop postmenopausal bleeding clinic between 2008 and 2011 and who were found to have intrauterine fluid collection were reviewed. Endometrial aspirates of all women were sent for bacterial culture and histological examination. The risk factors for positive culture were assessed by both univariate and multivariate analyses. A total of 228 cases of intrauterine fluid collection were included for analysis. There were 109 (47.8%) cases of pyometra, 98 (43.0%) cases of hydrometra, and 21 (9.2%) cases of hematometra. Escherichia coli, Bacteroides fragilis, and Enterococcus were the commonest microorganisms isolated from endometrial aspirates. Both endometrial malignancy and benign intrauterine pathologies are not risk factors for positive culture. Advanced age (>75 y) is an independent risk factor for positive culture (odds ratio, 2.89; 95% CI, 1.39-6.01) and mixed growth (odds ratio, 2.18; 95% CI, 1.02-4.67). Residency in nursing homes is an independent risk factor for mixed growth (odds ratio, 2.61; 95% CI, 1.21-5.63) and anaerobic growth (odds ratio, 2.55; 95% CI, 1.01-6.44). E. coli, B. fragilis, and Enterococcus are the commonest microorganisms isolated from intrauterine fluid. Apart from drainage of the intrauterine fluid collection, successful management also requires appropriate antibiotics and improvement in perineal hygiene.