Study Objective: To analyze what factors influence a provider's decision to order a pelvic ultrasound (PUS) in the emergency department (ED) for adolescents with abnormal uterine bleeding (AUB), to determine if endometrial stripe (EMS) measurements are used in treatment decisions, and to evaluate if treatment outcomes differ based on EMS thicknesses. Methods: Retrospective chart review of patients aged 11-19 presenting to the ED with AUB from 2006 to 2018. Those receiving a PUS were divided into three EMS groups: >= 5 mm, 6-9 mm, and <= 10 mm. Outcomes were evaluated in admitted patients by progress notes indicating resolution of bleeding. Cross-tab, chi(2), and logistic and linear regression analysis were performed. Results: Of 258 adolescents meeting study criteria, 113 (43.8%) had a PUS. None had an abnormality. A PUS was more likely to be performed in patients with lower hemoglobin values ( P < .003). Provider decision to order a PUS did not differ by age or bleeding duration ( P > .1). Among those with a PUS, 67 (59%) received hormonal therapy (pill, progestin-only, IV estrogen). There were no significant differences in treatment choices based on EMS ( P < .061) or, among the 44 admitted patients (17%), in the time it took bleeding to stop after initiating treatment (pill: P = .227, progestin-only: P = .211, IV estrogen: P = .229). Conclusion: In adolescents with AUB in the ED, performing a PUS was more common in those with low hemoglobin. EMS thickness did not appear to affect treatment decisions or inpatient outcomes. Larger studies are needed to confirm the current findings and determine if PUS is needed in the evaluation of AUB.