Purpose: Residents in obstetrics and gynecology are deemed to be proficient in transvaginal ultrasound (TVUS) upon graduation, although TVUS education in residency is not standardized.The objective of this study is to assess for improvement in TVUS knowledge among residents after viewing an educational DVD.Methods: This is a multisite prospective randomized controlled trial using an educational DVD ("Gynecology: Beginners Only"), compared to routine education. All participants completed a pretest on TVUS images and principles. The intervention group repeated the test after DVD viewing. During the trial, performing and logging TVUS examinations were encouraged. All enrolled residents repeated the test 6-10 months later.Results: Fifty-seven residents completed the study with a mean pretest score of 9.7 (1st year resident 9.8, 2nd year resident 9.6, 3rd year resident 10.1, 4th year resident 9.4, P = .763), with a mean of 31.5 TVUS examinations logged prior to intervention. The mean score in the intervention group (n = 34) improved significantly after viewing (11.2, P < 0.003). This improvement did not persist 6-10 months later on a follow-up quiz (mean 10.7, P = .894). At completion of the study, participants logged an average of 56.7 TVUS examinations.Conclusion: An educational DVD is easily implemented and demonstrates short-term benefit. Exploration of different teaching modalities in development of a comprehensive training program may improve long-term retention. K E Y W O R D S randomized controlled trial, resident education, transvaginal ultrasound 1 | INTRODUCTION Current practice in obstetrics and gynecology (OB/GYN) requires competent use of transvaginal ultrasound (TVUS), yet formal training during residency is typically limited and not standardized. The Accreditation Council for Graduate Medical Education (ACGME) reported in the September 2012 National Resident Report that graduating OB/GYN residents completed an average of 119.9 TVUS examinations as "surgeon" by the completion of their residency (range 0-623, 95th percentile was 260). 1 While the ACGME advises a resident to perform 50 TVUS examinations before completing residency, there are typically no specific program requirements, nor are there any specific recommendations in regards to how a program might assess competency in TVUS skills. Physicians who have graduated from an ACGME approved OB/GYN residency after 1982 are deemed competent to perform TVUS. Unfortunately, various components of TVUS use, including equipment calibration and transducer reprocessing, may not be part of the residency education. 2 Additionally, the American College of Radiology requires that for a practice to be accredited, the supervising physician must have at least 2 years of US experience during which at least 500 US examinations were performed or supervised and interpreted. 3 This is more than almost all OB/GYN residents perform during their 4-year residency.A PubMed search using the MeSH terms "ultrasonography," "internship and residency," and "gynecology" identified 1...