Program Leadership
Our program leadership includes diverse backgrounds and specialties, ensuring a broad experience and teaching base for our residents.
John J Byrne, MD MPH
Assistant Professor, Residency Program Director
byrnej@uthscsa.edu | 210-567-5009
Dr. Byrne received his Bachelor of Science in Education from Baylor University in 2006. Prior to attending medical school, he received a M.P.H. from the University of Texas School of Public Health in 2009. He then completed medical school at the Joe R. & Teresa Lozano Long School of Medicine at University of Texas Health Science Center in San Antonio in 2013. He completed his residency in Obstetrics and Gynecology at the University of Chicago Medical Center in Chicago, IL, before coming back to Texas to complete a fellowship in Maternal-Fetal Medicine at the University of Texas Southwestern Medical Center/Parkland Hospital in 2020. Dr. Byrne joined the faculty at the University of Texas Health Science Center at San Antonio as an Assistant Professor in the Division of Maternal-Fetal Medicine. His current interests include multifetal gestation, maternal cardiac disease, and prenatal diagnosis.
Morgan Fisler, MD
Assistant Professor/Clinical, Associate Program Director
Dr. Fisler received a Bachelor of Science in Biology from Trinity University in San Antonio in 2013. She then attended the University of Texas Medical Branch in Galveston where she received her Medical Degree in 2017 with a distinction in Global Health. She was awarded membership to the Alpha Omega Alpha Honor Society. Dr. Fisler completed residency in Obstetrics and Gynecology at the Medical University of South Carolina in 2021. She joined our faculty following her residency training. She is passionate about general obstetrics and gynecology, minimally invasive surgery, and medical education.
Sarah Villarreal, MD
Associate Professor/Clinical, Associate Program Director
Dr. Villarreal (she/her/hers) is an Associate Professor in the department of Obstetrics and Gynecology. Dr. Villarreal received her Bachelor of Science in Biomedical Engineering from Cornell University where she also did research on biomedical implants. She subsequently did a year-long research fellowship with the National Institutes of Health (NIH) as a member of their NIH Academy, doing research in healthcare disparities and inequities and how this affects health outcomes. She returned to Texas after this fellowship to do further research at the University of Texas at Austin. She then received her medical degree from Baylor College of Medicine where she completed the Ethics Track as well as the Care for the Underserved Track. She completed her residency in Obstetrics and Gynecology at University of Colorado in Denver, Colorado.
Dr. Villarreal’s clinical interests include gynecologic surgery, pediatric and adolescent gynecology, family planning and contraception, and in sexual health. She has a special interest in promoting access to health care in underserved south Texas populations. Her practice strives on including her patients as a member of their own care team, and empowering women to make educated decisions about their own body and health.
Dr. Villarreal is also a LGBQT+ ally and is now seeing adult patients for gender affirming therapy, menstrual suppression, and pelvic pain management.
Dr. Villarreal is originally from Corpus Christi. She enjoys reading, hiking and being outside with her family.
Contact us
For questions about the residency program, contact:
Jackie Barrera
GME Program Coordinator-Senior
Phone: 210-567-4953
Fax: 210-567-3485
Email: barrerajd@uthscsa.edu