Dr. Joseph Greene

Hien T. Nguyen, M.D., FACS, is an assistant professor of surgery at The Johns Hopkins University School of Medicine. After completing an undergraduate education at University of California, Davis, Dr. Nguyen earned his medical degree at University of California, Davis School of Medicine. He completed training in general surgery at University of California, San Francisco East Bay, followed by a fellowship in advanced laparoscopic and bariatric surgery at The Johns Hopkins University School of Medicine. Dr. Nguyen is an expert in single-incision surgery, robotic surgery and laparoscopic bariatric surgery (which includes Roux-en-Y gastric bypass, adjustable gastric bands, sleeve gastrectomy and duodenal switch). He was instrumental in helping to establish the single-incision approach for laparoscopic surgery at The Johns Hopkins Medical Institutions. Dr. Nguyen also specializes in the repair of complex hernias and abdominal wall reconstruction, utilizing minimally invasive and advance techniques. He also works with students and residents in surgical education and biomedical engineering. Dr. Nguyen currently is an active member of many academic organizations, including the American Society for Metabolic and Bariatric Surgery, the Society for Surgery of the Alimentary Tract, the Society of American Gastrointestinal and Endoscopic Surgeons, the American Hernia Society and the American College of Surgeons. His research interests include clinical outcomes in hernia surgery, critical care medicine, bariatric surgery and metabolic syndrome. Dr. Nguyen is rated as an Advanced provider by MediFind in the treatment of Umbilical Hernia. His top areas of expertise are Hernia, Umbilical Hernia, Obesity, Sleeve Gastrectomy, and Gastrectomy.

Masoud Rezvani is a Bariatric Medicine provider in Dulles, Virginia. Dr. Rezvani is rated as an Experienced provider by MediFind in the treatment of Umbilical Hernia. His top areas of expertise are Obesity, Gallbladder Disease, Gallstones, Gastrectomy, and Sleeve Gastrectomy.

Dr. Brett Parker is a general surgeon and fellowship-trained minimally invasive foregut and bariatric surgeon. He is an Assistant Professor of Surgery at Johns Hopkins and also the Program Director for the Johns Hopkins Advanced GI and Minimally Invasive Surgery Fellowship Program. Dr. Parker is an expert in minimally invasive surgical techniques including advanced laparoscopy and robotic surgery, as well as therapeutic flexible endoscopy. He is interested in promoting the evolving indications for surgical repair of hiatal hernias, as well as adjunct procedures surgeons can use to reduce recurrence rates. He offers a wide range of interventions for GERD, including innovative endoscopic therapies, and promotes early surgical referral to discuss and tailor therapy to individual patient circumstances. Dr. Parker also has a robust abdominal wall reconstruction and weight loss surgery practice. He is widely published on the surgical outcomes of foregut surgery, emerging technologies, and innovation, as well as surgical simulation and skills transfer. Dr. Parker has consistently been selected as a Washingtonian Magazine Top Doctor in 2023, 2024, and 2025. As a member of the Johns Hopkins Division of Minimally Invasive Surgery in the Greater Washington Area, Dr. Parker is dedicated to the best, individualized, patient outcomes. Learn more about Dr. Parker and his partners within the Johns Hopkins Division of Minimally Invasive Surgery, the Johns Hopkins Heartburn Center and the Johns Hopkins Motility and Neurogastroenterology Center. Dr. Parker is rated as an Advanced provider by MediFind in the treatment of Umbilical Hernia. His top areas of expertise are Hiatal Hernia, Hernia, Congenital Diaphragmatic Hernia, Endoscopy, and Gallbladder Removal.