Current & Recent Gastroenterology Fellows

Learn more about current and recent University of Maryland/NIH Clinical Scholars Gastroenterology Fellowship Program fellows below. You can also view a list of recent Gastroenterology Fellow Publications to learn more about research project findings.

Current Fellows

Alla Turshudzhyan
Alla Turshudzhyan, D.O.
Clinical Fellow

Chief Residency Year: University of Connecticut

Residency: University of Connecticut

Medical School: University of New England

Year in Program: 3rd Year

Research Projects: I have strong interest in gastrointestinal disease with a particular focus on esophageal disease. I am especially interested in esophageal motility disorders, gastroesophageal reflex disease, Barrett’s esophagus, lymphocytic esophagitis, esophageal malignancies, and surveillance/therapy options. My areas of interest and research also include gastrointestinal and hepatic manifestations of inborn errors of immunity, APECED, and DEGOS disease. Another area of focus is post-HSCT gastrointestinal bleeding and exploring esophageal string test as the diagnostic tool for the detection of Helicobacter pylori and antimicrobial resistance genes.

Xixi Xu
Xixi Xu, M.D.
Clinical Fellow

Residency: Boston University School of Medicine

Medical School: Boston University School of Medicine

Year in Program: 3rd Year

Research Projects: My research centers on how immune dysregulation and inherited genetic instability shape gastrointestinal and hepatic disease, with the goal of improving risk stratification, surveillance, and targeted therapies for high risk patients. I investigate the manifestations and mechanisms of non cirrhotic portal hypertension in patients with autoinflammatory diseases and bone marrow failure syndromes, aiming to understand why a subset of these patients develop severe portal hypertension in the absence of cirrhosis and how we can identify them earlier. I am also studying the risk and natural history of esophageal cancer in individuals with Fanconi anemia, an exceptionally high risk population, to inform evidence based screening strategies and cancer prevention approaches. In parallel, I examine the clinical presentation and phenotypic characteristics of Common Variable Immunodeficiency (CVID) enteropathy, working to better define this heterogeneous condition and to link specific clinical patterns with underlying immune defects and treatment responses. Finally, I am focused on unraveling the genetic and immune profiles of patients with refractory inflammatory bowel disease who do not respond to JAK inhibitors, with the broader objective of understanding resistance pathways and paving the way for more precise, mechanism based therapies. Together, these projects reflect my interest in improving outcomes for patients with rare, complex, and often under recognized diseases.

Asif Hitawala, M.B.B.S.
Asif Hitawala, M.B.B.S.
Clinical Fellow

Residency Year: Cleveland Clinic Foundation/Fairview Hospital

Medical School: Ravindra Nath Tagore Medical College in India

Year in Program: 2nd Year

Carolina Versaille, M.D.
Carolina Versaille, M.D.
Clinical Fellow

Residency Year: Mount Sinai Beth Israel

Medical School: St. George's University School of Medicine Grenada

Year in Program: 2nd Year

Alumni Testimonials

My fellowship at the NIH was truly extraordinary. With outstanding mentorship from dedicated faculty, I gained invaluable expertise navigating rare and complex conditions. The program’s robust research opportunities ignited my curiosity and honed my skills, ensuring I stepped into practice with confidence and precision. I’m forever grateful for an experience that so thoroughly prepared me for a fulfilling career in gastroenterology.

~Bryan Curtin, M.D, M.H.Sc.

Post Fellowship Training: NIH-Duke Master’s Program in Clinical Research Neurogastroenterology and Motility Advanced Fellowship – Augusta University Digestive Health Center, Augusta, GA
Current Position: Director, The Center for Neurogastroenterology and GI Motility, Mercy Medical Center

A fellowship at the NIH is very unique in that it balances a strong focus on clinical and endoscopic skills with a vast array of research opportunities. As a fellow, I had the opportunity to manage patients with various rare pathologies and to collaborate closely with other clinical specialties. Moreover, I was able to get involved with a number of research projects early on, which led to poster presentations and publications. However, the best part of being at the NIH, were the people. I was surrounded by a great group of co-fellows, as well as brilliant and supportive attendings, who made my training not just successful, but also incredibly enjoyable and fun.

~Anna Strongin, M.D.

Current Position: Practicing Gastroenterologist, Capital Digestive Care, MD

Fellowship through the UMMS/NIH Clinical scholars program set me up for success as an academic transplant hepatologist. The combination of robust clinical exposure both in large academic hospitals and the unique clinical training environment of NIH offered a well-rounded experience to gain expertise in the clinical management of common gastrointestinal and hepatic disorders, and the scientific evaluation of complex and rare diseases. Mentors at NIH helped solidify the fundamentals of clinical research which furthered my interest in academic medicine positioning me well beyond fellowship. I am grateful to the faculty and for the training experience!

~David M. H. Chascsa, M.D.

Post Fellowship Training: Transplant Hepatology Advanced Fellowship - Mayo Clinic, Scottsdale, AZ
Current Position: Assistant Professor of Medicine; Program Director- Transplant Hepatology, Mayo Clinic, Scottsdale, AZ

Recent Fellows

Bilal Khalid, M.D.
Clinical Fellow

Post Fellowship Training: Transplant Hepatology Fellowship – Mayo Clinic

Current Position: Assistant Professor of Medicine, Johns Hopkins University

Hanna Blaney, M.D., M.P.H.
Clinical Fellow

Post Fellowship Training: Hepatology Transplant Fellowship – Georgetown University

Current Position: Assistant Professor of Medicine, Virginia Commonwealth University

Anusha Vittal, M.D.
Clinical Fellow

Current Position: Acting Gastroenterologist - MedStar Health

Walter Lai, M.D., Ph.D.
Clinical Fellow

Current Position: Acting Gastroenterologist - Meritus Health

Bilal Asif, M.D.
Clinical Fellow

Post Fellowship Training: Hepatology Transplant Fellowship – Mayo Clinic

Current Position: Clinical Assistant Professor, NYU Grossman Long Island School of Medicine

Alex Yang, M.D.
Clinical Fellow

Post Fellowship Training: Hepatology Transplant Fellowship - Massachusetts General Hospital

Current Position: Assistant Professor of Medicine, University of California, San Diego

Monica Passi, M.D.
Clinical Fellow

Post Fellowship Training: Advanced Endoscopy Fellowship –North Shore University/Long Island Jewish Medical Center (Northwell Health)
Current Position: Acting Gastroenterologist, Gastro Center of Maryland

Sumona Bhattacharya, M.D.
Clinical Fellow

Post Fellowship Training: Advanced Inflammatory Bowel Disease Fellowship – NYU Grossman School of Medicine
Current Position: Assistant Professor of Medicine, George Washington University Medical Faculty Associates

Ben Da, M.D.
Clinical Fellow

Post Fellowship Training: Transplant Hepatology Advanced Fellowship – Icahn School of Medicine at Mount Sinai
Current Position: Senior Associate Director Clinical Development. Gilead Sciences, Inc

Natasha Kamal, M.D.
Clinical Fellow

Post Fellowship Training: Inflammatory Bowel Disease Fellowship – University of Maryland

Current Position: Acting Gastroenterologist, Frederick Gastroenterology Associates

Bryan Curtin, M.D., M.H.Sc.
Clinical Fellow

Post Fellowship Training: NIH-Duke Master’s Program in Clinical Research

Post Fellowship Training: Neurogastroenterology and Motility Advanced Fellowship – Augusta University Digestive Health Center, Augusta, GA

Current Position: Director, The Center for Neurogastroenterology and GI Motility, Mercy Medical Center

Ehsan Chitsaz, M.D., M.H.Sc.
Clinical Fellow

Current Position: Acting Gastroenterologist, TriHealth

Sonia Taneja Sharma, M.D.
Clinical Fellow

Current Position: Assistant Professor of Clinical Medicine, Keck School of Medicine of USC

Samuel Schueler, M.D.
Clinical Fellow

Current Position: Assistant Professor of Medicine, George Washington University Medical Faculty Associates; Program Director - George Washington University GI Fellowship Program

Hawwa Alao, M.D.
Clinical Fellow

Post Fellowship Training: Interventional Gastroenterology Fellowship - Harbor UCLA Medical Center
Current Position: Practicing Gastroenterologist, Swedish Health Services

Anna Strongin, M.D.
Clinical Fellow

Current Position: Practicing Gastroenterologist, Capital Digestive Care, MD

David M. H. Chascsa, M.D.
Clinical Fellow

Post Fellowship Training: Transplant Hepatology Advanced Fellowship - Mayo Clinic, Scottsdale, AZ
Current Position: Assistant Professor of Medicine, Program Director - Transplant Hepatology, Mayo Clinic (Scottsdale)

Derek M. Tang, M.D.
Clinical Fellow

Current Position: Practicing Gastroenterologist, Kaiser Foundation Hospital - Orange County, Anaheim, CA

Nancy Ho, M.D
Clinical Fellow

Current Position: Practicing Gastroenterologist, Sutter Health- California Pacific Medical Center, San Francisco, CA

Jim Y. Chou, M.D.
Clinical Fellow

Current Position: Practicing Gastroenterologist, United Gastroenterologists, Orange County CA

Mark T. Voellinger, M.D.
Clinical Fellow

Current Position: Practicing Gastroenterologist, Wheeling Hospital

Thomas Simcox, M.D.
Clinical Fellow

Current Position: Practicing Gastroenterologist, Anne Arundel Gastroenterology

Preet Bagi, M.D.
Clinical Fellow

Post Fellowship Training: Inflammatory Bowel Disease Advanced Fellowship - University of California, San Diego Inflammatory Bowel Disease Center

Current Position: Saddleback Medical Group, Laguna Hills, CA

Current Position: Clinical Director, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health

Sajneet Khangura, M.D.
Clinical Fellow

Current Position: Practicing Gastroenterologist, Gastroenterology Consultants of San Antonio

Apurva Trivedi, M.D.
Clinical Fellow

Current Position: Practicing Gastroenterologist, Texas Digestive Disease Consultants

Manish Arora, M.B.B.S.
Clinical Fellow

Current Position: Practicing Gastroenterologist, Decatur, AL

Doug Weinstein, M.D.
Clinical Fellow

Current Position: Director, Advanced Gastrointestinal (GI) Motility Program, CapitalHealth Medical Center- Pennington, NJ

Apurva Modi, M.D.
Clinical Fellow

Post Fellowship Training: Transplant Hepatology Advanced Fellowship- University of Maryland
Current Position: Transplant Hepatologist, Baylor All Saints Medical Center, Fort Worth, TX

Erik von Rosenvinge, M.D.
Clinical Fellow

Current Positions: Professor of Medicine, University of Maryland School of Medicine; Vice Chair, Department of Medicine; Director, Medical Care Clinical Center, VA Maryland Health Care System

Michael D. Yao, M.D.
Clinical Fellow

Current Positions: Chief, Gastroenterology and Hepatology Section. Washington DC VA Medical Center. Associate Professor of Medicine, George Washington University.

Last Reviewed April 2026