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Providers
At True Care Surgery Center
Dr. Andrea Tieng
Dr. Andrea Tieng was born and raised in New York City. She graduated Summa Cum Laude from the City University of New York and earned her medical degree from the State University of New York Health Science Center at SUNY Downstate College of Medicine in Brooklyn, New York.
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She completed her internship and residency in Internal Medicine at the Albert Einstein College of Medicine at Long Island Jewish Medical Center in New Hyde Park, New York, where she also completed her Gastroenterology and Hepatology Fellowship.
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Dr. Tieng is licensed to practice medicine in both California and New York. She is a member of the American College of Gastroenterology and the American Gastroenterology Association.
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Before founding her own practice in Rancho Cucamonga, Dr. Tieng worked as a private gastroenterologist at Cedars-Sinai Medical Center in Los Angeles.
Dr. M. Bader Hammami
Dr. M. Bader Hammami is a gastroenterologist specializing in inflammatory bowel disease (IBD). He has extensive experience managing IBD in pregnancy and treating patients with complex Crohn's disease and ulcerative colitis. He also holds a special clinical interest in immune-mediated colitis and enteritis, particularly those related to checkpoint inhibitor therapies.
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Dr. Hammami's research has focused on reproductive health and drug safety in men with IBD, IBD management in the elderly, improving quality of care, and optimizing preventive care strategies for IBD patients.
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He earned his medical degree from the University of Damascus, Faculty of Medicine, and completed his Internal Medicine residency and Gastroenterology fellowship at Saint Louis University, where he also served as president of the Saint Louis University Residency Association. He went on to complete a specialized IBD fellowship at the University of California, San Francisco.
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