Meet Our Staff
The physicians of Digestive Disease Associates, P.A. (DDA) are a highly qualified group of gastroenterologists dedicated to providing the most up-to-date treatment in a patient-centered environment. Together, they combine their individual expertise and special interests to offer their patients comprehensive, state-of-the art gastrointestinal care.
Our physicians are on staff at several quality area hospitals, which include St. Agnes Hospital, Howard County General Hospital, and Union Memorial Hospital. DDA physicians hold various leadership roles throughout these respective medical communities.
All of our physicians are board-certified and remain active in both national and local professional associations. Many of them hold leadership positions in these organizations. They are all family-oriented professionals who live and raise families in the local communities in which they serve.
Thomas W. Abernathy Jr, M.D., joined Digestive Disease Associates (DDA) in 2008. He graduated with honors from Morehouse College in Atlanta, GA, where he received a Bachelor of Science degree in Biology. Dr. Abernathy continued his studies in Philadelphia at the Medical College of Pennsylvania & Hahnemann University School of Medicine (now Drexel University School of Medicine) where he received his medical degree. Dr. Abernathy returned to the Washington, D.C. metropolitan area and attended the Washington Hospital Center in the District of Columbia where he completed his Internal Medicine Residency Program and his fellowship in Gastroenterology and Hepatology. In August of 2005, he joined a private practice in Annapolis, MD. After 2 years, he decided to embark on new opportunities at DDA.
Dr. Abernathy is board certified in gastroenterology and a diplomate of the American Board of Internal Medicine. He's also a member of the American Gastroenterology Association, the American Society of Gastrointestinal Endoscopy, the American College of Gastroenterology, the American Association for the Study of Liver Diseases and the National Medical Association.
Dr. Abernathy is a native of the greater Washington, D.C. metropolitan area and loves not only serving, but also being involved in the communities in which he works and resides. When not treating patients, Dr. Abernathy enjoys spending time with his family and pursuing outside interests. These interests include jogging, mountain biking, skiing and participating in various community service and mentoring projects.
Muhammad Afzal, M.D., began his private practice in 1973 and joined Digestive Disease Associates in 1996. He received his medical degree from King Edward Medical College in Lahore, Pakistan. Dr. Afzal completed a rotating internship at the Franklin Square Hospital in Baltimore and a residency in internal medicine at St. Agnes Hospital. He performed his gastrointestinal fellowship at the Lahey Clinic in Boston and at St. Agnes Hospital in Baltimore.
Dr. Afzal is board certified in internal medicine and gastroenterology. He is past president of the Maryland Society of Gastrointestinal Endoscopy and a member of the American Gastroenterology Association and the American Society of Gastrointestinal Endoscopy.
Richard Andorsky, M.D., has been in practice in Columbia since 1992 and joined Digestive Disease Associates (DDA) in 2000. He received his medical degree from The George Washington University in Washington, D.C. Dr. Andorsky completed his internship and residency at Walter Reed Army Medical Center in Washington, D.C., and did his gastroenterology fellowship at Brooke Army Medical Center in San Antonio, Texas.
Following his formal training, Dr. Andorsky served in the U.S. Army Medical Corps as chief of the Department of Gastroenterology at Womack Army Medical Center, Fort Bragg, North Carolina. He served overseas during Operation Desert Storm and received the distinguished "Meritorious Service Medal" prior to his honorable discharge in 1991.
Dr. Andorsky has served in various leadership positions in the community to include: chief of the Gastroenterology subdivision at Howard County General Hospital (1996-2010), medical director of the Howard County Gastrointestinal Diagnostic Center (2000 – present) and president of Digestive Disease Associates (2007-present). His special interests include inflammatory bowel disease, disorders of the biliary tract and pancreas and functional disorders of the gastrointestinal tract (irritable bowel syndrome).
Dr. Andorsky is board certified by the American Board of Internal Medicine and the American Board of Gastroenterology. He is also a member of the American College of Gastroenterology and of the American Gastroenterological Association.
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Allen T. Banegura, M.D., joined Digestive Disease Associates (DDA) in 2007. He received his Bachelor of Science degree in Molecular Biology and Genetics from the University of Maryland College Park in 1995 and his medical degree from the University of Maryland School of Medicine in 2000. Dr. Banegura completed his internship and residency in internal medicine at the University of Michigan Health Systems in Ann Arbor. He performed his fellowship training in gastroenterology and hepatology at the University of Pittsburgh Medical Center.
During college Dr. Banegura served in the United States Marine Corps Reserves. He was awarded the National Defense Medal for Service in Desert Storm, the U.S. Marine Corps Selected Reserve Good Conduct Medal, and a certificate of Meritorious Service, prior his honorable discharge in 1998.
Dr. Banegura is board certified in internal medicine and gastroenterology and has an interest in diseases of the liver, pancreas, biliary, ERCP, Capsule Endoscopy and general gastroenterology. He is a member of the American Gastroenterology Association, the American Association for the Study of Liver Diseases, the American College of Gastroenterology and the American Society for Gastrointestinal Endoscopy.
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Abhijit Bhatia, M.D., joined DIgestive Disease Associates (DDA) in 2010. Dr. Bhatia received his Bachelor of Science degree in Biology, and his medical school degree from George Washington University in Washington, D.C. in 1998. He completed his residency in internal medicine at the Medical College of Virginia/Virginia Commonwealth University (MCV/VCU) in 2001, and his fellowship in gastroenterology in 2004 also from MCV/VCU. Prior to joining DDA, Dr. Bhatia worked as section lead for gastroenterology at Kaiser Permanente in Shady Grove. He also worked at Willis-Knighton Health System in Louisana, and was most recently at Mercy Philadelphia Hospital in Philadelphia.
Dr. Bhatia is board certified in Internal Medicine and Gastroenterology. He is a member of the American College of Gastroenterology. His interests include hepatitis C, biliary tract disorders, ERCP, capsule endoscopy and general gastroenterology.
Zahid W. Butt, M.D., started his clinical practice in Howard County and the Baltimore area in 1984. He is one of the founding members of Digestive Disease Associates (DDA). He graduated at the top of his medical school class from Nishtar Medical College in Pakistan. Dr. Butt performed his post graduate training at Prince George Medical Center, George Washington University, Georgetown University and the VA Medical Center in Washington, D.C.
He has served on the Quality Assurance Board of MD-IPA, the State of Maryland Technical Advisory Committee for Organ Transplantation and Donations and was a Physician Expert of the VA External Peer Review Program. Dr. Butt has an interest in clinical informatics which dates back to the early 90's when he was first appointed director of Clinical Informatics at St. Agnes Health Care. His expertise in clinical information systems has been indispensable to the growth and efficiency of the group's operations.
Dr. Butt is Board Certified by the American Board of Internal Medicine and the American Board of Gastroenterology.
Kester I. H. Crosse, M.D., joined Digestive Disease Associates (DDA) in 2003. Dr. Crosse received his Bachelor of Science degree in Biology from Hampton University in Virginia and his medical degree from the University of Maryland in 1997. He completed his internship and residency in internal medicine at the University of Maryland and performed his fellowship training in gastroenterology at the University of Maryland Medical System. While at the University of Maryland, he received specialized training in advanced endoscopic procedures. Dr. Crosse serves as the Assistant Chairman of the Department of Medicine at Howard County General Hospital and the treasurer of DDA.
Dr. Crosse is board certified in internal medicine and gastroenterology. He is a member of the American Gastroenterological Association and the American Society for Gastrointestinal Endoscopy.
Adinarayana Divakaruni, M.D. (a.k.a. Dr. Diva), opened his practice in Columbia in July, 1979. He received his medical degree from Guntur
Medical College of Andhra University in India. He completed his internship and residency in internal medicine at Prince Georges Hospital Center in Cheverly, Md., and during 1976 – 1977 was voted Best Resident of the Year. He performed his gastroenterology fellowship at Prince George’s General Hospital and John Hopkins Hospital.
Dr. Diva is one of the pioneers of gastroenterology in Howard County and has played an integral role in the growth of Howard County General Hospital and its gastroenterology department. He has served in numerous leadership positions over the years including: the director of the Howard County General Hospital Gastrointestinal Unit, assistant chairman of the Department of Medicine, the Chairman for the Quality Management Committee of the Department of Medicine and president of the Medical Staff. He is also a member of the Board of Trustees of Howard County General Hospital.
Dr. Diva is board certified in internal medicine and gastroenterology. He is a member of the American Gastroenterology Association, the American College of Gastroenterology, the Maryland Society of Gastrointestinal Endoscopy and the National Foundation of Ileitis and Colitis.
Christopher Y. Kim, M.D., F.A.C.G., F.A.C.P., joined Digestive Disease Associates (DDA) in 2002. He received a Bachelor of Science degree in Computer Science and Engineering from the Massachusetts Institute of Technology and his medical degree from Tufts University School of Medicine in Boston, Massachusetts in 1991. Dr. Kim completed his internship and residency in internal medicine at the University of Pittsburgh Medical Center (Pennsylvania). He performed his gastroenterology fellowship in Washington D.C. at the Georgetown University Medical Center / VA Medical Center / DC General Hospital / National Institutes of Health program. He spent an additional year at Georgetown University Medical Center training in endoscopic ultrasound.
In 1997, Dr. Kim joined the faculty at the Medical University of South Carolina in Charleston and later became the Section Chief of Gastroenterology at the Ralph H Johnson VA Medical Center in Charleston, South Carolina. In 2001, he went into private practice in Bethesda, Maryland. After one year, he elected to pursue an opportunity with DDA in their Columbia office and in 2005, he became a partner of DDA, relocating to the Catonsville office. In 2008, Dr. Kim began treating patients at Union Memorial Hospital.
In 2006, he received a Masters in Business Administration in Medical Services Management from Johns Hopkins University. Dr. Kim has been instrumental in implementing an electronic medical record for DDA and is a member of the American Medical Informatics Association and the Association of Medical Directors of Information Systems. He implemented wireless capsule endoscopy for the practice and introduced endoscopic ultrasound at St Agnes Hospital.
Dr. Kim is board certified in gastroenterology. He is also a Fellow of the American College of Gastroenterology, the American Society for Gastrointestinal Endoscopy (where he serves on the Practice Management and Web Education Committees), the American Gastroenterological Association, and the American College of Physicians. He is also a member of the American Association for the Study of Liver Diseases.
Preston Y. Kim, M.D., joined Digestive Disease Associates in 2005. He received his Bachelor of Arts degree in History from Duke University in 1993 and received his medical degree from the Medical College of Virginia/ Virginia Commonwealth University (MCV/VCU) where he met his wife Elizabeth, a radiologist with American Radiology Services. He completed his internship and residency in internal medicine at MCV/VCU, where he was selected as a Chief Resident in internal medicine. Dr. Kim performed his gastroenterology fellowship at the University of Maryland in 2005.
Dr. Kim is board certified in internal medicine and gastroenterology. He is a member of the American Gastroenterology Association and the American Society for Gastrointestinal Endoscopy. His interests include Endoscopic Retrograde Cholangiopancreatography (ERCP) and wireless capsule endoscopy. Dr. Kim serves as the chief of the Gastroenterology subdivision at Howard County General Hospital and Program Director of the Maryland Society of Gastrointestinal Endoscopy.
Susan J. Kohnke, CRNP., has been a Nurse Practitioner with Digestive Disease Associates (DDA) since 2005. She earned her Associates Degree in Nursing from Elgin Community College in Illinois in 1997 and furthered her education by obtaining a Bachelor of Science and a Masters Degree in Nursing from Johns Hopkins University School of Nursing in 2000.
Prior to obtaining her nursing degrees and becoming a Board Certified Nurse Practitioner, Susan was a medical practice manager in Illinois. This unique background of business and nursing (including oncology and rheumatology) enabled her to establish the DDA Infusions Centers in 2005. In the DDA Infusion Centers, she cares for patients with Crohn’s disease, ulcerative colitis, as well as providing peripheral care to patients with rheumatoid arthritis, psoriatic arthritis and psoriasis. Her areas of special interest include infusion nursing and treating patients with Hepatitis C. She is a frequent national speaker to healthcare groups on these topics.
Vijay Narayen, M.D., has been in practice in the Baltimore/Columbia area since 1984. He was the main force in bringing together eight independent practicing gastroenterologists to create Digestive Disease Associates (DDA) in 1994, and its subsidiary, Gastrointestinal Diagnostic Center (GIDC) of Catonsville. He also directed the creation of the first outpatient endoscopy center in Howard County, the Howard County Gastrointestinal Diagnostic Center.
Dr. Narayen received his medical degree from the Patna Medical College in India. After graduation he worked as a Senior House Officer in internal medicine in England before moving to Baltimore. Dr. Narayen was Chief Resident in internal medicine at St. Agnes Hospital in Baltimore and performed his subspecialty training in gastroenterology at the University of Medicine & Dentistry in Newark, New Jersey.
Dr. Narayen is the former medical director of GIDC of Catonsville and past president of DDA. He is responsible for initiating the clinical research arm of DDA, and has been the principal investigator for several clinical studies. He has done extensive research in the areas of ulcers, Crohn's disease, colon polyps and irritable bowel syndrome.
Dr. Narayen is board certified in internal medicine and gastroenterology. He is also a member of the American Gastroenterological Association, the American College of Gastroenterology and the American Society of Gastrointestinal Endoscopy. He serves as the President of the Maryland Society of Gastrointestinal Endoscopy.
Natarajan Ravendhran, M.D., M.B.A., A.G.A.F, F.A.C.G., joined Digestive Disease Associates (DDA) in 1995. He received his Bachelor of Science and medical degree from Stanley Medical College in Madras, India. Dr. Ravendhran completed his internship in surgery at Church Hospital in Baltimore and his residency in internal medicine at St. Agnes Hospital. He performed his fellowship training in Gastroenterology and Liver Disease at the University of Missouri Medical Center. In 2001, Dr. Ravendhran received a Masters in Business Administration in Medical Services Management from Johns Hopkins University.
Dr. Ravendhran has received additional specialized training in Liver Disease under a nationally-renown liver disease specialist, Dr. Eugene Schiff, at the University of Miami School of Medicine. He has performed extensive research in the areas of Hepatitis C, runs the Hepatitis C clinic for Digestive Disease Associates and directs numerous clinical trials involving Hepatitis B and Hepatitis C.
Dr. Ravendhran is board certified in internal medicine and gastroenterology. He is also a fellow of the American College of Gastroenterology and holds memberships in the American College of Physicians, the American Society of Gastrointestinal Endoscopy, the American Association of Physicians of Indian Origin, the Maryland State Society of Gastrointestinal Endoscopy and the American Gastroenterology Association. Dr. Ravendhran also serves as a clinical instructor at the University of Maryland School of Medicine and Chief of the Department of Gastroenterology and Liver Disease at St. Agnes Hospital. He is a past president of DDA.
Louis A. Salas, M.D., has been in private practice since 1992 and joined Digestive Disease Associates (DDA) in 1996. He received his Bachelor of Science degree in Biology from Loyola College in Baltimore and his medical degree from the Universidad Central Del Caribe School of Medicine in Cayey, Puerto Rico. He was an assistant resident at St. Agnes Hospital in the Department of Internal Medicine and a senior resident at the George Washington University Hospital. Dr. Salas performed his fellowship training in gastroenterology at The Johns Hopkins Bayview Medical Center and is a clinical instructor of gastroenterology fellows at Johns Hopkins Bayview Medical Center and an instructor of medicine at The Johns Hopkins University School of Medicine.
Dr. Salas is board certified in gastroenterology. He is the Vice-President for DDA and the medical director of the Gastrointestinal Diagnostic Center of Catonsville.
Lawrence F. Sorkin, M.D., received a Bachelor of Arts degree from Colgate University and his medical degree from the University of Health Sciences / Chicago Medical School. He completed his internship and residency in internal medicine at Montefiore Hospital and Medical Center in Bronx, New York, and performed his fellowship in gastroenterology and hepatology at the Veterans Administration Medical Center in Washington, DC. Prior to entering private practice in Howard County, Dr. Sorkin was acting chairman of the Department of Gastroenterology at Children’s Hospital National Medical Center, and assistant professor at George Washington University School of Medicine. In 1984, he became Chief of Gastroenterology for the Patuxent Medical Group. He joined Digestive Disease Associates in 2007.
Dr. Sorkin is board certified in internal medicine and gastroenterology. He was Chief of the Gastroenterology Section of Howard County General Hospital from 1988 to 1996. He is also a member of American College of Physicians, the American Gastroenterological Association, the American Society for Gastrointestinal Endoscopy and the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition.
Hossein Tavassolie, M.D., has been in private practice since 1983 and a partner with Digestive Disease Associates since 1995. He received his medical degree from the School of Medicine, University of Tehran, Iran. Dr. Tavassolie completed his internship at the St. Joseph Medical Center and his residency at St. Agnes Hospital. He performed his fellowship in gastroenterology at the University of Michigan, Ann Arbor, and served as an assistant professor of medicine at the University of Tehran.
He is board certified in internal medicine and gastroenterology and is a member of the American Gastroenterology Association and the American College of Physicians.
Ralph E. Updike, M.D., joined Digestive Disease Associates as a partner in 1995. He received a Bachelor of Science degree from the University of Maryland at College Park and his medical degree from the University of Maryland School of Medicine. Dr. Updike completed a rotating internship at St. Agnes Hospital followed by two years as a captain in the US Army. He completed his residency in internal medicine at St. Agnes Hospital which included one year as Chief Resident. He performed his fellowship in gastroenterology at the University of Maryland Hospital.
Dr. Updike is board certified in internal medicine and gastroenterology. He was Chief of Gastroenterology and Director of the Gastrointestinal Unit at St. Agnes Hospital from 1969 until 2006, and served as President of the hospital's Medical Staff in 1974. He also served two terms as president of the Maryland Society for Gastrointestinal Endoscopy.
Carl A. Wheeler, CFNP, joined Digestive Disease Associates in 2010.has been a nurse practiioner for over twelve years. His work in the field of gastroenterology includes time spent at Johns Hopkins and the Walter Reed Medical Center. He graduated from Howard University in 1998 with a master's degree and then certified as a family nurse practitioner. While at Hopkins, he served as the clinical coordinator to Dr. Marcia Canto's Photo-dynamic Therapy (PDT) program for the treatment of Barrett's esophagus and too managed both clinical and hospital patients for the Department of Gastroenterology. From 2007 - 2009, he worked in the Walter Reed gstroenterology clinic providing care to both veterans and active duty patients with common gi disorders. Mr. Wheeler attended the American Gastroenterology Association's mid-level provider program.
Prior to becoming a nurse practitioner, Mr. Wheeler was commissioned through the Army R.O.T.C. and served four years as an army officer. He serves as a Lieutenant Commander in the Naval Reserves (inactive status).
He resides in Annapolis, Maryland, with his wife and three boys.
Megan Dunnigan Willard, M.D., joined Digestive Disease Associates in 2007. Growing up in the Baltimore area, she graduated from Villa Julie College with a Bachelor of Science degree in biology where she was also a member of the National Honor Society. She received her medical degree from the University of Maryland School of Medicine where she also completed her internal medicine internship and residency and performed her fellowship training in gastroenterology.
Dr. Willard is board certified in internal medicine and gastroenterology. She is also a diplomate of the American Board of Internal Medicine.