Tim Sowerby, MD 

Dr. Sowerby graduated from Charing Cross and Westminster Medical School, University of London, England in 1987. He completed pre-registration house officer appointments (internships) in general surgery and medicine at the Queen Elizabeth Hospital, Kings Lynn and the West Middlesex University Hospital, London respectively. These were followed by senior house office appointments in family practice and medicine at Queen Elizabeth Hospital, Kings Lynn. In 1990 he moved to California. After a residency in internal medicine at Kaiser Foundation Hospital, San Francisco he completed a fellowship in gastroenterology Kaiser Foundation Hospital, Los Angeles. From 1995 to 2000 he was a member of the Permanente Medical Group practicing gastroenterology in both San Francisco and San Rafael. In 2000, Dr. Sowerby entered private practice in Marin County. Dr. Sowerby is Board Certified in Gastroenterology.







Natalie Lee, MD

Dr. Lee is a graduate of Stanford University and University of California, San Francisco medical school. She completed an internship and residency in internal medicine at University of California, San Francisco in 2005 and completed her fellowship in gastroenterology at University of California, San Francisco in 2008. She entered private practice in Marin County in 2008. Dr. Lee is Board Certified in Internal Medicine and Gastroenterology.

 John Bettinger, MD

A native of Marin County, Dr. Bettinger received his Bachelor’s degree from Yale University, graduating summa cum laude. He received his medical degree at the University of California, San Francisco in 1986. After internship at UCLA, he completed his residency at the University of New Mexico where he served an additional year as Chief Resident. Dr. Bettinger returned to UCSF in 1990 for gastroenterology fellowship, after which he practiced at Kaiser South San Francisco for four years. From 1996 to 2009, Dr. Bettinger was in private practice with Southwest Gastroenterology Assoc. in Albuquerque, New Mexico. He moved home to Marin in 2009. He currently serves as chairman of the Department of Medicine at Marin General Hospital. Dr. Bettinger is board certified in Internal Medicine and Gastroenterology.


Wendy Davis, MD

Dr. Davis completed her B.A. at Yale, graduating summa cum laude. She received her medical degree from Duke University School of Medicine and was a member of A.O.A. She completed her residency in Internal Medicine and her fellowship in Gastroenterology at Duke University Medical Center. She then joined faculty at Duke, where she served for 17 years. Dr. Davis is board certified in Gastroenterology, and she is a member of the American College of Gastroenterology and the American Society for GI Endoscopy. Dr. Davis practices general gastroenterology, with a special interest in reflux and esophageal diseases, colon cancer screening and surveillance, and functional bowel disease.

Vikram Malladi, MD

Dr. Vikram Malladi graduated from the University of Chicago with a bachelors of science in biochemistry. He then attended the University of Texas Health Science Center in San Antonio followed by an internal medicine residency and gastroenterology fellowship at Baylor College of Medicine. After completing his fellowship in 2006, Dr Malladi joined his father in a private practice located in East Texas relocating to the Bay Area in 2008 to practice gastroenterology at the Kaiser Permanente South San Francisco Medical Center. In July 2014 Dr Malladi returned to private practice joining Marin Gastroenterology.
Dr Malladi is board certified in gastroenterology with a special interest in inflammatory bowel, biliary and pancreatic diseases.


Ripple Sharma, MD, FACG

Dr. Sharma, a native Californian, received her B.A. in Psychology from Creighton University in 2003, and her M.D. from Creighton University’s School of Medicine in 2007. She returned to California, completing an Internal Medicine residency at University of California Davis Medical Center where she was subsequently appointed as Chief Resident. In 2014 she completed a fellowship in Gastroenterology & Hepatology at California Pacific Medical Center in San Francisco.

Dr. Sharma is a board certified gastroenterologist with particular interests in liver and inflammatory bowel diseases together with colon cancer screening and prevention.

 Christopher Hogan, MD

Dr. Hogan graduated with Honors and a double major in genetics and philosophy from the University of Wisconsin, Madison. He received his medical degree from the University of Rochester School of Medicine with an NIH Clinical and Translational Sciences Award and a distinction in research. He completed his Internal Medicine residency with a healthcare leadership track distinction at Mount Sinai Hospital in New York City. He completed his fellowship in Gastroenterology at UC Irvine and then relocated from Southern California to join Marin Gastroenterology. In his spare time, Dr. Hogan enjoys soccer, cycling, skiing, and exploring the Bay Area with his wife, son, and toy poodle Brooklyn.

Dr. Hogan is a board certified Gastroenterologist with a special interest in pancreatic and bile duct conditions, inflammatory bowel disease, and colon cancer screening and prevention.