Gastroenterology Institute of Southern California — Colonoscopy is considered the “gold standard” for… : Dr. Peyton Berookim is an exceptionally caring, friendly physician whom you’ll feel very comfortable with. This board-certified gastroenterologist offers care and treatment for digestive and liver diseases, bloating, constipation, IBS, heartburn, GERD, and abdominal pain. Dr. Berookim also provides services relating to diagnostic and therapeutic endoscopy as well as esophageal and colon cancer prevention. When it comes to gastrointestinal health, get leading-edge care and treatment from Dr. Berookim.