PAYMENT ✓ Most Insurances ✓ Most HMOs ✓ Medi-Cal ✓ Cash Patients Procedures Dr. Tieng provides comprehensive gastroenterology services and treatments using the most up-to-date technologies. APPOINTMENTS (909) 255-7200 FOR EMERGENCIES, DIAL 911 Colonoscopy A tiny camera examines your large intestine. Upper Endoscopy A tiny camera examines your upper upper digestive system. Esophageal Dilation A procedure stretches the narrow area of your esophagus. Flexible Sigmoidoscopy A tiny camera examines your lower large intestine.