naGateway Gastroenterology 17298 N. Outer 40 Road, Suite 200, Chesterfield, MO 63005naMain Office Location17298 N. Outer 40 Road, Suite 200Chesterfield, MO 63005 Monday: 8:00 AM - 4:00 PM Tuesday: 8:00 AM - 4:00 PM Wednesday: 8:00 AM - 4:00 PM Thursday: 8:00 AM - 4:00 PM Friday: 8:00 AM - 4:00 PM Saturday: Closed Sunday: Closed