Hello and welcome to HCM, Light colored stool occurs in obstruction of the biliary tree. Obstruction of biliary tree can lead to absence of reduced amount of bile pigments which are responsible for characteristic color of the stools. Colonoscopy will assess the large intestine only so it will be unremarkable in abnormalities of upper gastrointestinal tract. Bloating of abdomen can occur in large number of conditions like indigestion, gastritis, cholelithiasis or other disorders of liver. Thus, an evaluation of liver and biliary tract is required to know the cause of light colored stools. Consultation with a gastroenterologist is required for further evaluation. Thanks and take care Dr Shailja Puri