investigation must be logical and structured and can be divided into three stages : the initial work-up ( sigmoidoscopy , stool examination , screening blood tests ) , anatomical and functional assessment of the gastrointestinal tract , and further investigation of the difficult case ( osmotic or secretory diarrhoea ? , hormone levels , tests for laxative abuse , perfusion studies , laparotomy , etc . )
C0037075
sigmoidoscopy
C0017189
gastrointestinal