Colour - Normal faeces are light to dark brown in colour due to the presence of bile pigments. Coloured stools occur in obstructive jaundice due to absence of bile pigments in the stool. Tarry or black stools occur in upper gastrointestinal haemorrhage due to altered blood. Tarry stools also occur following iron administration. Consistency - Normal stools are well formed.
Watery stools occur in diarrhoea.
Hard faeces suggest constipation. Flattened and ribbon like stools occur in obstruction in the lumen of the bowels. Palel, bulky, semi-solid, frothy stools, occur in malabsorption syndrome. Odour - Normal odour of the faeces is due to presence of indole and skatole, which is stronger than after a meat diet. In nursing infants a typical sour odour due to the presence of fatty acids occurs.