Differential Diagnosis for Green Stool

• Single Most Likely Diagnosis
  • Bile pigment: The most common cause of green stool is the presence of bile pigments, which are produced during the digestion process. Bile is a greenish-yellow fluid produced by the liver and stored in the gallbladder. When bile is released into the intestines, it can give stool a greenish color.
• Other Likely Diagnoses
  • Viral gastroenteritis: Certain viruses, such as norovirus, can cause green stool due to the rapid transit of food through the digestive system.
  • Food coloring: Consuming foods or drinks with green food coloring can temporarily turn stool green.
  • Iron supplements: Taking iron supplements can cause green or black stools due to the oxidation of iron.
• Do Not Miss Diagnoses
  • Giardiasis: An intestinal infection caused by the Giardia parasite, which can lead to green, frothy, and foul-smelling stools.
  • Inflammatory bowel disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause green stool due to inflammation and bleeding in the digestive tract.
  • Intussusception: A rare condition where a part of the intestine telescopes into another part, which can cause green, bloody stools.
• Rare Diagnoses
  • Malabsorption disorders: Certain conditions, such as celiac disease or pancreatic insufficiency, can lead to malabsorption of nutrients and cause green stool.
  • Biliary obstruction: A blockage in the bile ducts can cause green stool due to the accumulation of bile pigments.
  • Pseudomembranous colitis: A rare condition caused by an overgrowth of Clostridioides difficile bacteria, which can lead to green, watery stools.