Changes in Stool Consistency
Loose, greasy stool
Loose, shiny stool that is difficult to flush, with visible fat droplets on the surface or in the water, is referred to as fatty stool (steatorrhea).
This usually occurs due to severe pancreatic insufficiency, pancreatic cancer, or small intestinal diseases (e.g., celiac disease).
In such cases, fat excretion in the stool should be measured over 3 days while following a standard diet containing 100g of fat. If confirmed, further steps include diagnosing pancreatic or intestinal disease and starting enzyme replacement therapy.
Foamy, explosive stool
Often a sign of intestinal infection, and may also indicate digestive or absorption disorders.
Pencil-shaped stool
This describes a thin, narrow stool resembling the diameter of a pencil.
It may result from narrowing of the rectal passage due to cancer or, less commonly, due to inflammation or scarring in the anal area.
This change warrants medical examination, starting with a digital rectal exam.
Changes in Stool Color
Black, tarry stool (melena)
This color suggests the presence of digested blood.
The source of bleeding is usually in the stomach or duodenum. If the movement of intestinal contents is slow and bleeding is mild, the source may also be in the beginning of the colon (e.g., cecum near the appendix).
To confirm that black color is due to blood, an occult blood test (available over-the-counter) can be done.
If positive, urgent medical evaluation is necessary, including blood tests, iron levels, and gastrointestinal endoscopy.
In some cases, more advanced diagnostics may be required.
Note: Black stool can also be caused by iron supplements, bismuth, or activated charcoal. In such cases, the occult blood test will be negative and no further testing is usually required.
Light-colored, yellowish, or clay-colored stool
This often indicates a bile flow obstruction (cholestasis), affecting bile release from the liver into the intestines.
Obstruction can occur anywhere from liver cells to the duodenal papilla.
Cholestasis may be accompanied by jaundice, dark urine, and generalized skin itching.
White stool
This may appear after a contrast study of the GI tract involving oral barium sulfate.
The contrast agent can turn the first bowel movement white.
Loose, greenish stool
Most likely a sign of an intestinal infection.
Diarrhea and fever are common accompanying symptoms.
Pathological Additions in Stool
Presence of blood
Fresh blood covering the stool or only appearing on toilet paper is usually linked to hemorrhoids.
Blood mixed with stool or appearing as clots may indicate internal bleeding within the intestines.
In both cases, medical investigation is necessary. A colonoscopy is often recommended to identify the source and to rule out colon cancer.
Presence of mucus
Mucus covering the stool may result from functional disorders or mild intestinal inflammation.
It may also appear together with blood or pus.
Presence of parasites
Visible parasites or their segments (such as tapeworms) clearly require a parasitological stool examination and appropriate treatment.