Black tarry stools can have various causes, ranging in severity from 'needs attention' to 'life-threatening'. Finding the true cause means ruling out or confirming each possibility – in other words, diagnosis.
Diagnosis is usually a complex process due to the sheer number of possible causes and related symptoms. In order to diagnose black tarry stools, we could:
|Possible Urgent Medical Need||5%||Ruled out|
|Carcinoid Cancer||0%||Ruled out|
Do you ever pass black, tarry stools?
Possible responses:→ No / don't know
→ Yes, sometimes slightly black/tarry
→ Yes, often slightly black/tarry, sometimes very
→ Yes, my stools are usually/always very black/tarry
Significant blood in the stool from a carcinoid tumor can cause bowel movements to become black.
Bleeding from an ulcer may occur in the stomach or the duodenum, and sometimes is the only symptom. Rapid bleeding causes bowel movements to become black or even bloody.
Black, tarry stools usually result from bleeding that occurs high up in the digestive tract – for example, in the stomach or first segment of the small intestine (duodenum); blood in the stomach turns black when exposed to stomach acid and enzymes. A single severe bleeding episode can produce tarry stools for as long as a week, so continuing tarry stools do not necessarily indicate persistent bleeding.