Blood in stool

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When referring to human feces, blood in stool looks different depending on how early it enters the digestive tract -- and thus how much digestive action it has been exposed to -- and how much there is. The term can refer either to melena, with a black appearance, originating from upper gastrointestinal bleeding; or to hematochezia, with a red color, originating from lower gastrointestinal bleeding. The term "blood in stool" is usually only used to describe visible blood and not fecal occult blood, which is found only after chemical testing. Evaluation of the blood found in stool depends on its characteristics, such as color, quantity and other features, which can point to its source.

In infants, the Apt test can be used to distinguish fetal hemoglobin from maternal blood.

Video Blood in stool

Pathophysiology

Common causes of blood in the stool include:

• Anal fissure
• Colorectal cancer
• Crohns disease
• Ulcerative colitis
• Internal hemorrhoids
• Inflammatory enteritis - inflammation of the small intestine, which may be caused by various forms of food poisoning as well as by other conditions:
  • E. coli enteritis, the most common cause of travelers' diarrhea
  • Campylobacter enteritis
  • Shigellosis
  • Salmonellosis (salmonella enteritis/samonella enterocolitis)
  • Bacterial gastroenteritis
    • Dysentery
  • Staphylococcus aureus
  • Radiation enteritis
• Diverticulosis
• Upper gastrointestinal bleeding
• Peptic ulcer disease
• Esophageal varices
• Gastric cancer
• Constipation

Maps Blood in stool

Evaluation

The tests that are considered for evaluation of the passage of blood in the stool is based on characteristic of bleeding (color, quantity) and whether or not the person passing blood has a low blood pressure with elevated heart rate, as opposed to normal vital signs. These tests are combined to determine which of the causes below is the source of bleeding.

• Digital rectal exam (DRE) and fecal occult blood test (FOBT)
• Colonoscopy
• Anoscopy
• EGD
• Capsule endoscopy
• CT Scan

Melena is defined as dark, tarry stools, often black in color due to partial digestion of the RBCs

Hematochezia is defined as bright red blood seen in the toilet either inside of, or surrounding the stool

Hematochezia is typically presumed to come from the lower portion of the GI tract, and the initial steps of diagnosis include a DRE with FOBT, which if positive, will lead to a colonoscopy. If bleeding is large in volume, the evaluation may also include an EGD. If no source of active bleeding is found on these examinations, a capsule endoscopy may be performed, in order to more closely examine the small bowel, which cannot be seen with the other types of studies. With melena, a DRE with FOBT is often also performed, however the suspicion for a source from the upper GI tract is higher, leading first to the use of EGD with the other tests utilized if no source is identified. The anoscopy is another examination, which can be used as an adjunct to the colonoscopy, which exams the rectum and distal portion of the descending colon.

Other features

Mucus may also be found in stool.

A texture described as tarry stool is generally associated with dark black stool seen in partially digested blood. This is generally associated with melena.

Patient Age

Age is an important indicator for the diagnostic workup that is considered for the presence of blood in stool, as a result of the diagnoses that tend to affect each age group.

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See also

• Fecal occult blood

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References

Source of the article : Wikipedia