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, typically originating from upper gastrointestinal bleeding; or to hematochezia, with a red color, typically originating from lower gastrointestinal bleeding.
In infants, the Apt test, a test that is particularly useful in cases where a newborn has blood in stool or vomit,
Differential diagnoses
Blood in the stool can come from many sources. The causes range from not harmful to very serious conditions. A common way to divide causes of bleeding is based on the source of bleeding. The GI tract can be divided into upper and lower, with some causes of bleeding affecting the entire tract (upper and lower).
Blood in the stool often appears different depending on its source. These differences can help when diagnosing these conditions. The rate of bleeding can also make blood in the stool look different from typical cases.
[Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J. eds. (Part 14: The Gastrointestinal System, Chs 344, 345, 348, 351, 353, 365) Harrison's Principles of Internal Medicine, 19e New York, NY: McGraw-Hill; 2014.]
Upper GI tract
The upper GI tract is defined as the organs involved in digestion above the ligament of Treitz and comprises the
esophagus,
stomach, and
duodenum.
Upper gastrointestinal bleeding is typically characterized by
melena (black stool). Bright red blood may be seen with active, rapid bleeding.
Pathophysiology
The development of blood in a person's stool results from a variety of conditions, which can be divided into major categories of disease. These broad categories include cancerous processes or abnormal structure of bowel wall, inflammatory disease, colitis caused by infection or medications and vascular compromise.
Cancer
Gut wall changes
Motility
The gut wall is important for the movement of waste products through the GI tract. Repetitive attempts to have a bowel movement can lead to tearing around the exit of the
rectum (anal fissure)
Structural
This list of diagnoses include diseases in which the wall of the bowel is compromised by disease.
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Peptic ulcer disease
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Nonsteroidal anti-inflammatory drugs—the use of these medications results in a structural change in the wall of the gut, namely ulcers, and potential blood in the stool.
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H. pylori infection—this bacterial infection can erode the wall of the stomach or duodenum, leading to a structural change in the stomach wall and bleeding in the stool.
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Chronic disease
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Diverticulitis
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Meckel's diverticulum is a congenital remnant of the omphalo-mesenteric duct that connected the fetal yolk sac to the intestines which is normal closed off and destroyed during the process of development.
Inflammatory bowel
Diseases causing inflammation in the GI tract can lead to blood in the stool.
Inflammation can occur anywhere along the GI tract in Crohn's disease,
or in the colon if a person has ulcerative colitis.
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Crohn's disease
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Ulcerative colitis
Colitis
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Enteritis—inflammation of the small intestine, which has many causes including autoimmune conditions (e.g. Crohn's disease), certain drugs (e.g. ibuprofen), radiation therapy, and Coeliac disease.
Infectious colitis
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Food poisoning—the bacteria that is associated with bloody diarrhea is typically Escherichia coli
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Campylobacter enteritis
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Shigellosis
[ Shigellosis , National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention]
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Salmonellosis (Salmonella enteritis/Salmonella enterocolitis)
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Bacterial gastroenteritis
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Campylobacter jejuni
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Clostridioides difficile
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Escherichia coli enteritis—most common cause of travelers' diarrhea
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Salmonella enterica
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Shigella dysenteriae
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Staphylococcus aureus
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Entamoeba histolytica
Drug-induced colitis
Vascular compromise
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Angiodysplasia of the GI tract
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Arteriovenous malformation
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Anal fissure
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Anal intercourse
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Esophageal varices
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[ Hemorrhoids , National Digestive Diseases Information Clearinghouse, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health.][ Hemorrhoids: Symptoms, Mayo Clinic.]
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Internal hemorrhoids are covered by a layer of mucosa and epithelium, making them more likely to bleed, but typically do not cause pain.
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External hemorrhoids are less likely to bleed, they are covered by a different type of epithelium (squamous) but can cause significant pain as a result of thrombosis of the blood vessels within them.
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Polypectomy during a colonoscopy can lead to a small amount of bleeding seen in the stool after the procedure
Other causes
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Blood in the diet, for example, the traditional diet of the Maasai people includes much blood drawn from cattle.
Diagnosis
The tests that are considered to evaluate of the passage of blood in the stool are based on the characteristics 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.
The following tests are combined to determine the causes of the source of bleeding.
Melena is defined as dark, tarry stools, often black in color due to partial digestion of the red blood cells.
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 digital rectal exam with fecal occult blood test, which if positive, will lead to a colonoscopy.[Scott Moses. "Upper Gastrointestinal Bleeding". www.fpnotebook.com. Retrieved 2017-11-26.][Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 19e New York, NY: McGraw-Hill; 2014.]
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| Bright red | Hematochezia | Occasional occurrence of blood | Small | Hemorrhoids, inflammatory conditions, polyps |
| Bright red | Hematochezia | Increased stooling, blood with every stool | Large | Rapid bleeding, e.g. ulcer, varices |
| Dark red/black | Melena | Blood with every stool | Difficult to measure, mixed in with stool | Slow bleeding, cancer, ulcer, (peptobismol and Iron supplement use can be mimics) |
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.
Patient age
A person's age is an important consideration when assessing the cause of the bleeding.
|
| <20 years | Pediatric | Inherited/autoimmune condition or structural |
| 20–60 years | Middle aged | Inherited/autoimmune condition, vascular malformation |
| >60 years | Elderly | Vascular malformation, liver disease, cancer |
Treatment
Treatment of bloody stool depends largely on the cause of the bleeding. Bleeding is commonly associated with symptoms of fatigue,
dizziness,
, or even shortness of breath, and these associated symptoms also require treatment.
These symptoms are the result of blood loss, and occur due to a lack of red blood cells circulating in the
Blood vessel system, resulting in less oxygen reaching the tissues and organs.
Blood in stool can be associated with serious complications as a result of blood volume loss (
hemorrhage) or a slow leak of the blood leading to low levels of
hemoglobin in the circulating blood (
anemia).
Anemia
Anemia is a common complication of blood in the stool, especially when there is a large amount of blood or bleeding occurs over a long period of time.
Anemia is also commonly associated with an iron deficiency, due to the importance of
iron in the formation of red blood cells.
When anemia is diagnosed as a result of blood in the stool, vitamins that are important for red blood cell formation (
folate, vitamin B12, and
vitamin C) are frequently prescribed in order to ensure that all the materials are available for those cells that are made.
Specific treatment
Diagnostic measures can be used as interventions to help stop bleeding in some cases. Bleeding that occurs due to a
neoplasm (cancer growth) can be treated using
colonoscopy and clipping, surgical intervention, or other measures, depending on the form and stage of cancer.
Similarly,
stomach cancer is treated depending on the staging, although typically requires surgical and medical therapy.
The treatment for motility issues, namely constipation, is typically to improve the movement of waste through the GI tract. This is done by using stool softeners (which work by pulling water into the stool while in the colon), addition of fiber to the diet, and use of osmotic laxatives (which help fluid movement through the colon, improving overall motility). Improving a person's gut motility can reduce the straining during defecation and decrease the risk of developing .
Colitis can be divided into infectious and drug induced, as can the treatment for these conditions. With infectious colitis, treatment is pathogen dependent, and generally requires the use of antibiotics. With drug-induced colitis, treatment typically involves removal of the offending agent, as is the case in nonsteroidal anti-inflammatory drugs induced peptic ulcer disease,
Structural compromise leading to blood in stool is caused by a variety of conditions, and therefore requires different treatment for each condition. Peptic ulcer disease alone can be divided into multiple causes, but is generally initially controlled primarily with a proton pump inhibitor, with the addition of an H2 blocker, or in serious cases, requiring surgical intervention.
Inflammatory bowel disease is also divided into separate conditions, namely ulcerative colitis and Crohn's disease, which have different medical treatment regimens, and may require surgical intervention in more serious conditions.
See also
External links
