-IBIS-1.5.0-
tx
digestive system
diarrhea
diagnoses

definition and etiology

definition:
increased volume, fluidity, or frequency of bowel movements

etiology:
There are several types of diarrhea:

• osmotic: this occurs in response to water-soluble, nonabsorbable solutes present in the colon. Typical causes include lactase deficiency, sorbitol and mannitol intolerance, vitamin C overdose, and poorly absorbed salts (e.g. magnesium sulfate). This type of diarrhea ceases when the provoking substance is avoided.

• secretory: occurs as a result of the intestines secreting salts, electrolytes, and water instead of absorbing them. Stimuli that initiate this process include bacterial toxins, unabsorbed dietary fat, bile acids, castor oil, some cathartics, some hormones, and some drugs.

• malabsorption: may result in either of the two types above. Sometimes in generalized malabsorption both types of diarrhea exist simultaneously (fat malabsorption resulting in secretory diarrhea and carbohydrate malabsorption resulting in osmotic diarrhea).

• exudative: results from inflammatory processes as they lead to increased leakages of plasma, serum proteins, mucus, pus, and blood. The fecal bulk and liquid levels then rise significantly, leading to diarrhea.

• altered intestinal transit: diarrhea may occur from either too long or too short a transit time. A shorter transit time causes malabsorption by not allowing the chyme enough time to bind to the surface of the intestinal tract. It is often seen after GI surgery (e.g. gastric resection, vagotomy). A longer transit time can cause malabsorption and diarrhea as the food is exposed and processed by the intestinal bacteria. Longer transit times are seen in iatrogenic stagnant loops, scleroderma GI disease, and with intestinal strictures.

Generally, if the cause is in the small intestine, the diarrhea is characterized by large quantities of watery and/or fatty stools. If the diarrhea is due to disease in or of the colon, the stool are frequent and often accompanied by blood, mucus, or pus. If the disease is rectal in origin, there are often frequent movements of a small amount of stool.

Consider deficient gall bladder function (Easley).

signs and symptoms

signs and symptoms:
• frequent watery/loose stools
• signs of anemia, dehydration, severe electrolyte loss.

pertinent history to obtain:
• time and place of onset
• history of eating out, traveling in a foreign country, drinking from natural water source
• duration and severity
• appearance of stools: overt blood or fatty/greasy/oily, foamy, etc.
• smell
• abdominal pain, cramping, tenesmus
• use of dietetic/diabetic products (usually contain sorbitol or mannitol)
• vomiting, loss of weight/appetite
• fever

lab findings:
• stool examination for blood, pus, mucus, fat, microorganisms, and parasites
• stool pH: normally > 6.0
• biopsy of rectal mucosa
• abdominal exam, rectal exam, proctoscopic exam
• O&P
• stool culture for Salmonella, Shigella, Campylobacter
• stool culture and sensitivity for enteropathogens

course and prognosis

The course solely depends on the cause. For example, virally-induced or sorbitol-induced diarrhea is almost always benign; diarrhea from ulcerative colitis or cholera may be fatal. Treatment should be directed to the cause; electrolyte and fluid replacement is important in severe cases.

differential diagnosis

• determine the cause


footnotes