2. Diarrhea and Constipation Flashcards
Main 6 GI Functions
- Motility - movement of food and liquid by peristalsis
- Secretion - exocrine and endocrine hormone secretions
- Digestion - mechanical breakdown of food into smaller units
- Absorption - passage of digested end products into blood or lymph
- Immune Barrier - intestinal mucosal barrier, Gut Associated Lymph Tissue (GALT)
- Storage and Elimination - temporary storage and elimination of indigestible products
Nutrient Absorption
- Small Bowel - where most macronutrient digestion and the absorption of carbohydrates, proteins, fats, vitamins and minerals occurs
- Colon - largely absorbs water and electrolytes. Also extracts nutrients through bacterial fermentation to short-chain fatty acids
Normal Intestinal Fluid Absorption (Amount)
- 9-10 L of fluid enters the jejunum daily
- Small bowel absorbs 90% of this –>
- 800-1000 ml of fluid enters the colon daily
- Colon absorbs 90% of this –>
- 80-100 ml is excreted each day in feces
If more fluid passes the ileocecal valve, colon can absorb up to 3-4 L
Normal Intestinal Fluid Absorption (Osmolality)
-
At baseline, absorption in the intestine is isotonic
- because the osmolality of intestinal fluid is always the same as plasma
-
Net osmosis occurs due to a concentration gradient established by active transport of solutes into mucosal cells
- Water follows
Define Diarrhea
OBJECTIVELY:
Diarrhea - stool frequency of 3+ BMs/day or stool weight of > 200 g/day
SUBJECTIVELY:
- Urgency
- Increased Stool Frequency
- Loose Stools
Classify Diarrhea
by Length of Time
- ACUTE - up to 2 weeks
- PERSISTENT - > 2 weeks - 4 weeks
- CHRONIC - > 4 weeks
Discuss the Bristol Stool Chart
Describes defecation on a spectrum from constipation - diarrhea
- 1 - nuts that are hard to pass
- 2 - lumpy sausage
- 3 - cracked sausage
- 4 - smooth sausage
- 5 - soft blobs with clear edges
- 6 - mushy stool
- 7 - watery stool
Pathophysiology of Diarrhea
1-2% decrease in intestinal water absorption results in average fecal water excretion of 100 ml (enough to increase stool weight above 200 g)
Diarrhea Mechanisms
Think: He “CRIIAD and got diarrhea”
-
Circulating secretagogues
- Neuroendocrine tumors
-
Reduction of mucosal surface area (malabsorption)
- Mucosal disease, resection
-
Infection
- C. difficile, C. jejuni, E. coli, V. cholera
-
Inflammation
- IBD, microscopic colitis, vasculitis
-
Absence of ion-transport mechanism
- Congenital electrolyte malabsorption
-
Disordered regulation (altered motility)
- Postvagotomy, hyperthroidism, diabetic neuropathy
Difference between Secretory and Osmotic Diarrhea
SECRETORY DIARRHEA:
- Electrolytes account for most of the luminal osmolality
- Can occur day and night
- Continues with fasting because issue is with absorption of ions, not dietary intake
OSMOTIC DIARRHEA:
- Due to unabsorbable solute
- Stops with fasting because issue is with dietary intake
Fecal Osmotic Gap Purpose, Calculation, Interpretation
-
Definition:
- Fecal Osmotic Gap - used to differentiate between secretory and osmotic diarrhea
-
Calculation:
- Stool Osmotic Gap = 290 mosm/kg - 2 (stool Na + stool K)
-
Interpretation:
- Secretory = < 50
- Intermediate = 50-125
- Osmotic = > 125
Approach to Diarrhea
1. Diarrhea, Fecal Incontinence, or Impaction?
-
Incontinence - involuntary release of rectal contents
- Do a DRE to check sphincter tone
-
Impaction - inability to expel large fecal mass through the anus. Overflow diarrhea can happen when liquid stool passes around the impaction
- Major risk factor is chronic constipation, so ask about this
2. Rule out Drug-Induced Diarrhea
- Ask if on:
- Vasoconstricting Agents - decrease mesenteric blood flow
- Caffeine - affects activation of transporters/receptors
- Antacids/Laxatives - cause osmotic diarrhea
- Antiarrhythmics - cause secretory diarrhea
- Antibiotics - alter colonic flora, cause secretory diarrhea
- NSAIDs - cause intestinal irritation, cause secretory diarrhea
- Establish a temporal relationship between starting the drug and the onset of diarrhea
3. Distinguish acute from chronic diarrhea.
4. Categorize diarrhea as inflammatory, fatty, or watery.
- Inflammatory –> Colonic evaluation
- Fatty –> Mucosal - inadequate mucosal transport due to celiac’s or mesenteric ischemia –> Endoscopy with biopsy
- Fatty –> Luminal - inadequate breakdown of triglycerides due to pancreatic insufficiency –> CT or EUS or SIBO –> breath tests or aspirates
- Watery –> Secretory or Osmotic –> Consider small bowel and colonic evaluation
5. Consider factitious diarrhea
- In patients who remain undiagnosed after thorough evaluation
- Usually surreptitious laxative ingestion
- Could see Melanosis coli - brownish discoloration of colonic mucosa due to laxatives like senna, cascara, and rhubarb but can be from other conditions
ACUTE DIARRHEA:
History
-
PMH:
- Age –> Institutionalized (drugs)?
- Diseases –> Diabetes, AIDs
- Medications
- Travel –> Common exposure or direct transmission?
- Infection
- Onset
-
Characteristics:
- Frequency
- Blood
- Mucus
- Oil Droplets and Food Particles
- Watery
- Diarrhea during day and night (secretory) or just the day?
- Relievers: Fasting?
- Treatments
- Symptoms: Abdominal Pain, Bloating, Cramping, Flatuence, Fever, Weight Loss
Mild vs. Severe Acute Diarrhea
MILD
- 7 days or less
- No signs of dehydration
- No signs of toxicity, fever, bleeding
- Supportive care ok. No workup is generally needed
SEVERE
- Long duration, elderly patient, or immunocompromised patient
- Signs of dehydration
- Patient is toxic-appearing, febrile, or complains of bloody diarrhea
- Supportive care + Workup
ACUTE NON-INFLAMMATORY AND INFLAMMATORY INFECTIOUS DIARRHEA:
Etiology
Clinical Presentation
Workup
ACUTE NON-INFLAMMATORY INFECTIOUS DIARRHEA:
ETIOLOGY:
Typically
- Viruses
- Non-invasive Bacteria
Some parasites can cause this type of diarrhea
CLINICAL PRESENTATION:
- Watery, Non-Bloody Diarrhea
- Nausea +/- Emesis
- +/- Abdominal Cramping and Bloating
WORKUP:
Generally not needed as illness is self-limited
ACUTE INFLAMMATORY INFECTIOUS DIARRHEA:
ETIOLOGY:
- Invasive bacteria
- Parasites
CLINICAL PRESENTATION:
- Fever
- Frequent, small-volume bloody stools
- Abdominal Cramping
- Urgency
- Tenesmus
WORKUP:
- Stool Studies
- Inflammatory Markers (ESR, CRP)
- Fecal Leukocytes
- Fecal Calprotectin
ACUTE NON-INFLAMMATORY INFECTIOUS DIARRHEA:
Differential
VIRAL:
- Norovirus
- Rotavirus
BACTERIAL:
- Vibrio cholerae
- Enterotoxigenic E. coli
- Clostridium perfringens
- Staph aureus
PARASITIC (PROTOZOAL):
- Giardia Lamblia
- Cryptosporidium
- Cyclospora
NOROVIRUS:
BUZZ WORDS
History
Transmission
Incubation
Duration
Diagnosis
Management
BUZZ WORDS:
Most common cause of epidemic gastroenteritis worldwide
HISTORY:
- Cruise ships
- Restaurants/Catered Events
- Schools
- Military Bases
- Prisons
TRANSMISSION:
- Fecal-oral (shellfish, salads, sandwiches, frosting, produce)
INCUBATION:
1-2 days
DURATION:
12-60 hours
DIAGNOSIS:
Clinical. RT-PCR amplification rarely performed
MANAGEMENT:
- Fluids
- Electrolyte Repletion
- Time
ROTAVIRUS:
BUZZ WORDS
History
Transmission
Incubation
Diagnosis
Management
Prophylaxis
BUZZ WORDS:
- Most common cause of severe gastroenteritis IN CHILDREN worldwide
HISTORY:
- Children 6 months-2 years
- Healthcare Workers
- Nosocomial Exposure
- Immunocompromised / Long-Term Care Facility Residents
TRANSMISSION:
Fecal-oral
INCUBATION:
< 48 hours
DIAGNOSIS:
- Clinical
- Labs may show signs of dehydration (metabolic acidosis, electrolyte abnormalities, elevated BUN/Cr)
- ELISA or PCR amplication of viral shedding in stool after 1-4 days of illness
MANAGMENT:
- Fluids
- Electrolyte Repletion
- Time
PROPHYLAXIS:
- RotaTeq (3 doses total given at 2, 4, and 6 months)
- Rotarix (2 doses total given at 2 and 4 months)
VIBRIO CHOLERAE:
BUZZ WORDS
History
Transmission
Main Symptom
Diagnosis
Management
BUZZ WORDS:
Rice water stools
HISTORY:
Overcrowding (natural disasters, refugee camps)
TRANSMISSION:
Fecal contamination of water, fish, undercooked grains, and produce
MAIN SYMPTOM:
MASSIVE, watery diarrhea (rice water stool)
DIAGNOSIS:
- Stool culture is GOLD STANDARD
- WHO clinical definition when laboratory testing not possible
- No Cholera Outbreak: Any patient 2+ presenting with acute watery diarrhea and severe dehydration / dying from acute water diarrhea.
- Cholera Outrbreak: Any person presenting with acute watery diarrhea / dying from acute watery diarrhea.
MANAGEMENT:
HYDRATION!
ENTEROTOXIGENIC E. COLI:
BUZZ WORDS
History
Transmission
Incubation
Management
BUZZ WORDS:
Leading cause of Traveler’s Diarrhea
HISTORY:
Travel to resource-limited regions of the world
TRANSMISSION:
Fecal oral contamination of food or water
INCUBATION:
1-3 days
MANAGEMENT:
- Fluid
- Electrolytes
- Nutritional Support
FOOD POISONING:
Symptoms
Etiology
SYMPTOMS:
- Fever
- Nausea +/- Vomiting
- Abdominal Cramping
- Diarrhea
ETIOLOGY:
- Bacillus Cereus
- Clostridium Perfringens
- Staph Aureus
