Acute Diarrhea – Approach

acute diarrheaThere is no standard definition of diarrhea. Diarrhea may be defined with one or combination of the following criterion:

  1. Change in consistency of stool: Increased water-content
  2. Increase in freqency of stool: >3 times per day
  3. Increase in weight of stool: >200 grams per day or >10 grams/kg/day

Among all these, diarrhea is best explained by the change is consistency of the stool. Acute diarrhea is short-lived i.e. less than 2 weeks.


1. Infectious:

  • Viral (more common): Rotavirus, Norwalk (calcivirus), Adenovirus, Astrovirus
  • Bacterial:
    • With or without dysentery: Enterohemorrhagic E.coli, Shigella, Campylobacter, Plesiomonas shigelloides, Salmonella
    • Without dysentery: Enterotoxigenic E.coli, Enteropathogenic E.coli, Vibrio cholera, Aeromonas, Bacillus cereus, Clostridium difficile, Clostridium perfringes, Staphylococcus aureus
  • Parasitic:
    • With or without dysentery: Entamoeba histolytica, Trichuris trichuria
    • Without dysentery: Giardia lamblia, Cryptosporidium parvum, Cyclospora cayetanensis, Isospora belli
  • Fungal: Candida albicans

2. Non-infectious:

  • Drugs: Antibiotics and laxatives
  • Allergic colitis
  • Lactose intolerance
  • Radiation/Chemotherapy enteritis
  • Appendicitis
  • Niacin deficiency (Pellagra)
  • Copper or Zinc toxicitiy


1. Community acquired diarrhea

2. Hospital acquired diarrhea:

  • Onset of diarrhea 3 days after hospitalization and not incubating at the time of admission to hospital
  • Related to antibiotic use , non-antibiotic medications or tube feeds


In healthy adults, 93% of fluid entering the intestines is absorbed by the time it reaches the ileocecal valve. Children become volume depleted more rapidly than adults (due to an increased surface/volume ratio and limited renal compensatory capacity). Loss of electrolytes in stool:

  • Sodium: 20-25 mEq/L
  • Potassium: 50-70 mEq/L
  • Chloride: 20-25 mEq/L.
 Osmotic diarrheaSecretory diarrhea
Response to fastingDiarrhea stopsDiarrhea continues
Volume of stool<200 ml/day>200 ml/day
Stool Na+<70 mEq/l>70 mEq/l (Increased Na+ and K+ secretion in stool)
Stool osmotic-gap i.e. 2 (Na + K)>100 mOsm/kg<50 mOsm/kg
Reducing substancesPositiveNegative
Stool pH<5


  1. Osmotic diarrhea: Lactose intolerance, Malabsorption via damaged intestinal epithelial cells (rotavirus, shigella, etc.)
  2. Secretory diarrhea: Via enterotoxins or invasion of bowel mucosa


Symptom/SignsMild (A)Moderate (B)Severe (C)
General conditionAlert, activeRestless, irritableLethargic, unresponsive
EyesNormalSlightly sunkenVery sunken
ThristNormalEagerly drinkingNot able to drink
Skin pinchInstant recoilRecoil in <2 secRecoil in >2 sec
Other things to be looked (not in IMCI guidelines)   
Respiratory rateNormalNormal; fastDeep
Heart rateNormalNormal or increasedIncreased or decreased when most severe
Pulse volumeNormalNormal or decreasedWeak/impalpable
CRTNormalProlongedProlonged, minimal
Anterior fontanelleNormalDepressedDepressed
ExtremitiesWarmCoolCool, mottled, cyanotic
Urine outputNormal to decreasedDecreasedMinimal


  1. Diarrhea – Onset, duration, frequency, pattern, severity
  2. Dysentery – Blood/mucus?
  3. Osmotic vs secretory – fasting reduces stooling amount (osmotic)?
  4. Small bowel vs large bowel diarrhea?
  5. Associations –
    • Gastrointestinal: nausea, vomiting, anorexia, abdominal pain
    • Respiratory tract infection: fever, cough, coryza
    • Arthralgia/arthritis and rash
  6. Recent family history or contact history
  7. Underlying disease, recent infections, medications, HIV
  8. Incubation period: shorter in toxigenic than inflammatory diarrhea
  9. Temporal relation with food

acute diarrhea etiology

 Small bowel diarrheaLarge bowel diarrhea
StoolLarge volume, wateryFrequent, small volume
Associated featuresAbdominal cramps, bloating, gasGripping pain in lower abdomen
FeverNot commonCommon
Blood or mucus in stoolAbsentPresent


  1. Assess for severity of dehydration
  2. Abdominal tenderness/mass? Peritoneal signs?
  3. Perianal inspection: Rash? Ulcer? Active bleeding?
  4. Stool if present: Blood? Mucus?
  5. Extraintestinal signs: Rash? Hepatosplenomegaly? Lymphadenopathy? Arthritis?
  6. Hypokalemia: Abdominal distension? Muscle strength and reflexes?


1. Serum electrolytes (Volume depletion)

2. BUN and serum creatinine:

  • Significant rise in BUN with relatively normal creatinine suggests dehydration
  • If RFT is markedly deranged: screen for HUS, including coagulation studies and markers of hemolysis (LDH, Peripheral blood smear, Haptoglobin)

3. CBC with differential count:

  • Infection: Abnormal WBC or differential count
  • Dehydration: Increased hematocrit
  • HUS: Anemia and thrombocytopenia

Risk factors for bacterial etiology:

  1. Age <6 months
  2. Immunocompromised
  3. Weight <8 kg
  4. Severe (>5 episodes/24 hour)
  5. History of prematurity
  6. Bloody diarrhea
  7. Fevere
  8. Moderate to severe dehydration
  9. Failed ORS therapy
  10. Nonbloody to bloody diarrhea within 5 days of onset
  11. Abdominal pain and tenderness
  12. Pain worse with defecation (especially E.Coli O157:H7)
  13. Rectal prolapse (Shigellosis and E.Coli O157:H7)
  14. Minimal vomiting
  15. Recent antibiotic use

Vomiting and respiratory symptoms are common in viral etiology of acute diarrhea.

Lab investigations for supsected bacterial etiology:

  1. Stool culture including E.Coli O157:H7, C.difficile assay, Giardia, Cryptosporidia assay
  2. Fecal WBC
  3. Consider:
    • Fecal occult blood
    • Blood culture
    • Urine culture
    • Abdominal X-ray


  1. Inability to care or return if necessary
  2. Intractable vomiting
  3. Inadequate ORS intake because of refussal
  4. Lack of improvement
  5. Co-morbid illness
  6. Severe dehydration
  7. Other risk factors


ORS acute diarrhea

Plan A: No signs of dehydration (Mild dehydration)

  1. Treat at home
  2. ORS per each loose stool:
    • <24 months (with Tea spoon): 50-100 ml
    • 2-10 years (Cup sips): 100-200 ml
    • >10 years (Cup sips): Ad lib
  3. Teach ORS preparation
  4. If vomiting: wait 10 minutes and feed slowly
  5. If ORS packet used up, give other fluids

Plan B: Some signs of dehydration (Moderate dehydration)

  1. Treat at home or hospital
  2. Provide daily requirement
  3. Replace deficit:
    • ORS 75 ml/kg over 4 hours OR by NG tube
    • Assess after 4 hours:
      • If still “some signs of dehydration”: Continue deficit replacement
      • If improved to “no signs of dehydration”: ORS 10 ml/kg per stool

Plan C: Severe dehydration

  1. Treat at hospital
  2. Intravenous Ringer Lactate:
    • For <12 months:
      • 1st hour: 30 ml/kg (repeat if feeble pulse)
      • Next 5 hours: 70 ml/kg
    • For >12 months:
      • 1st 1/2 hour: 30 ml/kg
      • Next 2 and 1/2 hours: 70 ml/kg
    • OR NG feeding 20 ml/kg/hr until IV opened
  3. Reassess every 15-30 minutes
  4. Shift plan of treatment according to improvement or continue same treatment

Dehydration at tertiary centers can be treated as following:

1. Stabilization: Bolus 20 ml/kg upto 3 times

2. Deficit replacement: According to the severity of dehydration

3. Maintenance fluid: (Daily requirement* – Bolus amount) over 24 hours

  • Half of total in 1st 8 hours
  • Other half in next 16 hours

Daily requirement* = 4 ml/kg/hr for 1st 10 kg + 2 ml/kg/hr for next 10 kg body weight + 1 ml/kg/hr for subsequent body weight

Causes of ORS failure:

  1. High purge rate >5 ml/kg/hr
  2. Persistent vomiting >3/hr
  3. Paralytic ileus
  4. Incorrect ORS preparation

Content of ORS:

  1. Glucose 13.5 gm/L
  2. Na+ 2.6 gm/L
  3. K+ 1.5 gm/L
  4. Citrate 2.9 gm/L

Total osmolarity: 245 mmol/L


1. Antibiotics: Antibiotic therapy is usually not indicated because illnesses are often self-limited. Indications for antibiotic therapy are:

  1. Shigella, Enterotoxigenic E.Coli, Enteroinvasive E.Coli, Salmonella typhi, Vibrio cholera
  2. Extraintestinal infections (including sepsis) and complications
  3. Infants (<3 months)

Antibiotics for uncomplicated Salmonella is contraindicated as it may prolong the “carrier-state”.

Antibiotics used are:

  • C.difficile: Metronidazole 7.5 mg/kg Or Vancomycin 10 mg/kg
  • Shigella: Azithromycin 10 mg/kg/day Or Ceftriaxone 50 mg/kg/day X 3 days
  • Salmonella: Ceftriazone 100 mg/kg/day BD Or Azithromycin 20 mg/kg/day X 7 days
  • E.Coli O157:H7: None
  • Enteroinvasive E.Coli: As shigella
  • V.Cholera: Erythromycin 30 mg/kg/day divided TID OR Azithromycin 10 mg/kg/day X 3 Days
  • Giardiasis: Metronidazole 15 mg/kg TDS X 5-7 days OR Tinidazole 50 mg/kg PO once (max 2 gm) OR Nitazoxanide
  • Cryptosporidium: Nitazoxanide
  • ETEC, EAEC, Traveller’s diarrhea: Azithromycin or Ceftriaxone X 3 days

2. Antidiarrheals: not recommended because it may cause abdominal distension and bacterial overgrowth

3. Zinc supplementation: 20 mg Elemental Zinc/day for child >6 months X 14 days

4. Ondansetron: 0.1-0.2 mg/kg/dose

5. Potassium (if patient is passing urine): KCl 30-40 mEq/L

6. Antisecretory (inhibit intestinal enkephalinase): Racecadotril

7. Probiotics: contains Lactobacillus rhamnosus, Enterococcus fecium, Saccharomyces boulardii

8. Vaccine: Rotavirus


  1. Avoid simple sugar foods (Carbonated beaverages, commercial fruit juices, sweetened tea)
  2. Early feeding reduces infection induced permeability
  3. BRAT (Banana, Rice, Apple sauce, Toast) are overly restrictive and increases recovery time
  4. Age appropriate unrestricted diet must be given – complex carbohydrates, meats, yoghurt, fruits, vegetables

7 Basic principles of Management of Acute Diarrhea:

  1. Give ORS when possible
  2. ORS must be started within 3-4 hours
  3. Age appropriate unrestricted diet must be given after dehydration correction
  4. Continue breastfeeding
  5. Diluted formula is not recommended
  6. Replace ongoing losses with ORS
  7. Minimize unnecessary lab investigation/medication

Write your Viewpoint đź’¬

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.