Pediatric gastrointestinal disturbances are common, often simple to manage and yet, unfortunately, life-threatening in some instances. Sometimes, seemingly innocuous vomiting can be a harbinger of a serious underlying disease. This article expounds on various pathophysiological aspects of pediatric vomiting and diarrhea and expatiates on the rapid aggressive treatment of accompanying dehydration.
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Pediatric Vomiting

Vomiting is a symptom rather than a diagnosis. It can be secondary to gastrointestinal causes or rarely secondary to distant organ system such as vomiting secondary to increased intracranial pressure. The whole symptom constellation with associated complaints and examination findings aided by a meticulous history is often crucial in the correct interpretation of vomiting and its subsequent treatment.

Various etiologies leading to vomiting can be segregated as per age of the child:

Age Possible cause
Infants To be distinguished from regurgitation – spontaneous expulsion of gastric contents. Possible differentials for vomiting comprise of gastroenteritis, GERD, food allergy, milk protein intolerance, overfeeding, an inborn error of metabolism.
Neonates GI obstruction related to congenital malformation, sepsis, sinusitis and otitis media.
Children, adolescents Gastroenteritis, systemic infections, toxic ingestions, appendicitis, ulcers, pancreatitis, migraine, medications, pregnancy, Intracranial pathology, otitis media.

Another way of classifying vomiting is according to the responsible system; the same is tabulated below:

System Cause
Metabolic Inborn errors of metabolism, urea cycle disorders
Intoxication Medication, aspirin
Endocrine DKA, Addisonian crisis
Sepsis Pneumonia, otitis media, meningitis, UTI
Intracranial disease Brain tumors, hydrocephalus, raised intracranial pressure
Gastro-intestinal Infection: appendicitis, hepatitis, pancreatitis, gastroenteritis

Motility disorders: pyloric stenosis, achalasia

Inflammation: GERD, duodenal ulcers, food allergy

Anatomical obstruction: intestinal malrotation, volvulus, intussusception, obstructed a hernia


Vomiting is a vagal mediated reflex and actually a protective mechanism. It is mediated by peripheral receptors and central controlling units. The central processing units are situated in the medulla near the obex of the fourth ventricle.

Vomiting is composed of nausea, retching and conscious expulsion of gastrointestinal contents. It is a culmination of synchronized contraction of intercostals muscles, diaphragm and abdominal muscles with the sequential relaxation of the esophageal sphincter.

Diagnosis of Pediatric Vomiting

Vomiting is a symptom and a potential harbinger of an underlying serious disorder.

Extensive history taking, followed by a relevant clinical examination, can often narrow down the system involved.

Salient points to be essentially covered in history are:

  • Demographic details of the patient: age, sex, place of residence (important in cases of epidemics and food poisoning)
  • Onset/duration/progress of complaints
  • Association of food intake
  • Any other associated complaints: fever, earache, headache, abdominal pain, dysphagia
  • Review of systems, past medical and surgical history, drug intake, drug allergy, social and nutritional history
  • Nature of the vomitus (projectile/non-projectile), color, contents, painful/painless

Color and content of vomitus are often of crucial significance. A rough estimate of the level of obstruction can be discerned based on these findings alone as follows:

Nature of vomitus Approximate level of obstruction
Non-bilious acidic vomitus Distal to stomach, proximal to duodenum
Bilious vomiting Distal to 2nd part of duodenum
Feculent vomitus Obstruction in the large bowel
Non-digested food content Proximal obstruction

History should aid in performing localized relevant examination.

It is of paramount importance to assess hydration status in every pediatric patient with vomiting. The red-flag signs of dehydration should usher emergent, rapid, aggressive fluid management. These are documented as follows:

  • Reduced skin turgor
  • Sunken eyes, often tearless
  • Dry mucous membranes
  • Sunken fontanelle
  • Tachycardia, tachypnea
  • Prolonged capillary refill time


The list of differentials formed at the end of clinical assessment help guide the investigations to be performed. Some frequent investigations and their relevance are:

Investigation Relevance
Complete blood count To look for leucocytosis in case of infections
Serum creatinine and electrolytes Assess hydration, potential electrolyte imbalance after vomiting, renal function
Blood glucose level In DKA
Blood gases In inborn errors of metabolism,
Imaging Abdominal imaging: X-ray, ultrasonography, CT abdomen with pelvis, endoscopy as per the etiology

Brain imaging: if intracranial etiology is suspected.

Treatment of Pediatric Vomiting

Once the cause is identified, there are two phases of management of vomiting – namely to resuscitate and stabilize the patient in an emergent manner with subsequent treatment of the inciting factor.

Strategy Explanation
Assess hydration status Hydration is the most important step in the resuscitation of a pediatric patient. Well-established protocols are available based on age, the weight of the patient and customized therapy can be initiated. Regular monitoring is a must. While oral intake is desirable, one should use intravenous resuscitation when deemed necessary.
Check for electrolyte imbalance Vomiting is associated with an electrolyte imbalance which can occasionally turn symptomatic. A careful assessment of a patient’s hydration and electrolytes with the simultaneous management of the same is the key.
Treat underlying etiology Definitive treatment of the underlying condition is the ultimate treatment.

Pediatric Diarrhea

The normal frequency of bowel movement is about thrice daily up to alternate daily. Excess of daily stool volume of more than 10 ml/kg/body weight per day is an objective definition of diarrhea.

The working definition involves liquid consistency, increased frequency and increased volume of stools. Twice the normal frequency of motions for an infant and more than three liquid stools per day in older children is considered abnormal.

These definitions are rather to be used precariously, always taking into account the age, diet, and weight of the child.

The presence of certain substances in stools is never normal and should initiate appropriate workup and subsequent management. These are:

  • Mucus
  • Fresh blood – red
  • Altered blood – black
  • Foul smell
  • Runny, watery stools

Certain subsets of the pediatric population are more prone to develop diarrhea. The relevant significant ones are:

  • Lack of breastfeeding
  • Malnutrition
  • Measles
  • Attendance to childcare centers
  • Exposure to unhygienic circumstances
  • Poor maternal education
  • Immunodeficient individuals


Pediatric diarrhea can be classified as variously as follows:

Based on temporal relation:

  • Acute: for less than 14 days
  • Chronic/persistent: for more than 14 days

Based on mechanism:

  • Osmotic: stool volume depends on diet and decreases with fasting
  • Secretary: stool volume is increased and does not vary with diet
  • Motility disturbance: often diagnosed in older children
  • Mucosal inflammation: secondary to invasive bacteria and inflammatory bowel disease
  • Mixed secretary-osmotic: seen in infections like Rotavirus

Based on clinical features:

  • Acute watery diarrhea:
    • Most common, usually self-limiting. The most crucial concern is the maintenance of hydration status.
    • Rota-virus, Vibro cholerae
  • Acute bloody diarrhea:
    • Also known as dysentery; the culmination of intestinal mucosal erosion by invasive species. The most significant complications are sepsis, HUS (Hemolytic Uremic Syndrome), malnutrition and dehydration.
    • Entamoeba histolytica, Shigella species.

Based on etiology:

  • Infectious: secondary to infection
  • Mal-absorptive: increased stool output with an excess of fluid and electrolytes

Infectious Diarrhea

Viral infectious diarrhea is the most prevalent pediatric diarrhea. Pyogenic follows next in line. The key to diagnosis is to recover the organism in stools. Enzyme immunoassay is helpful in some cases.

A short summary of infectious diarrhea is presented below:

Infectious agent Diarrhea-key points Treatment
Viral etiology
Rotavirus Most common viral diarrhea; prevalent during winter. Most common cause of watery diarrhea; lasts for 7-10 days. It may be associated with vomiting. Symptomatic management; maintain hydration
Norwalk virus Prevalent in cruise ships Symptomatic management; maintain hydration
Bacterial etiology
E. coli Enteropathogenic E.coli is responsible for breakouts in nurseries and daycare.
Salmonella Salmonella reaches pediatric population through eggs, milk, poultry, and reptiles. Antibiotics indicated only for age < 3 months, toxic state and disseminated disease. Trimethoprim/sulfamethoxazole is typically used, but it prolongs carrier state.
Shigella Transmitted through contaminated food; Shigella can cause seizures. Trimethoprim/sulfamethoxazole is the first choice.
Campylobacter Transmitted by contaminated food. Antibiotics for severe disease, erythromycin is the drug of choice.
Yersinia Transmitted by pets, contaminated food, may be associated with arthritis and rash (often confused with Inflammatory Bowel Disease, pseudo-appendicitis) Antibiotics for < 3 months of age and septicemia. Aminoglycosides or third-generation cephalosporins are recommended.
S. aureus Onset within 12 hours of ingestion, toxin-mediated. Penicillin and third-generation Cephalosporin work; for resistant species; Vancomycin is advocated.
Clostridium History of preceding heavy antibiotic use usually prevails. Oral Metronidazole or Vancomycin is used.
Parasitic etiology
Entamoeba histolytica, Giardiasis, Cryptosporidium Metronidazole is typically recommended as the drug of choice.

Diagnosis of Pediatric Diarrhea

Diarrhea is deceptive and not always innocuous and benign in nature. Constant vigilance and prevention of dehydration is a must. Correct, timely diagnosis is the key.

The diagnostic strategy begins with expert history taking and performing a relevant clinical examination.

The relevant key points to be focused upon in history are as follows:

  • Demographics of the child
  • Onset, duration, progress of diarrhea
  • Nature, content, color, smell, consistency, frequency of stools
  • Presence of blood, worms, mucus, foreign body in the stools
  • Associated complaints: fever, abdominal pain, earache, history of measles, vaccination, convulsions
  • Treatment history

The relevant physical examination can then be carried out in the right perspective as suggested by a focused history is very helpful.  The assessment of hydration status forms the heart of a physical examination in pediatric diarrhea.

In children, the signs and symptoms of dehydration are not always loud and clear. A simplified grading of dehydration status based on clinical acumen is as follows:

Degree of dehydration
Clinical feature Less than 3% loss of body weight (NO DEHYDRATION) 3-9% loss of body weight (SOME DEHYDRATION) More than 9% loss of body weight (SEVERE DEHYDRATION)
Eyes Normal Mildly sunken Deeply sunken
Tears Adequate Decreased Absent
Tongue Moist Dry Parch dry
Skinfold Supple with instant recoil when pinched Recoil in less than 2 seconds Recoil in more than 2 seconds
Mental status Normal Normal or fatigues; may be restless and irritable Lethargic, apathetic, drowsy or sometimes frankly unconscious
Thirst Normal Thirsty and looks forward to fluids Unable to drink
Heart rate Normal Normal to increased Increased; bradycardia may be encountered in severe cases
Extremities Warm Cold Cold, cyanotic and mottled
Urine output Adequate; or slightly decreased. Decreased Grossly decreased
Capillary refill Normal Prolonged Prolonged with little refill

Assessment and subsequent desired treatment of dehydration is the most significant life-saving act that medical personnel is expected to perform in the management of pediatric diarrhea.


Ancillary tests are often helpful in reaching the correct diagnosis, but they do not bring about a drastic change in the acute management of pediatric diarrhea. They are definitely relevant in the long run to know the exact etiology and rule out predisposing factors, if any.

These tests can be summarized as follows:

Routine blood investigations The complete blood count is adjunct to confirming infectious etiology. Renal function tests and electrolytes are helpful in the assessment of hydration status.
Stool microscopy and culture The following points are noted:

Presence of blood, ova, cysts or trophozoites

Leucocyte count (more than 10 per HPF) is indicative of invasive diarrhea.

For chronic diarrhea, stool cultures are obtained.

Imaging Ultrasonography, endoscopy are mostly reserved for patients with chronic diarrhea.
Serum enzyme assays Increasing a number of specific biochemical enzyme assays is available to accurately pinpoint the cause of diarrhea.

Treatment of Pediatric Diarrhea

It is worth reiterating that the acute management of diarrhea revolves around the emergent maintenance of hydration status. The long-term management consists of the determination of the cause, inciting factors and correction of the same to prevent a relapse.

The treatment strategy is summarized as follows:

Acute fluid management Rapid recognition of dehydration and treatment of the same is very important. Oral rehydration therapy is typically used. In infants and neonates, the continuation of breastfeeding is strongly recommended.
Zinc Zinc is advocated by WHO, especially for children in developing countries as its deficiency is associated with impaired cellular and humeral immunity and dysregulated electrolyte balance. Zinc supplementation reduces morbidity associated with pediatric diarrhea.
Probiotics Probiotics strengthen the mucosal immune response and consolidate the tight junctions between the enterocytes. Competitive inhibition of binding of pathogens to the bowel mucosa is often instrumental
Prevention Hand washing post defecation and prior to the consumption of food can halve the burden of infectious diarrhea.
Drug therapy Antibiotics are to be used only in very small children and in patients with systemic infliction. The use of drugs like anti-motility and anti-secretory agents is rather condemned in a pediatric set-up.


  • Vomiting by itself is more of a symptom than a diagnosis. Meticulous history taking and a relevant physical exam with pertinent ancillary tests performed help in making the right diagnosis. Treatment follows accordingly.
  • Pediatric diarrhea can be variously classified based on etiology, mechanism, and temporal relation.
  • The key factor in the treatment of both pediatric vomiting and diarrhea is the maintenance of the hydration status.
  • Long-term management consists of the evaluation of the inciting factor, treatment of the same and corrective steps taken to avoid relapses.

Review Questions

The correct answers can be found below the references.

1. Which of the following statements is false?

  1. Otitis media can cause vomiting.
  2. Meticulous history taking and the relevant physical exam is the key to making the correct diagnosis of vomiting.
  3. Projectile non-bilious vomiting can be caused by pyloric stenosis.
  4. Zinc is detrimental and should be avoided in children with diarrhea.

2. Which of the following infectious agent causes diarrhea with convulsions?

  1. E.coli
  2. Salmonella
  3. Shigella
  4. Yersinia

3. Which of the following signs indicate severe dehydration?

  1. Deeply sunken eyes, minimal capillary refill
  2. A thirsty child with a normal pulse rate
  3. Vomiting child with easy skin recoil
  4. Tachycardia with normal urine output
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