Pediatric Gastroenteritis in Emergency Medicine Workup

Updated: Jan 17, 2023
  • Author: Adam C Levine, MD, MPH; Chief Editor: Kirsten A Bechtel, MD  more...
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Laboratory Studies

The vast majority of children presenting with acute gastroenteritis do not require serum or urine tests, as they are unlikely to be helpful in determining the degree of dehydration. In a meta-analysis of 6 studies, only serum bicarbonate (< 17) had statistically significant positive and negative likelihood ratios for detecting moderate dehydration. [29]  Serum bicarbonate is also most closely associated (inversely) with the clinical dehydration scale (CDS) score out of all the tested urine biomarkers. [30]                                                                                                                   

Clinically significant electrolyte abnormalities are rare in children with moderate dehydration. However, any child being treated with intravenous fluids for severe dehydration should have baseline electrolytes, bicarbonate, and urea/creatinine drawn. Laboratory tests are also indicated in patients with moderate dehydration whose history and physical examination are inconsistent with straightforward gastroenteritis.

Fecal leukocytes and stool culture may be helpful in children presenting with bloody diarrhea or recent travel to a low-resource setting. Children older than 12 months of age with a recent history of antibiotic use should have stool tested for C difficile toxins. Those with a history of prolonged watery diarrhea (>14 d) or travel to an endemic area should have stool sent for ova and parasites.

Any child with evidence of systemic infection should have a complete workup, including complete blood count (CBC) and blood cultures. If indicated, urine cultures, chest radiography, and/or lumbar puncture should be performed.


Imaging Studies

Abdominal films are not indicated in the management of acute gastroenteritis. If the clinician suspects a diagnosis other than acute gastroenteritis based on history and physical examination findings, appropriate imaging modalities should be pursued.

A study looked to determine the predictive value of ultrasonography for appendicitis in children when combined with clinical assessment based on the Pediatric Appendicitis Score (PAS). The study concluded that ultrasound findings in children with possible appendicitis should be integrated with clinical assessment, such as a clinical score, to determine next steps in management. Rates of false-negative ultrasonography increase with increasing PAS, and false-positive ultrasonography results occur more often with lower PAS. When discordance exists between ultrasonography results and the clinical assessment, serial examinations or further imaging are warranted. [31]  As US sensitivity is limited, non-visualization of the appendix and non-diagnostic US results can be followed by clinical reassessment and complementary imaging with MRI/CT. [32]

Corrected carotid flow time was found to be a poor predictor of severe dehydration (those with hypovolemia) in a prospective cohort study that enrolled a sample of 350 children age 0-60 months presented with acute diarrhea in Bangladesh. [33]  This finding contrasts with previous studies that found this tool to be effective in predicting volume status and fluid responsiveness in adults. [33]

Ultrasound of the inferior vena cava to aorta ratio has been shown to be associated with overall volume status in children, a recent large study did not find it sensitive or specific enough to use as an independent tool for the diagnosis of dehydration in children with diarrhea. [34]   A meta-analysis found that beside ultrasound may help in ruling out dehydration but should not be used to confirm the presence of dehydration. In addition, current evidence does not support the routine use of ultrasound or urinalysis to determine dehydration severity. [35]


Other Tests

Workup of acute gastroenteritis should begin by using elements of the history and physical examination to determine level of dehydration. Both the Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP) recommend using a simple dehydration scale to classify the total body water loss occurring with dehydration as minimal/none (< 3%), mild/moderate (3-9%), or severe (>10%) (see Table 1 below). [8] The World Health Organization (WHO) recommends a simpler system for use by both physicians and lay health workers, which classifies dehydration as none, some, or severe.

Studies have found that combinations of clinical signs, symptoms, diagnostic tools and laboratory test may have better sensitivity and specificity for detecting dehydration in children than individual signs or symptoms. [35, 36]             

The golden standard to detect the level of dehydration in children remains the percentage change between pre-illness weight and admission weight. However, pre-illness weight is rarely available in limited-resource settings. There are standardized scales that can assist in evaluating dehydration and their efficacy is discussed below. The four scales are the WHO algorithms, the Gorelick scale, the Clinical Dehydration Scale (CDS), and finally the DHAKA score.   

A review of the first three clinical prediction models by Freedman et al found that the CDS and Gorelick scales consistently reported sensitivity of more than 80% in identifying dehydration in high-income countries, though acknowledges that at least one study by Jauregui, et al (2014) reported lower values. [2, 37] The authors conclude that the scales provide some improved diagnostic accuracy, but substantial gap remains in how well the scores predict the outcome of interest. Future research should focus on clarifying the efficacy of the existing dehydration assessment tools, especially the WHO algorithm because of its international usage, and develop new tools, especially those that can be used in low-resourced settings, with greater accuracy.          

The Dehydration: Assessing Kids Accurately (DHAKA) scale is a newly developed tool. The DHAKA Dehydration Score comprises of 4 clinical signs: general appearance, skin pinch, tears, and respiration. The DHAKA Score has been internally and externally validated and concluded to be statistically more accurate and reliable than the WHO algorithm when used in children with acute diarrhoea in a low-income country. [38]

One potential obstacle to the accurate assessment of dehydration status is acute malnutrition. The WHO cites difficulty in using clinical signs alone to assess the dehydration status in severely malnourished children because there is a  potential for the clinical signs to be distorted by malnutrition. However, one study found that, contrary to this recommendation, clinical signs of dehydration are as accurate in children with acute malnutrition as in children without acute malnutrition. [39] However, children with bilateral pitting edema (3.8% children) was excluded from the study. In addition, acute malnutrition did not have a significant effect on the accuracy of the DHAKA score, the WHO scale, or the CDS to predict any dehydration.

Table 1. Assessment of Dehydration* (Open Table in a new window)

Symptom or Sign

No or Minimal Dehydration

Mild to Moderate Dehydration

Severe Dehydration

Mental status


Restless, irritable

Lethargic, unconscious


Drinks normally

Drinks eagerly

Drinks poorly

Heart rate


Normal to increased


Quality of pulses


Normal to decreased

Weak or impalpable



Normal or fast




Slightly sunken

Deeply sunken





Mouth and tongue




Skin fold

Instant recoil

Recoil < 2 seconds

Recoil >2 seconds

Capillary refill



Prolonged or minimal




Cold, mottled, cyanotic

Urine output




*Adapted from King et al. MMWR Recomm Rep. 2003;52(RR-16):1-16. [6]

  Table 2. Assessment of Dehydration According to the World Health Organization* (Open Table in a new window)

Severe Dehydration

Two of the following signs:

-Lethargic or unconscious

-Sunken eyes

-Not able to drink or drinking poorly

-Skin pinch goes back very slowly

Some Dehydration

Two of the following signs:

-Restless, irritable

-Sunken eyes

-Thirsty, drinks eagerly

-Skin pinch goes back slowly

No Dehydration

Not enough of the above signs to classify as some or severe dehydration

*Adapted from World Health Organization. [7]


Table 3:

Clinical Dehydration Scale (Open Table in a new window)

General Appearance Normal Thirsty, restless, or irritable Lethargic or unconscious
Eyes Normal Slightly sunken Very sunken
Mucous Membranes Moist Dry Very dry
Tears Tears present Decreased tears Absent tears

Adapted from Parkin PC, Macarthur C, Khambalia A, Goldman RD, Friedman JN. Clinical and laboratory assessment of dehydration severity in children with acute gastroenteritis. Clin Pediatr (Phila). 2010 Mar;49(3):235–9.


Dehydration: Assessing Kids Accurately (DHAKA) Score (Open Table in a new window)

Clinical Sign Finding Points
General Appearance Normal 0
Restless/irritable 2
Lethargic/unconscious 4
Tears Normal 0
Decreased 1
Absent 2
Skin Pinch Normal 0
Slow 2
Very slow 4
Respirations Normal 0
Deep 2

Total: ≥4 severe dehydration, 2-3 some dehydration, 0-1 no dehydration

Adapted from: External Validation of the DHAKA score and comparison to the current IMCI algorithm for the assessment of dehydration in children with diarrhoea. Lancet Global Health. 2016 Oct;4(10):e744-51.