CCS Integrated Cases

CCS case: pediatric dehydration from gastroenteritis

Clinical Overview and When to Suspect Pediatric Dehydration from Gastroenteritis

— ≥3 watery stools/day or repeated vomiting AND decreased intake

— Decreased urine output (<1 wet diaper per 8 h in infants, no urine ≥8 h in older children)

— Lethargy, irritability, sunken eyes, tachycardia, or weight loss vs. recent well-child weight

— Mild: 3–5% (infants up to 5%); minimal signs

— Moderate: 6–9% (infants up to 10%); tachycardia, dry mucosa, delayed cap refill 2–3 s

— Severe: ≥10% infants / ≥9% children; shock, altered mental status, cap refill >3 s, anuria

— Age <6 months or weight <8 kg

— Prematurity, chronic illness, immunocompromise

— ≥8 stools/24 h or ≥4 vomits/24 h

— Inability to tolerate oral rehydration at home

— Caregiver unable to monitor reliably

Acute gastroenteritis (AGE) is the most common cause of dehydration in US children under 5; viral pathogens dominate (norovirus #1 overall, rotavirus declining post-vaccine, sapovirus, adenovirus 40/41, astrovirus).

Bacterial causes (Salmonella, Shigella, Campylobacter, STEC O157:H7, C. difficile) and parasitic (Giardia, Cryptosporidium) are minority but exam-favorite when bloody stools, prolonged fever, or daycare/travel/animal exposure cues appear.

Suspect clinically significant dehydration when a child has:

Severity by % weight loss (gold standard if pre-illness weight known):

High-risk subgroups that lower your threshold to admit or treat aggressively:

Board pearl: The single most accurate bedside predictor of ≥5% dehydration is a combination of prolonged capillary refill (>2 s), abnormal skin turgor, and abnormal respiratory pattern—not isolated dry mucous membranes or sunken fontanelle. Memorize the Gorelick 4-sign / 10-sign scales and the WHO/CDC severity table; CCS cases reward early severity classification because it dictates ORT vs. IV bolus pathway.

Presentation Patterns and Key History

— Bloody/mucoid diarrhea → Shigella, Salmonella, Campylobacter, STEC, Entamoeba, or IBD

— High fever >39°C with seizures → Shigella (neurotoxin), can occur before diarrhea

— Diarrhea after antibiotics → C. difficile (test only if ≥12 months; colonization common <1 yr)

— Recent fast food / ground beef / petting zoo → STEC → watch for HUS day 5–10

— Daycare outbreak, no fever, vomiting predominant → norovirus

— Persistent diarrhea >14 days, foul greasy stools, weight loss → Giardia, post-infectious lactase deficiency

— Onset, frequency, volume, character of stools and emesis (bilious? bloody? projectile?)

— Last urine output / wet diaper count

— Oral intake (type, volume, ORS attempted?)

— Pre-illness weight (compare to today)

— Fever, rash, mental status changes

— Sick contacts, daycare, travel, well/untreated water, animal exposure

— Immunization status, esp. rotavirus series (completed by 8 months)

— Medications, recent antibiotics, antimotility/herbal agents

— Underlying illness, immune status, prior surgeries (short gut?)

Typical viral AGE prodrome: 12–48 h incubation → low-grade fever and vomiting first, followed by watery non-bloody diarrhea; symptoms resolve in 3–7 days. Norovirus skews toward prominent vomiting; rotavirus toward profuse watery diarrhea in unvaccinated infants 6–24 months.

Red-flag patterns suggesting non-viral or alternative dx:

Key history checklist to elicit on CCS:

Key distinction: Bilious emesis in an infant is gastroenteritis until proven otherwise—but you must exclude malrotation with midgut volvulus first with an urgent upper GI series. Likewise, projectile non-bilious emesis in a 3–6 week-old male = pyloric stenosis, not AGE. CCS will plant these as distractors; ordering the right initial imaging is what scores points.

Board pearl: Vomiting without diarrhea in a febrile child should trigger consideration of UTI, otitis, pneumonia, DKA, intussusception (currant-jelly stool later), and increased ICP—not AGE.

Physical Exam Findings and Hemodynamic Assessment

— HR (tachycardia is the earliest sign of volume loss in children; hypotension is LATE and ominous)

— RR (tachypnea from metabolic acidosis—Kussmaul-like)

— BP (use age-appropriate cuff; hypotension = decompensated shock)

— Temp, SpO2, weight in kg (compare to baseline)

— General/mental status: alert, irritable but consolable, lethargic, obtunded

— HEENT: anterior fontanelle (sunken in infants <18 mo), sunken eyes, absent tears in crying child, dry/tacky/parched mucous membranes

— Cardiovascular: capillary refill (central—sternum—is most reliable), pulse quality (thready in shock), extremity temperature, mottling

— Skin: turgor (tent on abdomen >2 s = significant loss), elasticity

— Respiratory: deep/labored breathing suggests acidosis

— Abdomen: soft, mild diffuse tenderness expected; localized peritonitis, mass, or absent bowel sounds → reconsider dx (appendicitis, intussusception, volvulus, HUS)

— Perianal: excoriation common; rectal exam if bloody stool to confirm

— 0 = none, 1–4 = some, 5–8 = moderate/severe

Vital signs first—every CCS pediatric AGE case:

Targeted exam by system:

Clinical Dehydration Scale (CDS, 0–8): general appearance, eyes, mucous membranes, tears

Shock recognition triad in kids: tachycardia + delayed cap refill + altered mental status. Hypotension defines decompensated shock and demands immediate IV/IO access.

CCS pearl: Document a pre- and post-intervention weight and a focused exam at every reassessment (q1h in moderate, q15min in severe). The grader rewards serial vitals, repeat cap refill, and repeat mental-status checks because they drive the bolus-vs-maintenance decision tree.

Board pearl: Cold, mottled extremities with normal BP in a child = compensated shock. Do not be falsely reassured by a "normal" blood pressure; pediatric BP is the last thing to drop and the first thing to crash.

Diagnostic Workup — Initial Labs, Imaging, and Bedside Tests

— BMP (Na, K, Cl, HCO3, BUN, Cr, glucose): look for hypo/hypernatremia, hypokalemia, non-anion-gap metabolic acidosis (stool HCO3 loss), elevated BUN:Cr, hypoglycemia (common in toddlers who stopped eating)

— Venous blood gas: confirm acidosis, guide resuscitation

— CBC with differential: leukocytosis with left shift in bacterial; schistocytes + thrombocytopenia + ↑Cr = HUS

— Urinalysis: specific gravity >1.025, ketones; rule out UTI as occult cause of vomiting in infants

— Point-of-care glucose in every lethargic child

— Bloody/mucoid diarrhea, fever >39°C, severe abdominal pain

— Immunocompromised, recent travel, daycare outbreak investigation

— Diarrhea >7 days

— Order: stool culture (include STEC/Shiga toxin EIA), stool ova & parasites if travel/persistent, C. difficile PCR only if ≥12 months and risk factors, multiplex GI PCR panel where available

— Do NOT routinely test stool for occult blood or fecal leukocytes—poor performance

— Abdominal XR if obstruction/perforation suspected

— Ultrasound for intussusception (target sign) or pyloric stenosis

— Upper GI series urgently if bilious emesis to exclude malrotation/volvulus

Mild dehydration / clear viral AGE: NO labs needed. Clinical assessment + oral rehydration trial is the standard of care. Over-testing is a common CCS deduction.

Moderate to severe dehydration, or atypical features → order:

Stool studies—indicated when:

Imaging: rarely needed for uncomplicated AGE

Step 3 management: A 2-year-old with moderate dehydration who cannot tolerate ORT gets BMP + glucose + VBG before starting a 20 mL/kg NS bolus, because hypo-/hypernatremia changes your fluid choice and replacement rate. Drawing labs on insertion of the IV saves a stick.

Board pearl: HCO3 <17 mEq/L on BMP correlates with ≥5% dehydration and predicts ORT failure—useful triage threshold.

Diagnostic Workup — Advanced and Confirmatory Studies

— Repeat BMP q4–6h during active IV resuscitation, especially with hyper- or hyponatremia (Na correction rate ≤0.5 mEq/L/h, ≤10–12 mEq/L per 24 h to avoid cerebral edema or central pontine myelinolysis)

— Lactate if shock physiology

— LFTs, lipase if vomiting persists or RUQ/epigastric pain (hepatitis, pancreatitis mimics)

— Blood culture if febrile and toxic-appearing, immunocompromised, or <3 months with fever

— Lumbar puncture if meningitis cannot be excluded in an ill-appearing infant

— Urine culture in any febrile infant <24 months with vomiting/poor feeding

— CBC (anemia, thrombocytopenia <150k), peripheral smear (schistocytes), BMP (↑Cr, ↑K), LDH ↑, haptoglobin ↓, UA (hematuria, proteinuria), Coombs negative

— Avoid antibiotics and antimotility agents in suspected STEC—both increase HUS risk

— Avoid platelet transfusion unless bleeding

— Stool Giardia antigen, Cryptosporidium antigen

— Stool elastase (pancreatic insufficiency), reducing substances & stool pH <5.5 (carbohydrate malabsorption / post-viral lactase deficiency)

— Celiac serology (TTG IgA + total IgA) if introduced to gluten

— Sweat chloride if FTT pattern (CF)

— Abdominal US for intussusception (children 6 mo–3 yr with intermittent inconsolable crying, bilious emesis, or currant-jelly stool); air or saline enema is both diagnostic and therapeutic

— CT abdomen with contrast only if perforation, abscess, or appendicitis

When initial workup is unrevealing or course is atypical, escalate:

HUS workup (STEC-associated, peaks day 5–10 of bloody diarrhea):

Persistent / chronic diarrhea (>14 d):

Imaging escalation:

CCS pearl: A child with bloody diarrhea who develops oliguria on hospital day 3 needs immediate repeat CBC, BMP, LDH, smear, and UA—you are looking for HUS onset. Move the case clock forward in 6-hour intervals and reassess labs; missing HUS is a high-stakes deduction.

Board pearl: Hypernatremic dehydration ("doughy" skin, irritability, seizures on rapid correction) typically arises from improperly mixed formula or boiled-down formula—social/feeding history is the giveaway.

Risk Stratification and First-Line Management Logic

— Continue age-appropriate diet

— Replace ongoing losses: 10 mL/kg per diarrheal stool, 2 mL/kg per emesis using ORS

— Home management with return precautions

— ORS (Pedialyte, WHO-ORS, Enfalyte): 50 mL/kg over 4 h for mild; 100 mL/kg over 4 h for moderate

— Give in small frequent aliquots (5 mL every 1–2 min via syringe/teaspoon) — beats vomiting

— Consider single-dose ondansetron PO (2 mg if 8–15 kg, 4 mg if 15–30 kg, 8 mg if >30 kg) before ORT to reduce vomiting and IV use; improves ORT success and reduces admissions

— Reassess in 1 h, then q2h; if tolerating, transition to maintenance + replacement of ongoing losses

— 20 mL/kg isotonic crystalloid (NS or LR) IV bolus over 15–20 min

— Reassess perfusion; repeat boluses up to 60 mL/kg total

— If no improvement after 60 mL/kg → suspect ongoing losses vs. alternate dx vs. distributive/septic shock → escalate to ICU, consider pressors

— After perfusion restored, transition to D5½NS + 20 mEq/L KCl at maintenance + deficit replacement (½ deficit over first 8 h, remainder over next 16 h) — modified if dysnatremia present

— 4 mL/kg/h for first 10 kg + 2 mL/kg/h for next 10 kg + 1 mL/kg/h for each kg above 20

Management is driven by severity assessment → choose the rehydration route:

Minimal/no dehydration (<3%):

Mild–moderate dehydration (3–9%) — ORT is FIRST LINE per AAP/CDC/WHO:

Severe dehydration (≥10%) or shock — IV/IO route:

Maintenance fluid rate (4-2-1 rule):

CCS pearl: On the CCS interface, the correct sequence in a vomiting, lethargic 18-month-old with cap refill 4 s is: IV access → 20 mL/kg NS bolus → BMP/glucose/VBG → reassess at 20 min → repeat bolus PRN → start maintenance D5½NS + KCl once urinating. Order ondansetron only after vomiting persists despite rehydration.

Board pearl: Do not use plain water, juice, soda, or sports drinks for rehydration—wrong osmolality and sugar content worsen diarrhea (osmotic load) and risk hyponatremia.

Pharmacotherapy — First-Line Drug Regimens

— Dose: PO ODT 2 mg (8–15 kg), 4 mg (15–30 kg), 8 mg (>30 kg); IV 0.15 mg/kg

— Single dose to facilitate ORT; reduces vomiting, IV placement, hospitalization

— Side effects: mild diarrhea (paradoxical), QT prolongation (rare at single dose); avoid in congenital long QT

— Avoid promethazine, prochlorperazine, metoclopramide in young children (extrapyramidal, sedation, black-box <2 yr for promethazine)

— Loperamide: contraindicated <3 years; risk of ileus, toxic megacolon in invasive bacterial; not recommended routinely

— Bismuth subsalicylate: salicylate exposure → Reye syndrome concern; not recommended

— Antidiarrheals are CONTRAINDICATED in suspected STEC or C. difficile

— Shigella (severe or dysentery): azithromycin 10 mg/kg/day × 3 days (resistance rising); ceftriaxone alternative

— Campylobacter (severe/prolonged): azithromycin × 3 days

— Salmonella (non-typhoidal): treat only if <3 months, immunocompromised, bacteremic, or severe; ceftriaxone. Otherwise treatment prolongs carriage

— C. difficile: oral vancomycin or fidaxomicin (metronidazole only if mild and alternatives unavailable)

— Giardia: tinidazole single dose (≥3 yr) or nitazoxanide; metronidazole alternative

— STEC O157:H7: NO antibiotics — increases HUS risk

Ondansetron (5-HT3 antagonist) — the only antiemetic with pediatric AGE evidence:

Antidiarrheals — generally avoided:

Antibiotics — only for specific pathogens/situations:

Probiotics: AAP no longer routinely recommends; modest evidence for Lactobacillus rhamnosus GG or S. boulardii to reduce diarrhea duration by ~1 day; not first-line.

Zinc supplementation: WHO recommends 10–20 mg/day × 10–14 d for children in low-resource settings; not standard in US.

Step 3 management: A 4-year-old with 3 days of bloody diarrhea after a picnic—send stool culture with Shiga toxin, hold antibiotics, hold loperamide, hydrate IV, monitor CBC/Cr/UA daily for HUS. Empiric ciprofloxacin is the wrong answer.

Board pearl: Single-dose ondansetron is the highest-yield drug in pediatric AGE CCS cases—it converts an IV admission into a discharge.

Procedures and Invasive Management

— Two attempts × 90 seconds each in severe dehydration; if unsuccessful → intraosseous (IO) access in proximal tibia (or distal femur, proximal humerus)

— IO is acceptable for all resuscitation fluids, medications, and blood products in pediatrics

— Transition to peripheral IV or central line once stabilized

— Indicated when IV access fails but child cannot tolerate PO (persistent vomiting despite ondansetron)

— Rate: 25 mL/kg/h of ORS via NG × 4 h, then reassess

— Equally effective as IV for mild–moderate dehydration; fewer complications; preferred in many AAP/ESPGHAN guidelines over IV when ORT fails

— Reserve for refractory shock requiring vasopressors, prolonged ICU course, or inability to maintain peripheral access

— Femoral approach often easiest in toddlers; ultrasound guidance

— For accurate urine output measurement in severe dehydration / ICU; target ≥1 mL/kg/h in infants, ≥0.5 mL/kg/h in older children

— Both diagnostic and therapeutic for intussusception (the AGE mimic). Surgical consult on standby for perforation risk.

— Bilious emesis (malrotation/volvulus)

— Peritoneal signs (perforation, appendicitis)

— Palpable abdominal mass (intussusception, pyloric olive)

— Refractory shock despite adequate volume → consider surgical abdomen

IV access:

Nasogastric (NG) rehydration — underused alternative:

Central venous access:

Foley catheter:

Air or saline contrast enema:

Surgical consult triggers in a "gastroenteritis" case:

Dialysis (HUS-related): Initiate for AKI with refractory hyperkalemia, acidosis, fluid overload, uremia, or oligoanuria >24 h. Continuous renal replacement therapy preferred in hemodynamically unstable children.

CCS pearl: If the CCS clock advances and you still cannot get IV access in a shocked 14-month-old, order IO placement explicitly—do not keep retrying peripheral IVs. The grader rewards decisive escalation.

Board pearl: NG rehydration is the right answer on a Step 3 vignette where IV access has failed twice and the child has moderate dehydration with persistent vomiting—it's safer than central line attempts.

Special Populations — Renal/Hepatic Impairment and Comorbid Children

— Cannot concentrate urine → dehydrate faster; cannot excrete K+ → hyperkalemia risk early

— Use isotonic crystalloid cautiously, smaller boluses (10 mL/kg) with reassessment

— Monitor BMP q4h during active resuscitation; avoid potassium-containing fluids until urine output confirmed and K+ known

— Nephrology consult for dosing of any nephrotoxic medication

— Volume overload risk; use 10 mL/kg boluses with reassessment between

— Echocardiography if hemodynamics unclear

— Cardiology consult; may tolerate lower MAP targets

— AGE can precipitate DKA; check glucose, ketones, VBG on every diabetic child with vomiting

— Continue basal insulin (reduced dose) even when NPO; never stop insulin entirely

— Glucose tabs/juice for hypoglycemia, ondansetron for emesis, low threshold to admit

— Inborn errors of metabolism can present like AGE (vomiting, lethargy, acidosis) — check ammonia, lactate, glucose; avoid prolonged fasting (hypoglycemia in fatty acid oxidation defects)

— Use D10 if glucose <60 in metabolic-risk children

— Lower threshold for stool studies, blood cultures, admission

— Higher risk of bacterial/parasitic etiologies (Cryptosporidium, CMV, atypical mycobacteria)

— Consult ID; broaden antimicrobials empirically if febrile neutropenic

— Massive losses; baseline electrolyte derangements; need home care team input on fluid composition

Children with chronic kidney disease:

Children with congenital heart disease / single ventricle / heart failure:

Children with diabetes mellitus (T1DM):

Hepatic disease / metabolic disorders:

Immunocompromised (oncology, transplant, primary immunodeficiency, HIV):

Children with short bowel syndrome / ostomies:

Step 3 management: A 5-year-old with T1DM, vomiting × 12 h, BG 320, HCO3 12, pH 7.25 — this is DKA from AGE, not simple dehydration. Order DKA protocol: NS 10 mL/kg bolus (not 20), then insulin drip 0.05–0.1 U/kg/h after fluid started, monitor for cerebral edema with slow correction.

Board pearl: Cerebral edema risk in DKA is increased by rapid fluid boluses, bicarbonate use, and high effective osmolar swings—favor slower, controlled rehydration.

Special Populations — Neonates, Infants, and Other Subgroups

— Sepsis until proven otherwise: full septic workup (CBC, blood culture, UA + urine culture, LP, CXR if respiratory), empiric ampicillin + gentamicin (or cefotaxime), admit

— Consider surgical causes: malrotation, NEC, Hirschsprung enterocolitis, pyloric stenosis (3–6 weeks)

— Inborn errors of metabolism: ammonia, lactate, plasma amino acids, urine organic acids, acylcarnitines

— Hypothyroidism, CAH (vomiting + hyponatremia + hyperkalemia + hypotension in 2-week-old = salt-wasting CAH, give hydrocortisone + NS)

— Lower threshold for hospitalization for any moderate dehydration

— Bacterial enteritis less common but more severe; consider UTI, sepsis as occult causes

— Continue breastfeeding throughout illness—do not switch to ORS exclusively

— Supplement with small ORS aliquots between feeds for ongoing losses

— Formula-fed: continue full-strength formula; no dilution, no lactose-free switch routinely (post-viral lactase deficiency only if >7 days diarrhea or poor weight gain)

— BRAT diet is outdated—resume regular age-appropriate diet within 4–6 h of rehydration; nutritional rehabilitation improves outcomes

— Avoid juice, soda, sports drinks

— Consider pregnancy testing in postmenarchal females with vomiting

— Consider eating disorders, substance use, IBD as alternatives

— Norovirus outbreaks on cruises, dorms, athletic teams

— Caregiver history is critical; objective markers (weight loss, urine output, capillary refill) more reliable than subjective complaints

Neonates (<1 month) with vomiting/diarrhea:

Young infants (1–3 months):

Breastfed infants:

Toddlers and preschoolers:

Adolescents:

Children with developmental disabilities / nonverbal:

CCS pearl: A 3-week-old with vomiting and lethargy gets a full septic workup including LP even if the parents insist it's "just a stomach bug." The CCS grader will deduct for skipping this in any febrile or ill-appearing neonate.

Board pearl: Continue breastfeeding is almost always the right answer on Step 3 when AGE is the diagnosis in a nursing infant.

Complications and Adverse Outcomes

— Hypovolemic shock → multi-organ failure if untreated

— Acute kidney injury (pre-renal azotemia, ATN if severe)

— Electrolyte derangements: hyponatremia, hypernatremia, hypokalemia, hypoglycemia

— Metabolic acidosis (non-anion gap from stool HCO3 loss, anion gap if shock/ketosis)

— Seizures from hyponatremia, hypernatremia, hypoglycemia, or fever

— Cerebral edema from over-rapid sodium correction (especially hypernatremia)

— STEC → HUS: triad of microangiopathic hemolytic anemia + thrombocytopenia + AKI; days 5–10 of illness; supportive care, dialysis, avoid antibiotics/antimotility/platelets

— Shigella: seizures (neurotoxin), reactive arthritis, rectal prolapse

— Salmonella: bacteremia, osteomyelitis (especially in sickle cell), endovascular infection

— Campylobacter: Guillain-Barré syndrome (weeks later), reactive arthritis

— Yersinia: pseudoappendicitis, post-infectious arthritis (HLA-B27)

— C. difficile: toxic megacolon, perforation, recurrence

— Norovirus / rotavirus: rarely seizures, encephalopathy, intussusception association (older rotavirus vaccine RotaShield)

— Cerebral edema from rapid sodium correction in hypernatremic dehydration (target ≤10–12 mEq/L/24 h drop)

— Central pontine myelinolysis from rapid correction of chronic hyponatremia

— Hyperchloremic metabolic acidosis from large-volume NS resuscitation (LR or balanced crystalloid alternative)

— Hypoglycemia if maintenance fluids lack dextrose

— IV infiltration, IO complications (osteomyelitis, compartment syndrome rare)

— Post-infectious lactase deficiency (transient, weeks)

— Post-infectious IBS

— Reactive arthritis (Campylobacter, Shigella, Salmonella, Yersinia)

— Failure to thrive if recurrent or prolonged

Acute complications of dehydration:

Complications of specific pathogens:

Iatrogenic complications:

Long-term:

CCS pearl: Daily CBC + BMP + Cr in any child with bloody diarrhea for at least 7–10 days from symptom onset to capture HUS evolution, even after discharge if clinically appropriate.

Board pearl: Sudden neurologic deterioration during fluid resuscitation = cerebral edema—stop fluids, elevate head, hypertonic saline 3% 3–5 mL/kg, mannitol, ICU.

When to Escalate — ICU, Consult, and Inpatient Triage

— Failure of ORT despite ondansetron

— Moderate–severe dehydration requiring IV rehydration

— Significant electrolyte abnormality (Na <130 or >150, K <3 or >5.5, HCO3 <15)

— Inability of caregiver to provide reliable home care/follow-up

— Age <6 months with moderate dehydration

— Bloody diarrhea pending workup, comorbid chronic illness

— Persistent vomiting >24 h, intractable diarrhea

— Persistent shock after 60 mL/kg crystalloid

— Need for vasopressors (epinephrine first-line in pediatric septic/distributive shock)

— Severe electrolyte derangement (Na <125 or >160, K >6.5, profound acidosis pH <7.1)

— Altered mental status, seizures

— HUS with AKI requiring dialysis

— Need for mechanical ventilation or continuous renal replacement therapy

— Suspected cerebral edema

— Pediatric ID: atypical pathogens, immunocompromised, prolonged fever, dysentery

— Nephrology: HUS, AKI, dysnatremia requiring careful correction

— Surgery: suspected bilious emesis (volvulus), intussusception not reducible by enema, peritonitis, toxic megacolon

— GI: persistent diarrhea >14 d, suspected IBD, FTT

— Endocrine: DKA, suspected CAH, metabolic crisis

— Genetics/Metabolism: suspected inborn error in neonate

— Public health: reportable diseases (Salmonella, Shigella, STEC, cholera, Giardia, Cryptosporidium in many states; outbreak suspicion)

— Tolerating PO with stable weight

— Urine output ≥1 mL/kg/h (infants) or visible voiding

— Normalizing electrolytes, off IV fluids ≥4–6 h

— Caregiver demonstrates ORS administration and return precautions

— Reliable follow-up arranged within 24–48 h

Admit to general pediatric ward when:

Admit to PICU when:

Consults to call:

Discharge criteria (general ward → home):

CCS pearl: Move the simulation clock to 4–6 h after each major intervention to reassess vitals, urine output, mental status, and PO tolerance; explicit order to "reassess" or "examine patient" is required for the grader to credit your monitoring.

Step 3 management: A child still in compensated shock after 60 mL/kg requires PICU transfer, central access, vasopressors, broad-spectrum antibiotics, and search for alternative diagnosis (septic shock from invasive bacterial enteritis, surgical abdomen).

Key Differentials — Other GI/Infectious Causes

— Periumbilical → RLQ pain, low-grade fever, anorexia, vomiting AFTER pain (not before)

— Diarrhea can occur if retrocecal/pelvic appendix → easy to misdiagnose as AGE

— US or CT; surgical emergency

— 6 mo–3 yr; episodic inconsolable crying with leg-drawing, currant-jelly stool (late), sausage-shaped RUQ mass

— US shows target sign; air enema is diagnostic and therapeutic

— Neonate/infant with bilious emesis ± abdominal distension

— Upper GI series urgently → Ladd procedure if confirmed

— Surgical emergency, ischemic bowel within hours

— 3–6 week-old (especially first-born males), non-bilious projectile emesis after feeds, hungry afterward

— Hypochloremic, hypokalemic metabolic alkalosis

— US shows pyloric thickness >3 mm, length >14 mm; pyloromyotomy

— Premature neonate (or term with risk factors), feeding intolerance, bloody stools, pneumatosis intestinalis on XR

— NPO, NG decompression, broad-spectrum antibiotics, surgery if perforation

— History of delayed meconium passage, chronic constipation, then explosive bloody diarrhea + fever

— Rectal biopsy diagnostic; high mortality

— Chronic bloody diarrhea, weight loss, growth failure, extraintestinal manifestations

— Endoscopy with biopsy

— UTI/pyelonephritis (vomiting in febrile infant)

— Pneumonia (especially RLL → referred abdominal pain)

— Otitis media with vomiting

— Streptococcal pharyngitis (vomiting in school-age)

Same-category mimics that present as "vomiting/diarrhea/dehydration":

Appendicitis:

Intussusception:

Malrotation with midgut volvulus:

Pyloric stenosis:

Necrotizing enterocolitis (NEC):

Hirschsprung enterocolitis:

Inflammatory bowel disease:

Other infectious mimics:

Key distinction: Vomiting before pain = medical (AGE, gastritis); pain before vomiting = surgical (appendicitis, obstruction). This single rule resolves a large proportion of CCS distractors.

Board pearl: Any neonate with bilious emesis gets an emergent upper GI series, not a "wait and see" with ORS.

Key Differentials — Non-GI / Metabolic / Systemic

— 2-week-old infant in shock with hyponatremia + hyperkalemia + hypoglycemia + ambiguous genitalia (or virilized female) = salt-wasting 21-hydroxylase deficiency

— Treat: NS bolus, dextrose, hydrocortisone 25 mg IV (stress dose), fludrocortisone once stable

— Recurrent vomiting/lethargy with anion gap acidosis, hypoglycemia, hyperammonemia

— Urea cycle defects, organic acidemias, fatty acid oxidation defects, MCAD

— Send ammonia, lactate, plasma AAs, urine organic acids, acylcarnitine profile

— Start D10, stop protein intake, dialysis if hyperammonemia severe

— Especially neonates and infants; vomiting and "decreased PO" may be the only signs

— Full septic workup including LP, empiric antibiotics

— Vomiting (often morning, projectile), headache, papilledema, focal neuro signs

— Tumor, hemorrhage, hydrocephalus, abuse

— Neuroimaging

— Iron (vomiting + hematemesis + shock + acidosis), salicylates, acetaminophen, ethanol, hydrocarbons

— Always ask about access to meds, supplements, household products

— Consider non-accidental in unexplained presentations

DKA: new-onset T1DM presents with polyuria → dehydration → vomiting → acidosis. Check glucose and urine ketones in every dehydrated child, especially with Kussmaul breathing, fruity breath, weight loss, polyuria/polydipsia history.

Adrenal insufficiency / CAH:

Inborn errors of metabolism:

Sepsis / meningitis:

Increased intracranial pressure:

Toxic ingestion:

Hemolytic uremic syndrome (post-STEC): as covered—triad of MAHA + thrombocytopenia + AKI

Cyclic vomiting syndrome / abdominal migraine: stereotyped recurrent episodes, well between attacks

Acute hepatitis: vomiting + jaundice + transaminitis

Munchausen by proxy: unexplained, recurrent, inconsistent symptoms; multiple providers; reported but unwitnessed events—mandatory report if suspected

Step 3 management: A 10-day-old in shock with Na 122, K 6.8, glucose 38 — order NS bolus 20 mL/kg, D10 bolus 2 mL/kg, IV hydrocortisone 25 mg, draw 17-OHP and cortisol before steroids if feasible, endocrine consult. Do not anchor on "gastroenteritis."

Key distinction: Hyponatremia + hyperkalemia in an infant = CAH until proven otherwise, not AGE.

Secondary Prevention, Discharge, and Long-Term Plan

— ORS at home (specify brand/quantity; often unavailable—educate on Pedialyte purchase)

— Continue regular age-appropriate diet, including breastmilk/formula

— No anti-diarrheals, no antibiotics unless specific indication confirmed

— Ondansetron home dose not routinely prescribed beyond ED single dose (concerns: masking serious illness, QT, cost-benefit)

— Probiotics optional, not required

— How to administer ORS: 5 mL every 1–2 min, escalate as tolerated

— Replace 10 mL/kg per diarrheal stool and 2 mL/kg per emesis

— Hand hygiene (soap and water; alcohol gel does NOT kill norovirus, C. diff spores)

— Stay home from daycare/school until diarrhea-free for 24 h (Shigella, STEC, Salmonella have specific public health clearance rules—often 2 negative stool cultures)

— Diaper-changing precautions, food safety

— No urine output ≥8 h (infants), ≥12 h (older children)

— Persistent vomiting >24 h, inability to keep down fluids

— Bloody stools or hematemesis

— Lethargy, altered mental status, seizure

— Bilious emesis, severe abdominal pain, distension

— Fever >3–5 days, signs of new infection

— Rotavirus vaccine (RV5 or RV1) — completed by 8 months; check status and catch up if eligible

— Hand hygiene, safe food handling, water safety

— Travel counseling for families heading abroad (bottled water, food precautions)

— Daycare cohorting during outbreaks

— Shigella, Salmonella, STEC, cholera, Giardia, Cryptosporidium, Yersinia, hepatitis A, typhoid—reportable in most US jurisdictions

— Outbreak (≥2 linked cases) reporting

Discharge prescriptions and orders:

Caregiver education (document on chart for CCS):

Return precautions—come back if:

Vaccination & prevention:

Public health reporting:

Step 3 management: At discharge of a 2-year-old after AGE admission, the right answer set includes return precautions, ORS instructions, resume regular diet, confirm rotavirus vaccine status, primary care follow-up in 24–48 hours, school/daycare clearance criteria, and public health reporting if pathogen mandates.

Board pearl: Alcohol-based sanitizers do not inactivate norovirus or C. difficile spores—must use soap and water.

Follow-Up, Monitoring, and Rehab/Counseling

— 24–48 h: PCP phone call or visit; assess hydration, weight, intake, output, diarrhea/vomiting frequency

— 1 week: in-person visit if any persistent symptoms, abnormal labs, or growth concern; recheck weight against pre-illness baseline

— 2 weeks: follow-up if diarrhea persists >7 days—consider post-infectious lactase deficiency, Giardia, or alternative dx; stool studies and dietary trial

— 4 weeks: if symptoms ongoing, refer to pediatric GI for evaluation (IBD, celiac, malabsorption)

— CBC + BMP + Cr + UA twice weekly × 2 weeks from symptom onset to surveil for HUS

— Educate family on signs: decreased urine output, pallor, petechiae, lethargy

— Nephrology follow-up if any HUS features

— Resume regular diet within 4–6 h of rehydration

— Avoid prolonged BRAT diet (inadequate calories/protein)

— If lactose intolerance suspected post-viral, switch to lactose-free formula × 2–4 weeks

— Monitor weight gain trajectory; refer to dietitian if FTT

— In breastfed infants—continue without interruption

— Plot weight, height, head circumference at follow-up visits

— Catch-up vaccinations if missed during illness (especially rotavirus window <8 months)

— Screen for developmental delays if recurrent hospitalizations

— Anticipatory guidance on next illness: ORS preparation, when to seek care

— Address parental anxiety; provide written discharge instructions in preferred language

— Hand hygiene, food safety, daycare practices

— Smoking cessation counseling (secondhand smoke worsens pediatric illness)

— AAP/CDC pathway: ORT-first approach reduces admissions, costs, length of stay

— Avoid routine stool studies, IV fluids, antiemetics beyond evidence-based use

— Document ORT trial before IV escalation for quality metrics

Post-discharge timeline:

Specific follow-up for bloody diarrhea / STEC exposure:

Nutritional rehabilitation:

Developmental and growth monitoring:

Caregiver counseling:

Quality measures and value-based care:

CCS pearl: Schedule the 24–48 h follow-up explicitly in the orders ("follow-up with PCP in 24 hours") and document return precautions—the grader credits transition-of-care quality.

Board pearl: Diarrhea lasting >14 days = chronic; revisit dx, send Giardia/Cryptosporidium antigens, consider celiac, IBD, immunodeficiency.

Ethical, Legal, and Patient Safety Considerations

— Parental consent required for non-emergent care; emergency exception allows life-saving treatment without consent (severe dehydration with shock)

— Adolescents may consent independently for STI testing, contraception, mental health, substance use in most states (mature minor doctrine varies)

— Document discussions and refusals

— If parents refuse IV fluids or admission for a child in clear medical danger → involve child protective services (CPS) and hospital ethics

— Court order may be obtained for life-threatening situations

— Document capacity assessment, alternatives offered, and risks explained

— Suspected child abuse or neglect (including medical neglect from caregiver inattention to dehydration in a chronically ill child) → mandatory CPS report; no need to confirm before reporting

— Munchausen by proxy: unexplained recurrent illness, lab inconsistencies, symptoms only in caregiver presence → report

— Reportable infectious diseases (Salmonella, Shigella, STEC, cholera, etc.) to local health department within state-specified time frames

— Weight-based dosing errors are a leading source of pediatric medication errors—always verify mg/kg dose, double-check with another clinician for high-risk drugs

— Look-alike, sound-alike drugs (e.g., morphine vs hydromorphone) cause harm—use barcoded medication administration

— IV fluid errors: wrong tonicity (hypotonic maintenance fluids cause hospital-acquired hyponatremia; AAP 2018: use isotonic maintenance fluids in most hospitalized children)

— Hand-off communication at shift change—use SBAR or I-PASS; missed HUS surveillance is a classic transition-of-care error

— Discharge teach-back: confirm caregiver can demonstrate ORS preparation and recognize warning signs

— Language-concordant discharge instructions; certified interpreters (not family) for consent

— Address ORS access barriers (cost, transport); WIC/SNAP referral

— Cultural humility: dietary practices, traditional remedies

Informed consent for minors:

Refusal of care / against medical advice:

Mandatory reporting:

Patient safety issues specific to pediatric AGE:

Health systems / equity:

Step 3 management: Hospitalized child receiving D5¼NS develops Na 128 and seizes—this is iatrogenic hyponatremia from hypotonic maintenance fluid, a reportable patient safety event. Switch to isotonic fluid, treat seizure with 3% saline 3–5 mL/kg, debrief and report.

Board pearl: Always use isotonic (NS or LR) maintenance fluids in hospitalized children >28 days unless a specific indication mandates otherwise—per AAP 2018 guidelines.

High-Yield Associations and Rapid-Fire Clinical Facts

— "4-2-1" maintenance fluid rule

— "Bilious = surgical" in neonates/infants

— "Vomit before pain = medical; pain before vomit = surgical"

— "No antibiotics in STEC" (HUS risk)

— "Continue breastfeeding" almost always correct

— 20 mL/kg NS bolus, up to 60 mL/kg before escalating

— 10 mL/kg per diarrheal stool, 2 mL/kg per emesis replacement

— ORS: 50 mL/kg over 4 h (mild), 100 mL/kg (moderate)

— Sodium correction ≤10–12 mEq/L per 24 h

— Urine output goal: 1 mL/kg/h infants, 0.5 mL/kg/h older

— Ondansetron: 2 mg (8–15 kg), 4 mg (15–30 kg), 8 mg (>30 kg)

Norovirus: #1 cause of AGE all ages in US; cruise ships, schools, daycares; alcohol gel doesn't kill it; no vaccine; supportive care.

Rotavirus: unvaccinated infants 6–24 months; vaccine completed by 8 months; previously #1 cause of severe pediatric dehydration globally.

STEC O157:H7: undercooked ground beef, petting zoos, unpasteurized milk; bloody diarrhea → HUS day 5–10; no antibiotics, no antimotility.

Shigella: seizures (neurotoxin) can precede diarrhea; small inoculum; daycare outbreaks; treat severe cases with azithromycin.

Salmonella (non-typhoidal): poultry, eggs, reptiles; sickle cell → osteomyelitis; treat only specific high-risk groups.

Campylobacter: undercooked poultry, raw milk; Guillain-Barré weeks later; reactive arthritis.

Yersinia enterocolitica: pseudoappendicitis; pork; transfusion-associated sepsis.

Vibrio cholerae: rice-water stools; severe dehydration; doxycycline/azithromycin; ORS lifesaving.

C. difficile: post-antibiotic; vancomycin or fidaxomicin; do not test infants <12 months (colonization).

Giardia: mountain streams, daycares, foul greasy stools; tinidazole or nitazoxanide.

Cryptosporidium: waterborne (pool outbreaks); severe/chronic in HIV; nitazoxanide.

Entamoeba histolytica: travel, flask-shaped ulcers, liver abscess; metronidazole + luminal agent (paromomycin).

Mnemonics:

Numbers to memorize:

Board pearl: Hypochloremic, hypokalemic metabolic alkalosis in a 3–6 week-old male with projectile non-bilious emesis = pyloric stenosis, not AGE—correct electrolytes BEFORE surgery (NEVER operate on alkalotic infant; postoperative apnea risk).

Board Question Stem Patterns

"A 2-year-old presents with 2 days of non-bloody diarrhea and vomiting. He has dry mucous membranes, cap refill 2 s, HR 130, BP 90/55, alert. What is the most appropriate next step?"

— Answer: Oral rehydration therapy with ORS, 50–100 mL/kg over 4 h, not IV fluids.

"A 4-year-old develops bloody diarrhea 3 days after a backyard barbecue. Stool studies are pending. What is the most appropriate management?"

— Answer: Supportive care, IV fluids, monitor CBC/Cr/UA; do NOT start antibiotics or antidiarrheals.

"A 5-day-old has 6 hours of bilious vomiting and abdominal distension."

— Answer: Urgent upper GI series; surgical consult (malrotation/volvulus), not ORS.

"A 4-month-old formula-fed with improperly mixed formula has Na 162, doughy skin, irritability."

— Answer: Slow correction over 48 h, isotonic NS initially, target Na decrease ≤10–12 mEq/L per 24 h (rapid correction → cerebral edema, seizures).

"A 14-day-old male presents in shock with Na 120, K 7.0, glucose 35, ambiguous genitalia."

— Answer: NS bolus + D10 + IV hydrocortisone; check 17-OHP.

"A 7-year-old with 2 weeks of polyuria and 1 day vomiting has glucose 380, HCO3 10, ketones positive."

— Answer: DKA protocol (cautious NS, insulin drip after fluid, K replacement, monitor for cerebral edema), not AGE management.

"4-week-old male, non-bilious projectile emesis, hungry afterward, Na 132, Cl 88, HCO3 32, K 3.0."

— Answer: Correct hypochloremic hypokalemic metabolic alkalosis, then pyloromyotomy.

— Answer: Single-dose ondansetron, retry ORT; NG rehydration if ondansetron fails; IV only if NG unavailable/contraindicated.

"Hospitalized child on D5¼NS for 24 h develops Na 126 and a seizure."

— Answer: 3% hypertonic saline 3–5 mL/kg, switch to isotonic maintenance fluid.

Stem 1 — Classic ORT vignette:

Stem 2 — STEC/HUS trap:

Stem 3 — Bilious emesis in neonate:

Stem 4 — Hypernatremic dehydration:

Stem 5 — Salt-wasting CAH mimic:

Stem 6 — DKA mimic:

Stem 7 — Pyloric stenosis:

Stem 8 — Failure of ORT, persistent vomiting:

Stem 9 — Iatrogenic hyponatremia:

CCS pearl: Question stems often hide the right answer behind a "tempting" intervention—resist ordering antibiotics for bloody diarrhea, antiemetics beyond ondansetron, or IV fluids when ORT is appropriate.

One-Line Recap

— ORT first for mild–moderate dehydration: 50–100 mL/kg ORS over 4 h, small frequent aliquots, single-dose ondansetron to break the vomiting cycle and avoid IV/admission.

— IV 20 mL/kg isotonic crystalloid bolus (up to 60 mL/kg) for severe dehydration/shock; if access fails, NG rehydration or IO, not delay; transition to isotonic maintenance fluids with dextrose and KCl once urinating.

— No antibiotics, no antimotility agents in STEC; surveil CBC/Cr/UA for HUS days 5–10; treat targeted bacterial pathogens (Shigella, Campylobacter, severe Salmonella in high-risk hosts) with azithromycin or ceftriaxone.

— Always exclude the dangerous mimics: bilious emesis (malrotation/volvulus), projectile non-bilious in 3–6 week-old (pyloric stenosis), bloody diarrhea (intussusception, STEC, IBD), shock + hyponatremia + hyperkalemia in a neonate (CAH), vomiting with polyuria (DKA), and febrile infant <3 months (sepsis).

— Discharge bundle: resume regular age-appropriate diet, continue breastfeeding, ORS for ongoing losses, explicit return precautions, 24–48 h PCP follow-up, verify rotavirus vaccination, and report notifiable pathogens to public health.

Pediatric dehydration from gastroenteritis is a severity-driven, oral-rehydration-first diagnosis where decisive clinical assessment (cap refill, mental status, weight loss %) selects ORT vs. IV therapy, while vigilant pattern-matching excludes bilious emesis, bloody diarrhea with HUS risk, DKA, CAH, and surgical mimics.

High-yield bullet recaps:

Board pearl: The most commonly missed Step 3 point in this topic is choosing IV fluids when ORT (with ondansetron) is the evidence-based first line—and missing HUS surveillance in a child with bloody diarrhea.