What is the appropriate evaluation and management for an afebrile 3‑year‑old with a five‑day history of abrupt vomiting (now once daily), oliguria, reduced bowel movements, and right upper quadrant (RUQ) pain?

Evaluation and Management of a 3-Year-Old with Vomiting, Oliguria, and Right Upper Quadrant Pain

This 3-year-old requires immediate assessment for dehydration severity and urgent imaging with right upper quadrant ultrasound to evaluate for hepatobiliary pathology, while simultaneously ruling out appendicitis given the atypical age presentation and concerning constellation of symptoms. 1, 2

Immediate Clinical Assessment

Hydration Status Evaluation

The combination of minimal urine output and 5 days of vomiting indicates likely moderate to severe dehydration requiring urgent intervention:

• Moderate dehydration (6-9% deficit): Look for sunken fontanelle (if still open), dry mucous membranes, decreased skin turgor, and prolonged capillary refill >2 seconds 3
• Severe dehydration (≥10% deficit): Assess for severe lethargy, altered consciousness, cool extremities, poor perfusion, and rapid deep breathing indicating acidosis 3
• Decreased urine output (fewer than 4 wet diapers/pull-ups in 24 hours) is a critical red flag 3

Critical Red Flag Assessment

Determine immediately if any surgical emergencies are present:

• Is the vomiting bilious (green)? This indicates obstruction distal to the ampulla of Vater and constitutes a surgical emergency 4, 3
• Is there blood in vomit or stool? "Currant jelly" stools suggest intussusception 4
• Is there abdominal distension or guarding? These suggest mechanical obstruction or peritonitis 1, 5
• Is the pain localized and increasing in intensity? This pattern suggests appendicitis or other surgical pathology 5

Diagnostic Imaging Strategy

Primary Imaging: Right Upper Quadrant Ultrasound

Ultrasound of the RUQ should be the first imaging study performed given the specific complaint of RUQ pain in this child 2, 6:

• RUQ ultrasound can identify hepatobiliary pathology (cholecystitis, cholelithiasis), hepatic abscess, renal pathology, and other causes of RUQ pain 2, 6
• Ultrasound is fast, cost-effective, lacks ionizing radiation, and can provide definitive diagnosis in most cases 2, 6
• While cholecystitis is uncommon in 3-year-olds, other hepatobiliary and renal pathologies can present with RUQ pain and vomiting 6

Secondary Consideration: Appendicitis Evaluation

Although appendicitis is uncommon in preschool children under age 5, it must be considered given the atypical presentation and prolonged symptoms 1:

• Atypical presentations are more common in children <5 years, who may not exhibit classic RLQ pain migration 1
• If clinical suspicion exists after initial assessment, complete abdominal ultrasound (including appendiceal study) is appropriate 1
• Physical examination should assess for decreased bowel sounds, psoas sign, obturator sign, Rovsing sign, and any localized tenderness 5
• The Pediatric Appendicitis Score can help risk-stratify, though imaging remains crucial in intermediate-risk patients 1

When to Obtain Plain Abdominal Radiograph

Order abdominal X-ray if there are signs of intestinal obstruction (abdominal distension, absent bowel sounds, or bilious vomiting) 4, 5

Immediate Management

Rehydration Protocol

Begin oral rehydration immediately unless surgical pathology is suspected:

• Start with small, frequent volumes: 5 mL of oral rehydration solution (ORS) every minute using a spoon or syringe 1, 3
• For moderate dehydration: Administer 100 mL/kg ORS over 2-4 hours 3
• Replace ongoing losses: Give 10 mL/kg ORS for each vomiting episode 3
• Simultaneous correction of dehydration often lessens vomiting frequency 1, 3

Feeding Strategy

Do not withhold nutrition unless mechanical obstruction is suspected 1, 3:

• Continue age-appropriate solid foods immediately, including starches, cereals, yogurt, fruits, and vegetables 1, 3
• Avoid foods high in simple sugars and fats 1, 3

Antiemetic Consideration

Ondansetron (0.2 mg/kg oral, maximum 4 mg) may be considered only if persistent vomiting prevents oral intake entirely, though antiemetics are generally not indicated for routine gastroenteritis in young children 3

Criteria for Immediate Hospitalization and Surgical Consultation

Admit and escalate care immediately if:

• Severe dehydration (≥10% deficit) with signs of shock requiring IV rehydration 3
• Bilious vomiting (mandatory surgical consultation) 4, 3
• Signs of peritonitis: guarding, rigidity, severe localized pain 5
• Inability to tolerate any oral fluids after appropriate trial of small-volume ORS 3

Common Pitfalls to Avoid

• Do not dismiss appendicitis based solely on age: While uncommon in 3-year-olds, delayed diagnosis leads to higher perforation rates in this age group 1
• Do not assume RUQ pain equals right lower quadrant pathology: Young children often have poor pain localization; RUQ pain can represent atypical appendicitis presentation 1
• Do not delay imaging for "observation": Five days of symptoms with oliguria and persistent pain warrants definitive imaging 2, 5
• Do not use CT as first-line imaging: Ultrasound should always be attempted first in children to avoid radiation exposure 1, 2

Parent Instructions for Immediate Return

Instruct caregivers to return immediately or call if:

• Vomiting becomes projectile or bilious (green color) 3
• No urine output for 8-12 hours 3
• Lethargy, altered mental status, or inability to wake child 3
• Bloody vomit or stool 3
• Worsening or severe abdominal pain 5