What causes left lower abdominal pain with nocturnal nausea and vomiting in a 9-year-old?

Left Lower Abdominal Pain with Nocturnal Nausea and Vomiting in a 9-Year-Old

In a 9-year-old with left lower abdominal pain and nocturnal nausea and vomiting, the most critical immediate concern is to exclude surgical emergencies—particularly intussusception, which can present with crampy pain progressing to bilious vomiting, and appendicitis (though typically right-sided)—before considering more common benign causes like constipation or gastroenteritis.

Immediate Red Flag Assessment

Determine immediately if the vomiting is bilious (green/yellow), as this indicates obstruction distal to the ampulla of Vater and constitutes a surgical emergency requiring urgent imaging and surgical consultation 1, 2, 3.

Critical Warning Signs to Assess:

• Bilious or bloody vomiting 3, 4
• Abdominal distension or absent bowel sounds 3
• "Currant jelly" stools (bloody, mucoid)—pathognomonic for intussusception 2
• Severe, inconsolable crying or drawing up of legs (suggests intussusception) 2
• Altered mental status or toxic appearance 3, 4
• Severe dehydration 3

Differential Diagnosis by Location and Timing

Left Lower Quadrant Pain Specific Considerations:

At 9 years old with left-sided pain, consider:

• Constipation (most common benign cause—can cause left lower quadrant pain and nausea) 5, 3
• Intussusception (can occur at any age, not just infants; presents with crampy intermittent pain, vomiting that may progress to bilious, and bloody stools) 2
• Gastroenteritis (most common cause of acute vomiting in children, though pain is typically diffuse) 3, 6
• Urinary tract pathology (left-sided kidney stones or infection) 3
• Inflammatory bowel disease (if chronic symptoms)

Nocturnal Timing Significance:

The nocturnal pattern is less specific but may suggest:

• Increased intracranial pressure (though would expect morning vomiting and headache) 3
• Gastroesophageal reflux (worsens when supine) 5
• Functional/cyclic vomiting syndrome (if recurrent pattern) 3

Diagnostic Approach

Initial Physical Examination Must Include:

• Vital signs including blood pressure 4
• Hydration status assessment 3, 4
• Abdominal examination for distension, tenderness, masses, bowel sounds 4
• Rectal examination if obstruction suspected 3
• Hernial orifices and genitalia examination 4

Imaging Strategy:

If bilious vomiting or signs of obstruction present:

• Obtain abdominal X-ray immediately as first-line imaging 2
• If obstruction confirmed, proceed to upper GI series or ultrasound depending on suspected pathology 2
• Immediate surgical consultation 2, 3

If non-bilious vomiting with left lower quadrant pain:

• Abdominal X-ray can identify constipation (fecal loading) or other pathology 2
• Ultrasound if intussusception suspected (high sensitivity) 2
• Urinalysis to exclude urinary tract pathology 3

Laboratory Testing Indications:

Order serum electrolytes, blood gases, renal and liver function tests if:

• Any dehydration present 3
• Red flag signs present 3
• Surgical cause suspected 3

Management Algorithm

If Surgical Emergency Suspected (Bilious Vomiting/Obstruction):

1. NPO (nothing by mouth) immediately 3
2. Place nasogastric tube for gastric decompression 3
3. IV fluid resuscitation 3
4. Urgent surgical consultation 2, 3
5. Obtain abdominal X-ray stat 2

If Benign Cause Likely (Non-Bilious, No Red Flags):

For constipation (most common benign cause):

• Discontinue any constipating medications 5
• Initiate stimulating laxative therapy 5
• Ensure adequate hydration 3

For presumed gastroenteritis:

• Oral rehydration with small, frequent volumes 7, 6
• Consider ondansetron 0.2 mg/kg orally (maximum 4 mg) if persistent vomiting impedes oral intake 3, 6
• Ondansetron reduces vomiting rate, improves oral rehydration tolerance, and reduces need for IV rehydration 6

For gastroesophageal reflux:

• Small, frequent meals 7
• Avoid trigger foods 8
• Consider H2 receptor antagonists or proton pump inhibitors if symptoms persist 5

Critical Pitfalls to Avoid

• Never dismiss bilious vomiting as "just gastroenteritis"—it is a surgical emergency until proven otherwise 1, 2
• Do not assume viral gastroenteritis without carefully excluding surgical causes 9
• Intussusception can occur at any age, not just infancy—maintain high suspicion with crampy pain and vomiting 2
• Regular weight checks are essential—poor weight gain elevates concern for pathologic GERD rather than benign reflux 7
• Early reassessment is crucial in undifferentiated vomiting illness to ensure fulminant conditions are not overlooked 9

When to Consult/Refer

Immediate surgical consultation if:

• Bilious vomiting 2, 3
• Signs of intestinal obstruction on exam or imaging 2, 3
• Bloody stools with crampy pain (intussusception) 2

Gastroenterology referral if:

• Chronic symptoms (>4 weeks) without clear etiology 8
• Poor weight gain despite treatment 7
• Suspected inflammatory bowel disease 9