What is the best course of action for a 15-year-old boy with severe abdominal pain, no nausea, no vomiting, no diarrhea, normal bowel and bladder habits, and present bowel sounds?

Immediate Diagnostic Workup for Severe Abdominal Pain in a 15-Year-Old Boy

This 15-year-old boy with severe abdominal pain, normal bowel sounds, and no peritoneal signs requires immediate CT abdomen/pelvis with IV contrast to rule out mesenteric ischemia, bowel obstruction, and other surgical emergencies, as severe pain without proportionate physical findings is a red flag for life-threatening conditions. 1, 2

Critical Initial Assessment

Immediate hemodynamic evaluation is mandatory:

• Check vital signs for tachycardia, hypotension, fever, and tachypnea—these combinations predict serious complications including bowel ischemia or sepsis 2
• Tachycardia alone is a critical warning sign and should trigger aggressive investigation 2
• Signs of shock mandate immediate surgical exploration without delay 2

The presence of severe pain with minimal physical findings is the classic presentation of acute mesenteric ischemia until proven otherwise 1, 2

Focused History and Physical Examination

Key historical elements to obtain immediately:

• Prior abdominal surgery (85% sensitivity for adhesive small bowel obstruction) 2
• Timing and character of pain onset—sudden onset suggests vascular catastrophe 1
• Any bilious or feculent vomiting (indicates mechanical obstruction requiring immediate nasogastric decompression) 2
• Constipation pattern (triad of pain, constipation, and vomiting suggests sigmoid volvulus) 2

Critical physical examination findings:

• Assess for peritoneal signs (rebound tenderness, guarding, rigidity)—these indicate possible perforation or bowel necrosis 2
• Evaluate for abdominal distension with diminished bowel sounds (classic for bowel obstruction) 2
• Perform digital rectal examination—empty rectum supports complete obstruction 2
• Critical caveat: Absence of peritonitis does NOT exclude bowel ischemia—laboratory tests are essential 2

Mandatory Laboratory Testing

Obtain immediately:

• Complete blood count, electrolytes, renal function 2, 3
• Blood gas and lactate levels—essential for detecting bowel ischemia 2
• C-reactive protein (predicts postoperative complications and serious pathology) 2
• Liver function tests 2

Elevated lactate and metabolic acidosis are late findings in mesenteric ischemia but indicate advanced disease requiring immediate intervention 1

Imaging Strategy

Plain abdominal radiograph has NO role as the primary diagnostic test:

• Limited sensitivity—25% of patients with acute mesenteric ischemia have normal radiographs 1
• Negative films do NOT exclude mesenteric ischemia or early obstruction 2
• Should only be used to screen for bowel perforation or obstruction 1

CT abdomen/pelvis with IV contrast is the definitive diagnostic test:

• Identifies obstruction, transition points, bowel ischemia, and surgical causes 2, 3
• Fast, accurate, and distinguishes mechanical obstruction from functional causes 1
• Prevents unnecessary laparotomy by providing definitive diagnosis 2
• For suspected mesenteric ischemia specifically, CT angiography should be performed immediately 1, 2

Immediate Management While Awaiting Imaging

Initiate aggressive supportive care:

• IV fluid resuscitation with aggressive crystalloid administration 2
• NPO status immediately 2
• Consider nasogastric tube decompression if any vomiting develops 2
• Obtain immediate surgical consultation given severity of pain 2

Age-Specific Considerations

In adolescents, consider additional diagnoses:

• Appendicitis remains common in this age group 4, 3
• Testicular torsion with referred pain (if male) 3
• Ovarian torsion or ectopic pregnancy (if female with reproductive organs) 3
• However, severe pain out of proportion to examination findings takes precedence and mandates ruling out mesenteric ischemia first 1, 2

Common Pitfalls to Avoid

Do not be falsely reassured by:

• Normal bowel sounds—these can be present early in mesenteric ischemia 1
• Absence of peritoneal signs—ischemia can exist without peritonitis 2
• Normal initial laboratory values—lactate elevation is a late finding 1
• Patient's age—mesenteric ischemia, while more common in elderly, can occur in younger patients with embolic sources 1

Do not delay imaging for serial examinations when pain is severe 2

Disposition Algorithm

If CT shows:

• Mesenteric ischemia → immediate surgical exploration 1, 2
• Bowel obstruction → serial abdominal exams every 4-6 hours to detect peritonitis, surgical consultation 2
• Appendicitis or other surgical pathology → appropriate surgical intervention 3
• No acute findings → consider functional causes only after excluding organic disease, but maintain high suspicion and arrange close follow-up 5