Abdominal Pain in Children: A Comprehensive MCCQE1 Guide

Introduction

Abdominal pain is one of the most common presenting complaints in pediatric emergency departments and primary care clinics across Canada. For the MCCQE1, candidates must demonstrate the ability to differentiate between benign, self-limiting conditions (e.g., constipation, gastroenteritis) and life-threatening surgical emergencies (e.g., appendicitis, intussusception, volvulus).

This guide is structured around the CanMEDS framework, emphasizing the role of the Medical Expert in diagnosis and management, and the Health Advocate and Resource Manager in practicing Choosing Wisely Canada guidelines to avoid unnecessary radiation and interventions.

MCCQE1 Objectives

For MCCQE1 preparation, focus on the following key objectives:

1. Data Acquisition: Elicit a relevant history distinguishing acute vs. chronic pain and identify red flags.
2. Physical Exam: Perform an age-appropriate examination to detect peritoneal signs or masses.
3. Differential Diagnosis: Construct a differential based on age and clinical presentation.
4. Management: Formulate an initial management plan, including appropriate use of analgesia and consultation with pediatric surgery when indicated.

Differential Diagnosis by Age Group

The etiology of abdominal pain varies significantly by age. A structured approach based on age is essential for the MCCQE1.

Clinical Evaluation

History Taking (Medical Expert)

Utilize the OPQRST mnemonic, tailored for pediatrics.

• Onset: Sudden (volvulus, perforation) vs. Gradual (appendicitis, constipation).
• Location: Periumbilical migrating to RLQ (Appendicitis).
• Associated Symptoms: Vomiting (bilious vs. non-bilious), diarrhea, fever, urinary symptoms, rash (HSP).

Physical Examination

1. Inspection: Distension, surgical scars, visible peristalsis.
2. Auscultation: Bowel sounds (high-pitched in obstruction, absent in ileus).
3. Percussion: Tympany (distension), tenderness.
4. Palpation:
   • Start away from the site of pain.
   • McBurney’s Point: Tenderness suggests appendicitis.
   • Rovsing’s Sign: Palpation of LLQ causes pain in RLQ.
   • Psoas Sign: Pain on extension of right hip (retrocecal appendix).
   • Obturator Sign: Pain on internal rotation of right hip (pelvic appendix).

Diagnostic Investigations

Adhere to Choosing Wisely Canada recommendations to reduce unnecessary testing.

Laboratory Studies

• CBC with differential: Leukocytosis with left shift (non-specific but supportive).
• Urinalysis: Rule out UTI or DKA.
• Beta-hCG: Mandatory for all females of childbearing age presenting with abdominal pain.
• Lipase: If pancreatitis is suspected.
• Electrolytes/Glucose: Assessment of dehydration and DKA.

Imaging Modalities

Management Strategies

Management depends on the etiology but generally follows these steps:

Specific High-Yield Conditions for MCCQE1

1. Acute Appendicitis

• Peak Incidence: 10–19 years.
• Diagnosis: Clinical + US.
• Alvarado Score: Used to stratify risk.
• Treatment: Appendectomy. Non-operative management with antibiotics is an emerging topic but surgery remains standard of care for uncomplicated appendicitis in many Canadian centres.

2. Intussusception

• Demographics: 3 months to 3 years.
• Classic Triad: Intermittent colicky pain, vomiting, bloody mucous stools (Currant Jelly). Note: Triad present in <15% of cases.
• Sign: Sausage-shaped mass in RUQ.
• Diagnosis/Treatment: Ultrasound (Target sign/Donut sign) – Air Enema.

3. Malrotation with Volvulus

• Demographics: Usually <1 month (neonates).
• Presentation: Bilious vomiting.
• Diagnosis: Upper GI Series (Corkscrew appearance).
• Treatment: Ladd’s Procedure (Emergent).

Canadian Guidelines & Choosing Wisely

Understanding resource stewardship is key for the MCCQE1.

• Choosing Wisely Canada (Pediatrics):
  • “Don’t order abdominal radiographs for the diagnosis of constipation.”
  • “Don’t do a CT scan for appendicitis as the first-line imaging modality in children.”
• Canadian Paediatric Society (CPS): emphasizes the management of functional abdominal pain involves validating the pain, avoiding triggers, and ensuring return to normal activities (school).

Key Points to Remember for MCCQE1

• Bilious vomiting in a neonate is malrotation with volvulus until proven otherwise.
• Beta-hCG is mandatory for all adolescent females with abdominal pain, regardless of reported sexual history.
• Ultrasound is the imaging modality of choice for pediatric abdominal pain (appendicitis, intussusception, torsion).
• Analgesia does not obscure the diagnosis of appendicitis and should be administered.
• Functional Abdominal Pain is a diagnosis of exclusion but should be considered in school-aged children with chronic periumbilical pain and normal growth.

Sample Question

Scenario: A 4-year-old boy is brought to the Emergency Department by his parents. He has been experiencing intermittent episodes of severe abdominal pain for the past 12 hours. During these episodes, he cries and draws his legs up to his chest. Between episodes, he appears lethargic but pain-free. He has vomited three times; the vomit was initially non-bilious but is now becoming green-tinged. He passed one stool that looked like “red jelly.” His vital signs are: HR 130 bpm, BP 95/60 mmHg, RR 24/min, Temp 37.5°C. On examination, there is a palpable sausage-shaped mass in the right upper quadrant.

Question: Which one of the following is the most appropriate next step in management?

• A. Abdominal X-ray to rule out perforation
• B. Immediate surgical exploration
• C. Air contrast enema
• D. IV antibiotics and observation
• E. Computed Tomography (CT) of the abdomen

Explanation

The correct answer is:

• C. Air contrast enema

Detailed Explanation:

The clinical presentation is classic for intussusception, which is the telescoping of one segment of bowel into another.

• Demographics: Common in ages 3 months to 3 years.
• Symptoms: Colicky, intermittent pain (drawing legs up), lethargy between episodes, and “currant jelly” stool (late sign indicating mucosal ischemia).
• Physical Exam: Sausage-shaped mass in the RUQ and emptiness in the RLQ (Dance’s sign).

Why C is correct: In a stable patient without signs of perforation or peritonitis, an air contrast enema (or liquid enema) is both diagnostic and therapeutic. It reduces the intussusception in the majority of cases. Ultrasound is often done first to confirm diagnosis, but the enema is the management step.

• Why A is incorrect: An abdominal X-ray has low sensitivity for intussusception and is mainly used to rule out perforation (free air). It is not the definitive management step.
• Why B is incorrect: Surgery is reserved for patients with signs of peritonitis, perforation, or if the enema fails to reduce the intussusception. This patient is stable enough for an attempted reduction.
• Why D is incorrect: Antibiotics and observation do not address the mechanical obstruction and bowel ischemia caused by intussusception.
• Why E is incorrect: CT is unnecessary radiation. Ultrasound is the diagnostic modality of choice, and enema is the treatment.

References

1. Medical Council of Canada. MCCQE Part I Objectives: Abdominal Pain. Available at: mcc.ca 
2. Canadian Paediatric Society. Position Statements regarding Acute Care. Available at: cps.ca 
3. Choosing Wisely Canada. Pediatrics: Five Things Physicians and Patients Should Question. Available at: choosingwiselycanada.org 
4. Hospital for Sick Children (SickKids). Clinical Practice Guidelines: Appendicitis. Toronto, ON.
5. Toronto Notes 2024. Pediatrics Chapter: Gastroenterology.