Appendicitis in Pediatrics

James Myall, MD
The Operative Review of Surgery. 2024; 2:322-329.

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Table of Contents

Pathophysiology
Presentation
Diagnosis
Treatment

References

Appendicitis in Adults: *See Appendicitis

Pathophysiology

Normal Anatomy

  • Arises From the Posteromedial Aspect of The Cecum and Inferior to Ileocecal Junction
  • The Tip Has a Variable Location But is Retrocecal in > 60% of Patients 1
  • Typically 6-10 cm Length
  • In The First Year of Life, The Appendix is Funnel-Shaped, Perhaps Making It Less Likely to Become Obstructed 2
  • Lymphoid Follicles are Interspersed in the Colonic Epithelium That Lines the Appendix and May Obstruct it
  • Follicles Reach Their Maximal Size During Adolescence, When Appendicitis Incidence Peaks
  • Omentum is Thin and Underdeveloped in Young Children and May Account for The Diffuse Peritonitis That Usually Follows Perforation in This Age Group

Anatomic Location

  • Located in The Right Lower Quadrant in the Majority of Normal Children
  • May Lie in The Upper Abdomen or On the Left Side in Children with Congenital Abnormalities of Intestinal Position 3
    • Malrotation
    • Situs Inversus Totalis
    • After Repair of Diaphragmatic Hernia
    • Gastroschisis/Omphalocele

Appendicitis Pathology

  • Most Commonly Caused by Nonspecific Obstruction of the Appendiceal Lumen 4
  • Fecal Material (Fecalith) is the Most Common Cause of Obstruction
  • Can Also Be Obstructed by Undigested Food or Other Foreign Material
  • Less Commonly Caused by Direct Infection or Obstruction from Lymphoid Hyperplasia 5
  • Common Infectious Agents:
    • Adenovirus 6
    • Measles 7

Appendix

Presentation

Epidemiology

  • Appendicitis is the Most Common Indication for Emergency Abdominal Surgery in Childhood 8
  • Diagnosed in 1-8% of Children Evaluated Urgently for Abdominal Pain 9
  • Incidence in the United States: 10-12
    • Birth to 4-Years Old: 1-6 per 10,000 Children
    • < 14-Years Old: 19-28 per 10,000 Children
  • < 5% are Diagnosed in Children Under 5 Years Old 13

Perforation

  • In General, Perforation Correlates with Symptom Duration 14
  • Perforation Rates Vary with Age:
    • Neonates: 50-85% 15-18
    • Young Children (< 5 Years): 51-100% 19-25
    • School Age (5-12 Years): 11-32% 26,27
    • Adolescents (>12 Years): 10-20% 28-30
  • Significantly Higher Risk of Perforation at Presentation Than Adults (Particularly in Young Children (< 5 Years Old)
    • Possibly Due to Delayed Presentation
    • Underdeveloped Omentum Has More Difficulty Walling Off an Abscess After Perforation

Presentation/Physical Exam

  • Classic Presentation (Usually in Chronologic Order):
    • Anorexia
    • Periumbilical Pain (Early)
    • Vomiting (After Onset of Pain)
    • Migration of Pain to the Right Lower Quadrant
  • Location of Pain:
    • Initial Periumbilical Pain is Caused by Appendix Stretching Leading to Stimulation of T8-10 Visceral Nerve Fibers
    • Migrating Right Lower Quadrant Pain is Caused by Inflammation of the Surrounding Parietal Peritoneum Leading to Stimulation of the Somatic Nerve Fibers
  • Additional Signs/Symptoms:
    • McBurney Sign: Right Lower Quadrant Tenderness at McBurney’s Point (1/3 the Distance from the Anterior-Superior Iliac Spine (ASIS) to the Umbilicus)
    • Pain with Movement – Ambulation or Shifting in Bed
    • Fever (Commonly 24-48 Hours After Symptom Onset)
    • Difficulty Ambulating
    • Lethargy, Irritability (Neonates and Young Infants)
  • Signs of Peritoneal Irritation:
    • Localized Right Lower Quadrant Tenderness by Cough, Hopping, or Bumping the Exam Table
    • Involuntary Muscle Guarding with Palpation
    • Rebound Tenderness
    • Rovsing Sign: Right Lower Quadrant Pain with Left Lower Quadrant Palpation
    • Iliopsoas/Psoas Sign: Right Lower Quadrant Pain on Extension of the Right Thigh
      • Indicates a Retrocecal Position of the Appendix
    • Obturator Sign: Right Lower Quadrant Pain on Internal Rotation of Right Thigh
      • Indicates a Pelvic Position of the Appendix

Diagnosis

Acute Appendicitis is a Clinical Diagnosis and Should Be Considered in All Children Who Present with Abdominal Pain and Abdominal Tenderness on Physical Exam

Diagnosis

  • Labs:
    • WBC/ANC on CBC with diff – Elevated in Up to 96% of Patients 29
    • C-Reactive Protein (CRP)
      • Use of Both WBC and CRP in Pediatrics Has High Sensitivity and Negative Predictive Value (99%) but Lower Positive Predictive Value (50%) 30
    • Urinalysis Routinely Performed to Identify Alternative Conditions (UTI, Nephrolothiasis)
      • Patients with Appendicitis May Have Incidental Pyuria 31
    • Urine b-hCG Pregnancy Test in All Postmenarchal Females
  • Imaging:
    • Can Be Helpful in Children Who Do Not Present with Typical Signs and Symptoms
    • Children with a Typical Presentation are Considered High Risk for Acute Appendicitis and Consultation with a Pediatric Surgeon Should be Obtained Prior to Imaging
      • Imaging May Be Unnecessary
    • Children with Low Risk for Acute Appendicitis Based on Exam and Labs May Be Managed without Imaging and Instead with Serial Abdominal Exams and Strict Return Precautions
    • Children with Atypical or Equivocal Clinical Findings Suggests Moderate Risk and Warrants Imaging with Ultrasound Being the Preferred Study
    • Adolescent Females Warrant Pelvic Ultrasound with Doppler to Rule Out Ectopic Pregnancy and Ovarian Pathology

Complicated Definitions

  • Uncomplicated (Early) Appendicitis: Acute or Suppurative Appendicitis
  • Complicated (Advanced) Appendicitis: Transmural Bacterial Contamination of the Peritoneal Cavity in Gangrenous or Perforated Appendicitis

Scoring Systems

  • Pediatric Appendicitis Score (PAS) 32
    • The Most Commonly Used System in Pediatrics
    • Points:
      • RLQ Tenderness (2)
      • Pain with Cough, Percussion or Hopping (2)
      • Anorexia (1)
      • Nausea/Emesis (1)
      • Migration of Pain (1)
      • Fever > 38°C/100.5°F (1)
      • Leukocytosis; WBC > 10,000 cells/microL (1)
      • Neutrophilia; ANC > 7,500 cells/microL (1)
    • Interpretation:
      • Low Scores (0-3): Evaluate Other Etiologies
      • Intermediate Scores (4-6): Obtain Imaging to Further Evaluate
      • High Scores (7-10): Imaging vs Surgery
  • Alvarado Scoring System 33
    • The Most Commonly Used System in Adults
    • Points:
      • Tenderness in RLQ (2)
      • Migration to RLQ (1)
      • Rebound Tenderness (1)
      • Anorexia (1)
      • Nausea/Vomiting (1)
      • Elevated Temperature (1)
      • Leukocytosis; WBC > 10,000 (2)
      • Shift of Neutrophils (1)

Treatment

Definitive Management

  • Uncomplicated Appendicitis:
    • Laparoscopic (Over Open) Appendectomy Recommended 34
    • Non-Operative Management with Antibiotics May Be Considered for Select Low-Risk Patients – Surgery is Still Generally the Standard of Care
  • Complicated Appendicitis:
    • Phlegmon or Abscess: Antibiotics and Interval Appendectomy at 10-12 Weeks
      • Percutaneous Drainage Any Abscess > 3 cm 35
      • May Require Urgent Appendectomy if Otherwise Ill-Appearing
    • Gangrenous or Free Perforation: Urgent Appendectomy 36

Antibiotics

  • All Patients Should Receive Broad-Spectrum IV Antibiotics to Cover Colonic Flora as the Diagnosis is Established 37
  • Postop Duration:
    • Uncomplicated: None Necessary
    • Gangrenous But Not Perforated: Stop Within 24 Hours
    • Abscess Drained: 4-Days After Source Control
    • Free Perforation: Generally Continued for 4-5 Days Postop
      • May Consider Discharge on Oral Antibiotics if Discharge Criteria Met (Afebrile, Return of Bowel Function, Adequate PO Intake, and Pain Controlled)

Nonoperative Management

  • Requirements:
    • Abdominal Pain < 48 Hours
    • WBC < 18,000
    • CRP Not Elevated
    • No Peritoneal Signs
    • Imaging Showing:
      • Appendix Diameter ≤ 1.0 cm
      • No Appendicolith
      • No Signs of Perforation
  • Management:
    • Start with IV Antibiotics for 1-2 Days
    • Can Discharge Home on Oral Antibiotics for a 7-10 Day Total Course Once Signs/Symptoms Resolve and WBC Has Normalized 38
  • Comparison to Surgical Management:
    • May Avoid Surgery (80-90% Avoid Surgery at the Initial Admission)
    • May Have a Faster Return to Activity (Shorter Duration of Disability)
    • High Recurrence Rates (40-50% at 5-Years)

Differential Diagnosis/Similar Emergency Surgical Pathology

  • Bowel Obstruction
  • Intestinal Malrotation
  • Intussusception
  • Ovarian Torsion
  • Ectopic Pregnancy
  • Testicular Torsion
  • Omental Torsion

References

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