Large Intestine: Appendicitis

Appendicitis

Appendix Physiology

  • Luminal Capacity of 1 cc
  • Secretes IgA
  • Function: Reservoir for Good Bacteria After Infection Cleans Out
    • *Previously Thought to Be a Vestigial Structure
  • “Vermiform Appendix” Simply References the “Worm-Like” Appearance
  • Positioning:
    • Retrocecal (64%) – Behind the Cecum (Most Common)
    • Subcecal (32%) – Inferior to & Extending from the Cecum
    • Pelvic (2%) – Within Pelvis
    • Preileal (1%) – Anterior to Ileum
    • Postileal (0.5%) – Posterior to Ileum
  • Blood Supply: Appendicular Artery within Mesoappendix (Off the Ileocolic Artery

Appendicitis Pathology

  • Lifetime Risk of Developing: > 15%
  • Cause: Luminal Obstruction & Stasis
    • Most Common Cause:
      • Peds: Lymphoid Hyperplasia
      • Adults: Appendicolith (Fecalith at the Appendiceal Orifice)
    • Leads to:
      • Swelling and Mucous Secretion
      • Impaired Blood Flow & Venous Congestion
      • Bacterial Infection
    • Can Progress to Ischemia & Necrosis
  • Most Common Parasite: Ascariasis lumbricoides

Complicated Appendicitis

  • Definition: Acute Inflammation of the Peritoneum Secondary to Infection of the Appendix
  • Types:
    • Periappendicular Phlegmon
    • Periappendicular Abscess
    • Perforated Appendicitis

Perforation

  • 13-20% Present with Perforation
  • Can be a Contained Walled-Off Abscess or Free Perforation
  • More Common if Presenting After 24 Hours of Symptom Onset
  • Most Common Perforation Site: Midpoint on Antimesenteric Border
  • Risk Factors for Perforation:
    • Age < 4 Years
    • Symptom Duration > 48 Hours
    • Immunodeficiency
    • Hispanic, Black or Asian Race
    • Self-Insured or Public Insurance

Presentation

  • Initial Periumbilical Pain that Migrates to the RLQ (75% Demonstrate Migration)
    • Initial Umbilical Pain Caused by Visceral Peritoneal Fibers from Appendix Stretching
    • Migrating RLQ Pain Caused by Parietal Somatic Fibers from Peritoneal Inflammation
  • Pain Worse with Walking, Jumping or Coughing
  • Anorexia (92%)
  • Nausea (78%)
    • Nausea & Anorexia Occur After Pain Once Secondary Visceral Afferent Fibers Stimulate the Medullary Vomiting Center (Occurs Before Pain in Gastroenteritis)
  • Vomiting (67%)
  • Fever

Appendix Positions 1

Diagnosis

Physical Exam Signs Mn

  • McBurney Sign
    • RLQ Tenderness at McBurney’s Point (1/3 Distance from ASIS to Umbilicus)
    • Most Reliable Finding
  • Rovsing Sign
    • RLQ Pain on LLQ Palpation
  • Iliopsoas/Psoas Sign
    • Pain on Extension of Right Thigh
    • Indicates: Retrocecal Appendix
  • Obturator Sign
    • Pain on Internal Rotation of Right Thigh
    • Indicates: Pelvic Appendix
    • Likely to Cause Dysuria & Diarrhea

Scoring Systems

  • Alvarado/MANTRELS Scoring System
    • Used in Adults, Poor Accuracy in Peds
    • Points:
      • Migration to RLQ (1)
      • Anorexia (1)
      • Nausea/Vomiting (1)
      • RLQ Tenderness (2)
      • Rebound (1)
      • Elevated Temperature (1)
      • Leukocytosis (2)
      • Shift of Neutrophils (1)
    • Low Scores (0-3) Are Better to “Rule-Out” Appendicitis than High Scores (7-10) Are to Rule In
      • Low Scores (0-3): Evaluate Other Etiologies
      • Intermediate-High Scores (4-10): Further Appendicitis Evaluation & Imaging
  • Pediatric Appendicitis Score (PAS)
    • Used for Peds
    • Points:
      • RLQ Tenderness (2)
      • Pain with Cough, Percussion or Hopping (2)
      • Anorexia (1)
      • Nausea/Vomiting (1)
      • Migration of Pain (1)
      • Fever (1)
      • Leukocytosis > 10,000 (1)
      • Neutrophils Plus Band Forms > 7,500 (1)
    • Risk/Scores
      • Low Scores (0-3): Evaluate Other Etiologies
        • 0-2% Risk
      • Intermediate Scores (4-6): Imaging
        • 8-48% Risk
      • High Scores (7-10): Imaging vs Surgery
        • 78-96% Risk
  • Refined Low-Risk Appendicitis Score
    • Used to Rule Out Appendicitis in Peds
    • Factors:
      • Absence of Maximal Tenderness in RLQ OR RLQ Tenderness without Pain on Walking, Jumping or Coughing
      • ANC < 6,750
    • 98% Sensitive & 95% Negative Predictive Value in Identifying Peds without Appendicitis

Diagnosis

  • Adults: CT
  • Peds or Pregnant Women: US
    • If Equivocal Consider MRI (Often Preferred) vs CT
  • Radiographic Findings:
    • Appendix Distended ≥ 6-7 mm
    • Wall Thickening ≥ 3 mm & Noncompressible
    • Appendicolith (10%) – Increases Risk for Complicated Appendicitis
    • Periappendiceal Fluid & Fat Stranding

Appendicitis with Fecalith

Perforated Appendicitis

Treatment

Definitive Management

  • Uncomplicated: Appendectomy
  • Complicated (Phlegmon/Abscess): ABX & Interval Appendectomy at 6-8 Weeks
    • Percutaneous Drainage if Abscess > 3-4 cm
    • ABX Course:
      • After Percutaneous Drainage: 4 Days
      • If Unable to Perform Percutaneous Drainage: 7 Days
    • Immediate Appendectomy:
      • Increased Risk of Complications (SBO, Prolonged Ileus, Surgical Site Infection & Reoperation)
      • May Have Earlier Return to Activity (Debated)
    • Risk of Recurrence: 5-38% (Same as General Population)
    • *Some Recommend No Appendectomy Due to Low Recurrence Rate, Although the Most Compelling Reason for Interval Appendectomy is the Risk of Neoplasm After Perforation
  • Free Perforation: Appendectomy

Intraoperative Findings

  • Normal Appendix: Always Resect (As Long as Cecum Not Inflamed)
    • Prevent Risk of Diagnostic Confusion in the Future
  • Friable Base: Partial Cecectomy; Preserve Ileocecal Valve
  • Suspect Chron’s Disease & Cecum Inflamed: No Intervention

Nonoperative Management

  • Some Promote ABX Treatment Alone for Uncomplicated Acute Appendicitis
  • *In General, Surgical Management is Preferred but May Consider if Unfit for Surgery or Refuses Surgery
  • Benefits:
    • Most Respond Clinically
    • Faster Return to Work (Not for Complicated/Perforated Cases)
    • No Increased Perforation Rate
    • 89-91% Are Able to Avoid Surgery at Initial Admission
  • Negatives:
    • High Recurrence
      • 29% Require Appendectomy by 90 Days
        • 25% Without Appendicolith
        • 41% With Appendicolith
      • 14-37% Require Appendectomy within the First Year
      • Additional 16% Require Appendectomy Between 1-5 Years
    • Tx Efficacy at 1-Year:
      • Nonoperative Management: 63.8%
      • Surgical Management: 93%
    • Contraindicated if Fecalith Present – High Rate of Complicated Appendicitis that May be Underestimated on Imaging
  • Immunocompromised & Significant Comorbidity Patients Have Mostly Been Excluded from Prior Studies with Uncertain Efficacy

Incidental Appendectomy

  • Appendectomy During Another Separate Procedure without Evidence of Appendicitis
  • Indications:
    • Peds About to Undergo Chemo
    • Paraplegic
    • Chron’s
    • About to Travel to Remote Places

Laparoscopic Appendectomy 2

Special Populations

Pediatrics

  • Higher Rate of Perforation & Morbidity (Due to Delayed Diagnosis)
  • Underdeveloped Omentum – Harder to Wall Off Abscess

Pregnancy

  • The Most Common Non-Obstetric Indication for Surgery During Pregnancy
  • Only 50-60% Have a Classical Clinical Presentation
  • Location of Pain:
    • RLQ in First Two Trimesters
    • RUQ by Third Trimester
  • Risk:
    • Nonperforated – 1.5-2.0% Fetal Loss, 6% Preterm Labor
    • Complicated – 8-36% Fetal Loss, 11% Preterm Labor
    • Highest Risk for Fetal Mortality: Rupture
  • Considerations by Trimester
    • First – Most Common Cause of Acute Abdominal Pain
    • Second – Most Frequent Trimester
    • Third – Most Likely to Perforate
  • Tx: Appendectomy
    • Laparoscopic Approach Still Preferred
      • *Previously Concerned for Increased Risk of Fetal Loss/Preterm Labor Now Relieved
    • Trocar Placement: *See Large Intestine: Appendectomy
    • If Preforming Open Make Incision at the Site of Pain (More Cephalad)

HIV/AIDS

  • More Frequent
  • Present Later – Increased Risk of Rupture

Similar Pathology

Mesenteric Lymphadenitis (Pseudoappendicitis)

  • Mesenteric Lymph Node Inflammation
  • Presents Similar to Appendicitis
  • Most Common in Peds
  • Causes:
    • Viral Upper Respiratory Infection (URI) – Most Common
    • Gastroenteritis
    • Inflammatory Bowel Disease
    • Lymphoma
  • Tx: None (No Bx Needed)
    • Resolves Over 1-10 Weeks

Periappendicitis

  • Appendiceal Serosal Inflammation without Mucosal Inflammation
  • Caused by Non-Appendiceal Inflammation
  • Presents Similar to Appendicitis
  • Causes:
    • Salpingitis – Most Common
    • Distant Perforation Elsewhere
    • Pelvic Inflammatory Disease (PID)
    • Peritoneal Tuberculosis
    • Inflammatory Bowel Disease (IBD)
  • Valentino’s Syndrome – Peri-Appendicitis Caused by a Perforated Gastric/Duodenal Ulcer

Appendiceal Mucocele (Non-Neoplastic Mucinous Lesion/Retention Cyst)

Appendix Cancer

Mnemonics

Signs of Appendicitis

  • McBurney Sign – “Burns” Right Over the Appendix
  • Rovsing Sign – Think “Roving” Pain Elicited from a Distant Site
  • Psoas Sign (Pso-Po) – Posterior (Retrocecal)
  • Obturator Sign (Ob-Ob) – Obstetrics (Pelvic Location & Internal Rotation to Pelvis)

References

  1. Bakar SM, Shamim M, Alam GM, Sarwar M. Negative correlation between age of subjects and length of the appendix in Bangladeshi males. Arch Med Sci. 2013 Feb 21;9(1):55-67.(License: CC BY-NC-ND-3.0)
  2. Strzałka M, Matyja M, Rembiasz K. Comparison of the results of laparoscopic appendectomies with application of different techniques for closure of the appendicular stump. World J Emerg Surg. 2016 Jan 6;11:4. (License: CC BY-4.0)