Appendicitis

Content of This Page

 1- Introduction

2- Causes

3- Pathophysiology

4- Signs & Symptoms

5- Differential Diagnosis

6- Risk Factors

7- Investigations & Lab Results

8- Complications

9- Treatment

Introduction

Appendicitis is an acute inflammation of the vermiform appendix, a narrow, finger-like pouch attached to the cecum in the right lower quadrant of the abdomen. It is one of the most common causes of acute abdominal pain requiring emergency surgery, especially in young adults. The condition occurs when the lumen of the appendix becomes obstructed, leading to increased pressure, inflammation, ischemia, and possible infection. If left untreated, appendicitis can progress to serious complications such as perforation, abscess formation, or peritonitis. Prompt diagnosis and surgical removal of the appendix (appendectomy) are the mainstays of treatment to prevent complications and reduce morbidity.

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Causes

  • Lumen obstruction (most common overall cause)

  • Fecalith (hardened stool)

  • Lymphoid hyperplasia (common in children and young adults)

  • Parasitic infections (e.g., Enterobius vermicularis)

  • Foreign bodies (rare)

  • Tumors (e.g., carcinoid tumor, adenocarcinoma)

  • Strictures or fibrosis of the appendiceal lumen

  • Trauma (rare trigger)

© image from www.researchgate.net

Pathophysiology

Appendicitis begins with obstruction of the appendiceal lumen, commonly due to fecalith, lymphoid hyperplasia, or other causes. This obstruction leads to accumulation of mucus and secretions, causing increased intraluminal pressure. The rising pressure impairs venous outflow, resulting in mucosal ischemia and weakening of the appendiceal wall. Ischemia promotes bacterial overgrowth, leading to inflammation, suppuration, and edema of the appendix. If the process continues, it can progress to necrosis and eventual perforation, spilling infectious contents into the peritoneal cavity and causing peritonitis or localized abscess formation

Sign & Symptoms

  • Abdominal pain

    • Starts as periumbilical pain

    • Shifts to the right lower quadrant (RLQ) (McBurney’s point)

  • Nausea and vomiting

  • Anorexia (loss of appetite)

  • Low-grade fever

  • Constipation or diarrhea (less common)

  • Rebound tenderness in RLQ

  • Guarding and abdominal rigidity (signs of peritonitis)

  • Rovsing’s sign – RLQ pain when pressing on the LLQ

  • Psoas sign – pain on hip extension (retrocecal appendix)

  • Obturator sign – pain with internal rotation of flexed right hip (pelvic appendix)

  • Elevated pulse and sometimes mild tachycardia

© image from Wikimedia Commons

Differential Diagnosis

  • Gastroenteritis

  • Mesenteric adenitis

  • Meckel’s diverticulitis

  • Right-sided ureteric colic

  • Urinary tract infection (UTI)

  • Ectopic pregnancy

  • Ovarian torsion

  • Ruptured ovarian cyst

  • Pelvic inflammatory disease (PID)

  • Crohn’s disease (terminal ileitis)

  • Intestinal obstruction

  • Testicular torsion (referred pain in males)

  • Diverticulitis (right-sided, especially in elderly)

Risk Factors

  • Age: Most common in children and young adults (10–30 years)

  • Male sex: Slightly higher incidence in males

  • Diet: Low fiber, high refined carbohydrate intake

  • Family history: Genetic predisposition

  • Infections: Viral or bacterial infections causing lymphoid hyperplasia

  • Previous abdominal infections or inflammation

  • Obstruction: Presence of fecalith or foreign bodies in appendix

© image from radiopaedia.org

Investigations & Lab Results

  • Complete Blood Count (CBC):

    • Leukocytosis (increased white blood cells)

    • Neutrophilia (raised neutrophil count)

  • C-reactive Protein (CRP):

    • Elevated, indicating inflammation

  • Urinalysis:

    • To exclude urinary tract infection or hematuria

  • Pregnancy Test (β-hCG):

    • To exclude ectopic pregnancy in females of childbearing age

  • Imaging:

    • Abdominal Ultrasound:

      • Enlarged, non-compressible appendix (>6 mm diameter)

      • Free fluid or abscess

      • Useful especially in children and pregnant women

    • CT Scan Abdomen and Pelvis:

      • More sensitive and specific

      • Shows enlarged appendix, periappendiceal fat stranding, abscess, or perforation

    • MRI:

      • Alternative in pregnancy or when radiation is a concern

Complications

  • Perforation leading to peritonitis

  • Appendiceal abscess formation

  • Sepsis and systemic infection

  • Wound infection (post-appendectomy)

  • Intestinal obstruction (due to adhesions)

  • Appendiceal rupture causing generalized peritonitis

  • Fistula formation (rare)

Treatment

  • Surgical Removal (Appendectomy)

    • Laparoscopic appendectomy (preferred)

    • Open appendectomy (if laparoscopic not available or complicated cases)

  • Antibiotic Therapy

    • Preoperative broad-spectrum antibiotics

    • Postoperative antibiotics if perforation or abscess present

  • Conservative Management

    • Selected cases with uncomplicated appendicitis may be managed with antibiotics alone (controversial)

  • Supportive Care

    • IV fluids

    • Pain management

    • NPO (nothing by mouth) until surgery

  • Drainage

    • Percutaneous drainage for appendiceal abscess in stable patients before surgery

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