Appendicitis Summary

Pathophysiology

  • Acute inflammation of the appendix
  • Often caused by luminal obstruction
  • Leads to distension, bacterial overgrowth, and potential perforation

Clinical Features

  • Migrating abdominal pain to RLQ
  • Fever, malaise, anorexia
  • Nausea and vomiting
  • Tenderness at McBurney's point

Alvarado Score

  • Migration of pain: +1
  • Anorexia: +1
  • Nausea/vomiting: +1
  • RLQ tenderness: +2
  • Rebound tenderness: +1
  • Fever: +1
  • Leukocytosis: +2
  • Left shift: +1

Management

  • Imaging: US, CT, or MRI
  • Non-operative: IV fluids and antibiotics
  • Operative: Appendectomy (laparoscopic preferred)

Complications

  • Appendix mass or abscess
  • Generalized peritonitis
  • Sepsis
  • Postoperative complications

Appendicitis

Medical guidelines for diagnosis and management

Pathophysiology

Appendicitis describes an acute inflammation of the appendix. The aetiology and pathogenesis of acute appendicitis remain largely unknown, but it is thought to be caused by luminal obstruction in about 50% of cases.

Causes of Obstruction

The main causes of luminal obstruction are thought to be faecolith (hard mass of faecal matter), lymphoid hyperplasia during an infection, impacted stool, foreign body, or rarely appendiceal or caecal tumour.

Disease Progression

Luminal obstruction leads to distension of the appendix owing to increased mucus production, bacterial overgrowth, and suppurative inflammation.

Complications

This results in impaired lymphatic and venous drainage from the appendix, with eventual ischaemia and necrosis, and potential perforation.

Clinical Features

Diagnostic Challenge

Suspect a diagnosis of acute appendicitis if there are suggestive clinical features on history and examination. Establishing a diagnosis may be challenging, as it may present atypically and vary in severity.

Typical Symptoms

Abdominal pain - Periumbilical or epigastric pain that worsens, and migrates to the right lower quadrant over 24–48 hours. Often worsened by movement. Note: a history of sudden relief of pain may indicate appendiceal perforation.
Systemic symptoms - Fever (often low grade), general malaise, and anorexia.
Gastrointestinal symptoms - Nausea and vomiting. Constipation (or sometimes diarrhoea).

Typical Signs

General appearance - Facial flushing, dry tongue, halitosis, low-grade fever (less than 38°C), and/or tachycardia.
Abdominal examination - Tenderness in the right lower quadrant. The site of maximal tenderness is typically over 'McBurney’s point', which lies two-thirds of the way along a line drawn from the umbilicus to the anterior superior iliac spine.
Signs of peritonitis - Abdominal distension, guarding (muscular rigidity), and rebound tenderness or percussion tenderness may suggest peritonitis. Absent bowel sounds may indicate ileus or peritonitis associated with perforation.
Special signs for appendicitis:
  • Rovsing's sign — palpation of the left lower quadrant increases the pain felt in the right lower quadrant
  • Psoas sign — passive extension of the right thigh with the person in the left lateral position elicits pain in the right lower quadrant
  • Obturator sign — passive internal rotation of the flexed right thigh elicits pain in the right lower quadrant

Atypical Presentations

Children

Infants and young children may present with non-specific abdominal pain and anorexia, and may appear withdrawn.

Older Patients

There may be minimal pain or fever; may present with acute confusion or shock.

Pregnancy

There may be displacement of the appendix by the gravid uterus. In later stages, may present with right upper quadrant or right flank pain. Nausea and vomiting may be mistaken for pregnancy-related symptoms.

Variant Anatomical Positions

Retrocaecal/Retrocolic

May present with right loin pain and tenderness, and a positive psoas test. Muscular rigidity and tenderness to deep palpation are often absent because of protection from the overlying caecum.

Pre-ileal and Post-ileal

May present with vomiting and diarrhoea (due to irritation of the distal ileum).

Subcaecal and Pelvic

May present with suprapubic pain and urinary frequency; diarrhoea and tenesmus may be present owing to rectal irritation; abdominal tenderness may be lacking, but rectal or vaginal tenderness may be present on the right side.

Types of Abdominal Pain

Visceral Pain

  • Caused by stretching of hollow viscus or capsule of solid viscus or chemical irritation
  • Locality of pain dependent on embryologic origin of viscera
  • Less severe
  • Poorly localised
  • Dull or aching pain
  • May be intermittent or constant

Parietal Pain

  • Caused by irritation of the parietal peritoneum
  • Pain is localised to the region of abdominal wall that the parietal peritoneum lines
  • More severe
  • Easily localised
  • Sharp, stabbing pain
  • Constant pain

Differential Diagnosis

Consider these alternative diagnoses when evaluating a patient with suspected appendicitis.

Gastrointestinal

Gastroenteritis, intestinal obstruction, incarcerated inguinal hernia, intussusception, volvulus, Meckel diverticulum, biliary colic and acute cholecystitis, perforated peptic ulcer, diverticulitis, pancreatitis, inflammatory bowel disease, irritable bowel syndrome, constipation, mesenteric adenitis

Urological

Ureteric colic, pyelonephritis, UTI, urinary retention, testicular torsion

Gynaecological

Ectopic pregnancy, ruptured ovarian cyst, ovarian torsion, Mittelschmerz, pelvic inflammatory disease, endometriosis or adenomyosis, fibroids, dysmenorrhoea

Other

Basal pneumonia, back pain, abdominal wall abscess or haematoma, DKA, shingles

Investigations

Consider the need for additional investigations to exclude an alternative cause, depending on clinical judgement.

Full Blood Count

Neutrophil-predominant leucocytosis is present in 80–90% of people with appendicitis.

C-reactive Protein (CRP)

Raised levels may be present, but normal levels do not exclude a diagnosis of appendicitis.

Urine Dipstick Test

To help exclude a urinary tract infection (UTI).

Pregnancy Test

To exclude ectopic pregnancy and other pregnancy-related conditions.

Alvarado Clinical Scoring System

The Alvarado score predicts the likelihood of appendicitis diagnosis in patients presenting with suspected acute appendicitis.

Sign/Symptom
Score
Right lower quadrant tenderness
+2
Elevated temperature (>37.3°C)
+1
Rebound tenderness
+1
Migration of pain to right lower quadrant
+1
Anorexia
+1
Nausea or vomiting
+1
Leukocytosis >10,000
+2
Leukocyte left shift (>75% neutrophils)
+1

≤4 Points

Unlikely appendicitis

5-6 Points

Possible appendicitis

≥7 Points

Likely appendicitis

Management

Specialist management of suspected acute appendicitis may include various approaches depending on the clinical scenario.

Imaging Investigations

Imaging studies in people with a clinical suspicion of acute appendicitis can reduce the negative appendectomy rate, which has been reported to be as high as 15%.
Ultrasonography, abdominal computed tomography (CT) and magnetic resonance imaging (MRI) are most commonly used.

Non-operative Management

After imaging, a non-operative management strategy with intravenous fluids and antibiotics can be a safe and effective approach in selected patients with uncomplicated acute appendicitis.

Operative Management

Removal of the appendix is the gold standard treatment for appendicitis.
In people with progressive or persistent pain, exploratory laparoscopy is recommended to establish/exclude the diagnosis of acute appendicitis or alternative diagnoses.
Laparoscopic appendicectomy offers significant advantages over open appendicectomy in terms of less pain, lower incidence of surgical site infection, decreased length of hospital stay, earlier return to work, overall costs, and better quality of life scores.

Complications

Appendicitis may be uncomplicated (non-perforating) or complicated (perforating). A delay or misdiagnosis of appendicitis can result in additional severe complications.

From Perforation

Appendix Mass

The inflamed appendix becomes walled off by omentum and surrounding viscera to form an inflammatory mass.

Appendix Abscess

Localized collection of pus resulting from perforation.

Generalized Peritonitis

Inflammation of the peritoneum resulting from perforation and spillage of intestinal contents.

Sepsis

Life-threatening organ dysfunction caused by a dysregulated host response to infection.

Intra-abdominal Adhesions

Bands of scar tissue that form between abdominal tissues and organs.

Postoperative Complications

Small Bowel Obstruction

Blockage in the small intestine that prevents normal digestion.

Superficial Wound Infection

Infection at the surgical incision site.

Intra-abdominal Abscess

Collection of pus inside the abdomen after surgery.

Stump Leakage

Leakage from the appendiceal stump after appendectomy.

Stump Appendicitis

Inflammation of the residual appendiceal stump after incomplete appendectomy.