Appendicitis

Appendicitis is one of the most common abdominal emergencies worldwide. Your aim is to be able to diagnose it, distinguish between simple and complex cases and optimise medical management whilst your seniors decide on the timing of surgery.

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Signs and symptoms

  • Murphy’s triad
    • Low-grade fever
    • RIF pain
    • Nausea and vomiting
  • Dull, periumbilical, or epigastric pain that worsens (poorly localised from visceral peritoneum inflammation), becomes sharp, and migrates to the right lower quadrant over 24-48 hours (parietal peritoneum inflammation)
  • General malaise
  • Anorexia
  • Constipation or diarrhoea
  • Abdominal distension, guarding, rebound tenderness (peritonitis)
  • Presents atypically in the very young, elderly, and in pregnancy

Causes

  • Direct luminal obstruction
    • Faecolith
    • Lymphoid hyperplasia
    • Impacted stool
    • Appendiceal or caecal tumour (rare)
  • Risk x3 higher if positive family history
  • More common in males, Caucasians, 2nd -3rd decade of life
  • Environmental
    • Seasonal presentation during the summer

Pathophysiology

  • Luminal obstruction -> continued mucous production -> distension of the appendix -> bacterial overgrowth -> suppurative inflammation -> impaired lymphatic and venous drainage -> ischaemia -> necrosis -> perforation

Classification

  • Uncomplicated (non-perforating)
  • Complicated (gangrenous or perforating)

Complications

  • Usually due to a delay or misdiagnosis of appendicitis
  • Perforation – causes peritoneal contamination
  • Pelvic abscess
  • Sepsis
  • Appendix mass – caused by omentum or small bowel adhering to the appendix
  • Intra-abdominal adhesions
  • Bowel obstruction
  • Post-operative: Surgical site infection and bleeding

Assessment

  • ABCDE and immediate treatment based on findings
  • Abdominal examination is prudent in diagnosing appendicitis
    • Right iliac fossa tenderness
    • Peritonism, guarding, rigidity suggest complicated appendicitis or perforation
  • Specific signs on examination:
    • Rovsing’s sign – RIF pain on palpation of LIF
    • Psoas sign – RIF pain on extension of the right hip
      • Inflamed retrocaecal appendix adjacent to psoas major muscle
    • Obturator sign – pain on internal rotation of the flexed right thigh
  • Always perform a genital examination in boys, to exclude testicular torsion or epididymitis
  • Individual clinical signs have poor predictive value but when combined, their predictive ability is much stronger.
  • The most widely used clinical risk score is the Alvarado score which helps stratify the risk of appendicitis (low, intermediate, high risk)
    • Good sensitivity but low specificity
    • Rarely has a big role in clinical decision making

Differential diagnosis

  • Urological: testicular torsion, epididymitis
  • Gastrointestinal: diverticulitis, inflammatory bowel disease, Meckel’s diverticulum, gastroenteritis
  • Renal: ureteric stones, urinary tract infection, pyelonephritis
  • Gynaecological: ovarian cyst rupture, pelvic inflammatory disease, ectopic pregnancy
  • Paediatric: mesenteric adenitis, intussusception
  • DKA

Initial investigations

Bedside
  • Urinalysis – helps rule out ureteric stones or UTI but leucocytes can be mildly positive in appendicitis (especially if inflamed appendix lies on the bladder)
  • Pregnancy test – to exclude ectopic or normal pregnancy
  • Capillary blood glucose – vomiting and anorexia can lead to hypoglycaemia, also helps rule out diabetic ketoacidosis which may present similarly
  • Baseline observations – usually low-grade fever in appendicitis
Bloods
  • FBC – may show raised white cell count
  • CRP – if raised, suggests inflammation
  • U&E – can be deranged if nausea, vomiting, or diarrhoea are severe
  • LFTs
  • Clotting – part of pre-operative work up
  • G&S – part of pre-operative work up
  • Amylase
Imaging
  • Not essential to diagnose appendicitis, as it can be a clinical diagnosis
  • If other diagnoses as likely as appendicitis, imaging can be used as diagnostic adjunct
  • USS
    • Useful 1st line imaging in females to rule out gynaecological pathology and in children as it does not involve ionizing radiation
    • Operator dependent, not available out of hours, not reliable in patients with significant amount of abdominal fat
  • CT
    • Useful in diagnosing urological, gastrointestinal pathologies
    • Ionizing radiation

Management

  • Escalate immediately if
    • Patient is haemodynamically unstable
    • 10/10 pain
    • Patient looks very unwell
    • Involuntary guarding and rigidity
  • Non-surgical
    • IVF, analgesia, antiemetics
    • Primary antibiotic treatment of uncomplicated appendicitis
      • Failure rate at 1 year of around 25-30%
    • If appendiceal mass present – antibiotic therapy with a delayed appendicectomy 6-8 weeks later
  • Surgical (with pre-operative antibiotic therapy)
    • Laparoscopic appendicectomy remains gold standard
    • Surgery can be delayed allowing longer active monitoring period in:
      • Stable patients admitted overnight, appendix masses, intraperitoneal abscesses

Written by Dr Sara Jasionowska (FY2)

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