Appendicitis

• McBurney's point:

  • Located one third of the distance from the right anterior superior iliac spine (ASIS) to the umbilicus
  • Most common location of the base of the appendix
• Appendicitis is inflammation of the appendix and is the most common indication for emergency surgery in paediatric patients.
• Anatomy:

  • The appendix is an intraperitoneal hollow outpouching of the gut which arises from the caecum
  • It is suspended, by the mesoappendix, from the terminal portion of the ileum
  • Commonly sits retrocaecally
  • Carcinoid tumours commonly occur in the appendix
• The appendix is thought to act as a reservoir for intestinal flora which allows the gut to replenish its microbiome after gastroenteritis, but there are usually no long-term consequences to removing it.
• Although the exact pathophysiology is unknown, the typical cause of inflammation is obstruction of the opening of the appendix:

  • Faecolith - hardened stool
  • Lymphoid hyperplasia
• Aetiology and risk factors:

  • Most common in second decade of life
  • Slightly more common in males
  • Children breastfed for less than 6 months and those exposed to tobacco smoke are at an increased risk of appendicitis
• Symptoms:

  • Nausea and vomiting
  • Low-grade fever
  • Umbilical pain
  • Right iliac fossa pain
  • Diarrhoea
  • Anorexia
  • Ask about: urinary symptoms, recent illness and pain history (has it migrated)
• Migration of pain:

  • Initially visceral non specific pain - Initial inflammation stimulates visceral afferent pain fibres which correspond to the T10 dermatome, producing umbilical pain.
  • Then somatic pain - As the appendix becomes more inflamed, it irritates the parietal peritoneum which activates somatic nerve fibres and produces localised pain which is most often felt in the right iliac fossa.
• Typical clinical findings include:

  • Right iliac fossa tenderness
  • Right lower quadrant peritonism
• Additional tests suggestive of appendicitis include:

  • Rovsing sign: palpation of the left iliac fossa causes right iliac fossa pain
  • Psoas sign: extension of the right thigh, in the left lateral position, causes right iliac fossa pain
  • Obturator sign: internal rotation of the flexed right thigh causes pain
  • Hop test: hopping or jumping causes abdominal pain
• Murphy's triad:

  • nausea and vomiting
  • low-grade fever
  • right iliac fossa pain
• Differential diagnoses of paediatric appendicitis include:

  • Mesenteric adenitis: presents similarly to appendicitis, but usually preceded by a sore throat
  • Meckel’s diverticulitis: presents similarly to appendicitis, but symptoms include rectal bleeding
  • Gastroenteritis: general abdominal pain may be present but it will not typically migrate to the right iliac fossa
  • Urinary tract infection: presents with urinary symptoms such as dysuria, frequency and urgency, and urinalysis will commonly show nitrites and white blood cells
• Beside investigations:

  • Urinalysis - to rule out UTI
  • Blood glucose - vomiting may cause hypoglycaemia
  • Baseline observations - low-grade fever may be present
• Laboratory investigations:

  • FBC - raised white cell count
  • U+Es - anorexia and vomiting may caused deranged renal function
  • CRP - suggestive of inflammation
  • Group and save
• Imaging:

  • Typically a clinical diagnosis but imaging can help determine the extent of appendicitis
  • First line - ultrasound
  • CT/MRI
  • CT has good sensitivity and specificity for acute appendicitis and can assess for alternative differentials. Due to radiation exposure this may not be the preferred choice in children and pregnant patients
• Ultrasound findings:

  • Non-compressible appendix (>6mm in diameter)
  • Wall thickening
  • Appendicolith present within the appendix
  • Free fluid within the RIF
• Scoring tools:

  • Appendicitis Inflammatory Response (AIR) score (most reliable)
  • Paediatric Appendicitis Risk Calculator (pARC) (most reliable)
  • Paediatric Appendicitis Score (PAS)
  • Alvarado score
• Management:

  • Antibiotics and laparoscopic appendicectomy is most common management, there are a few cases where this is not the immediate treatment:
  • For some appendix masses, antibiotic therapy is commenced and appendicectomy is delayed several months to allow inflammation to settle
  • Children with large intraperitoneal abscess are more commonly managed with percutaneous drainage
• If there is a delay in presentation with appendicitis, complications can include:

  • Perforation, leading to generalised peritonitis
  • Abscess formation, usually requiring drainage
  • Late complications - intestinal obstruction caused by adhesions, infertility caused by tubal occlusion following pelvic infection