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Acute Appendicitis

Section: Emergency Curriculum: Curriculum, page 27

See Appendix Anatomy

Definition

  • Inflammation of the appendix

Epidemiology

  • 5-10% lifetime risk
  • Slight male preponderance

Classification

  • Uncomplicated
  • Complicated - perforation, gangrenous, phlegmon, missed

Aetiology

  • Lymphoid hyperplasia
  • Faecolith
  • FB - worms
  • Neoplasms

Pathophysiology

  • Luminal obstruction (faecolith, lymphoid hyperplasia, tumour or mucocoele)
    • Increased intraluminal pressure → venous and lymphatic occlusion and congestion
    • Stasis of lymphatic flow and build up of intraluminal mucus to further increase pressure
    • Subsequent arterial occlusion → localised ischaemia/necrosis
    • Bacterial overgrowth - E.coli, Bacteroides, pseudomonas, peptostreptococcus
    • Perforation and contained abscess or peritonitis (focal or generalized)
  • Of Pain
    • Visceral
      • Appendiceal engorgement stimulates visceral afferent nerve fibres entering the spinal cord at T8-T10 → visceral peritoneal → central abdominal pain
    • Parietal
      • Intraluminal bacteria invading the wall causes neutrophil influx into wall and fibropurulent serosal irritation → parietal peritoneal (somatic nerve stimulation)→ localised pain
  • Summary
    • Luminal obstruction and mucous production → increased P
    • Venous and lymphatic then arterial occlusion/stasis - ischaemia
    • Bacterial overgrowth and wall invasion
    • Perforation → contained abscess or peritonitis
    • Neutrophilic infiltration of muscularis propria = REQUIRED for dx

Clinical

  • Migratory abdominal pain central to RIF with loss of appetite and N+V
  • Febrile with RLQ tenderness
  • Rovsing’s sign - RLQ pain with LLQ palpation

Investigations

  • Bloods
    • Inflammatory markers, hCG, renal function
  • Urinalysis
  • Imaging
    • USS (75% sensitive and 95% specific)

      • 7mm diameter

      • Non compressible, probe tender structure in RIF, blind ending
      • Hyperechoic appendicolith
  • CT (95% sensitive and 100% specific)
    • Thick walled with enhancement of the wall and periappendiceal fat stranding
  • Differential diagnosis
    • GIT
    • Terminal ileitis
    • Gastroenteritis
    • Right sided diverticulitis
    • IBD
    • Meckels
    • GUT
    • Ectopic pregnancy
    • Ovarian torsion
    • TOA
    • Cyst accident
    • UTI/renal stone
    • MSK
    • Trauma

Management

  • Principles of management
    • Pre-operative - resuscitation (IVF) and early IV abx
    • Post-operative - ERAS, ensure no unexpected findings on histology
  • Non-operative
    • In uncomplicated appendicitis it is an option
    • Contraindications
      • Diffuse peritonitis
      • Septic/unstable
      • Immunocompromised
      • Pregnant
      • IBD
    • Relative contraindications
      • Appendicolith
      • Elderly
    • Avoids surgery/GA with less recovery and no associated extra risk of rupture
    • Negatives are the failure rates and risk of missed neoplasm
      • CODA trial - 30% underwent appendicectomy within 3 months, 50% at 2 years.
      • Also risk of missed neoplasm
      • Appendicolith was a risk factor for non-operative management failure - 40% at 3 months had undergone appendicectomy.
  • Surgery
    • Laparoscopic appendicectomy
      • Benefits
        • Diagnostic and therapeutic
        • Shorter hospital LOS
        • Less pain and wound infection rates
    • Surgical Considerations
      • Delay to surgery
        • Higher risk of complications - perforation, wound infection
      • Normal appendicectomy
        • Rate is 25%
        • Higher for young females
        • If normal
          • Leave alone if there is an alternate pathology
          • Remove if equivocal or normal laparoscopy
            • R/O appendicitis and prevent future episode
      • Appendiceal mass
        • Requires imaging ideally
        • If found prior - IV abx unless pt is unwell or failed abx, then would get a IR drain trial prior to surgery
        • If found at surgery and difficult dissection
          • Can close and continue abx/leave a drain
        • Consider interval appendicectomy
          • If high risk features, >40, immunocompromised, appendicolith
          • Only 5-10% risk of recurrent appendicitis?
          • Increased risk (?10%) of malignancy in >40yo
            • Will require colonoscopy if >40 y/o’
      • Laparoscopic vs open
        • Lap - less wound infection, less post op pain and reduced LOS
        • Open - less intra-abdominal abscesses, shorter operative time
        • Generally lap is preferred in all instances
      • Irrigation
        • Best to suck mucky fluid to dryness
        • Do not do large volume wash - increased risk of collections

Prognosis

  • Risk of incidental neoplasm - 0.5-1%
    • NET or adenocarcinoma
  • Complications
    • Gangrene
    • Perforation
      • Who is more likely to perforate? Young, longer duration and smokers
      • Increased infertility
    • Peritonitis
    • Abscess
    • Portal pyaemia
      • Liver abscesses
  • Post-surgical complications
    • Collection - pelvic or pericaecal
    • Wound infection
    • Higher risk of both if perforated
  • Chronic appendicitis
    • 3/52 duration or longer
    • Similar management to acute

Exam Fodder

  • Uncomplicated
    • Abx and surgery vs abx alone
    • Discussion around risks
    • Failing abx then leads to surgery
  • Complicated
    • Surgery mainstay
    • If longer hx and collection 3cm - IR drain and delayed surgery
    • If failing then surgery
    • If non-operative management
      • Consider interval appendicectomy
        • If high risk features, >40, immunocompromised, appendicolith
        • Only 5-10% risk of recurrent appendicitis?
        • 10% risk of malignancy in >40yo
        • Will require colonoscopy if >40 y/0

Appendicitis in Pregnancy

Clinical

  • Similar but
    • 10-15% can present with preterm labour
    • Less likely to have a classical presentation if in late pregnancy - atypical pain
    • RUQ or mid abdominal - uterus pushed appendix cranially
  • Signs
    • Adler’s sign is shifting tenderness
      • Maximal tenderness in supine position identified
      • Rotate patient to left side - if pain migrates to midline - likely a gynaecological cause
    • Bryan’s sign - pain with uterus shifted to the right

Investigations

  • Pregnancy leukocytosis can be up to 16 normally and 30 in labour
  • Imaging
    • USS - not sensitive and difficult to visualise appendix
    • Can lead to delay in dx and tx
  • MRI
    • Sensitive 94% and specific 97%
    • Gadolinium not given due to fetal safety concerns (no evidence)
  • CT
    • Only 3mGy of radiation and fetal anomalies - at 30+
    • Limited radiation dose but should be last line

Management

  • Same principles apply
  • Risk of preterm labour and fetal loss is higher/similar with intra abdominal infection of appendicitis and GA/surgery
  • Higher risk with more complicated appendicitis and delay to surgery
  • Lap vs open
  • Open or port placement needs to accommodate for a higher appendix positioning in later pregnancy
  • Left tilt important to minimise IVC compression
  • Limit intra-abdominal pressures, avoid uterocervical instrumentation and place all ports under direct vision

Graph View

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