Appendicitis Flashcards
Define appendicitis.
Acute appendicitis is an acute inflammation of the vermiform appendix, most likely due to obstruction of the lumen of the appendix (by faecolith, normal stool, infective agents, or lymphoid hyperplasia).
How common is appendicitis?
- Most common surgical emergency - 50,000 per year done in UK
- Usually early teens and late 40s
- Appendicitis M>F (8.6% vs 6.7%)
- Appendectomy F>M (almost 2:1)
What is the aetiology of appendicitis?
Obstruction of the lumen of the appendix by…
- faecolith (40%)
- normal stool
- lymphoid hyperplasia
- rarely appendiceal or caecal tumour
What are the risk factors for appendicitis?
- FH (x3)
- Peaks in summer months
- <6months of breastfeeding
- Low fibre diet
- Hygiene - use of antibiotics and imbalance of GI microbial flora can lead to a modified response to infection and appendicitis
- Malignancy
- Infection with Bacteroides or E. coli.
Describe the pathophysiology of appendicitis.
- Lumen distal to obstruction fills with mucous and a closed-loop obstruction forms → distension + increase in intra-luminal pressure
- Resident bacteria in appendix rapidly multiply - most commonly Bacteroides fragilis and E. coli.
- Distension of lumen of appendix → reflex anorexia, nausea, vomiting, visceral pain
- As pressure in lumen exceeds venous pressure → small venule and capillary thrombosis but arterioles are open → engorgement and congestion in appendix → (anti-mesenteric border becomes ischaemic → infarction and perforation*)
- Inflammation of the serosa layer occurs → parietal peritoneum → LIF pain
- If perforation occurs, bacteria leaks out around appendix and pus starts to form → abscess. Perforations are usually beyond obstruction rather than at tip of appendix.
How does pattern of pain progress in appendicitis?
- Visceral pain referred to epigastric region
- Peritonitic pain (usually 24-48hrs since onset) is localised in RIF
Atypical appendiceal anatomy, such as retrocaecal or long appendix, may present with back, hip, or left-sided abdominal pain. Older patients are less likely to have classical symptoms
What is a typical presentation of appendicitis?
- Abdominal pain -
- Constant mid-abdominal pain t
- Later shifts after 24-48hrs to RIF
- Worse on movement e.g. classically when driving and there are bumps
- Anorexia - without this the diagnosis is in question
- Low grade fever and malaise
- Nausea and vomiting
- Fetor
What are the signs of appendicitis on physical examination?
- McBurney’s sign - RLQ tenderness, localised rebound tenderness
- Rovsing’s sign - pressing the LLQ may also elicit pain in the RLQ
- Rebound tenderness - more painful on removing hand than on pressing firmly
- Percussion tenderness
- Psoas sign - pain elicited with the patient lying on their left side and slowly extending the right thigh (stretches the iliopsoas)
- Obturator sign - pain elicited by internal rotation of the flexed right thigh
Other:
- Fever (low-grade. 1o), tachycardia
- Reduced bowel sounds - ?peritonitis
- Distension, guarding
- Appendiceal mass or abscess
What clinical scoring system may be used to stratify patients with appendicitis?
Alvorado score - 5/6 is usually acute appendicitis, 7/8 is probable appendicitis, 9/10 very probable appendicitis.
Although this has largely been superseded now but AIRS (appendicitis inflammatory response score)
When will the WCC vs CRP be high in appendicitis?
Leucocytosis within 5-24hrs of symptoms
CRP only raised after >12hrs of symptoms
What investigations would you do for acute appendicitis?
Bedside:
- FBC - neutrophil predominant leucocytosis in ~80%
- CRP - may be raised
- VBG/ABG - check lactate and acidosis
- Glucose
- U&Es - hypokalaemia can cause pseudo obstruction
- LFTs -?gallstones
- ECG
- Group and save - if having surgery
- Urinary pregnancy test - ectopic pregnancy
- Urinalysis - exclude UTI/stones
Imaging:
- US abdomen - useful for also excluding ovarian pathology in females and renal tract pathology
- CT abdo/pelvis* - abnormal appendix (diameter >6 mm) identified or calcified appendicolith seen in association with peri-appendiceal inflammation (MRI if pregnant)
- +/- AXR
- +/- colonoscopy - if change in bowel habit and PR bleeding
NB: in children diagnostic laparoscopy is safer than abdo CT
What features on imaging suggest an inflamed appendix?
USS - (~80% sensitive, ~85% specific) aperistaltic or non-compressible structure with outer diameter >6mm
CT contrast - (>90% sensitive, ~95% specific) wall thickening, >6mm diameter or calcified appendicolith, wall enhancement, inflammatory changes in surrounding tissues
What are features of complicated appendicitis?
- Gangrenous appendix with or without perforation
- Intra-abdominal abscess
- Peri-appendicular phlegmon
- Purulent-free fluid
How do you manage acute appendicitis?
ABCDE
Fluid resuscitation
NBM
Analgesia
Immediate surgical review
+/- Prophylactic antibiotics - do not give these until the surgical team have arrived as it can mask symptoms
Laparoscopic appendicectomy - first line management; should be done within 24hrs and ideally in <8hrs in children to reduce risk of perforation.
When can you use conservative treatment in appendicitis?
E.g. only using ceftriaxone 1g/day + metronidazole 500mg/TDS IV . Used more commonly during the pandemic
Uncomplicated appendicitis ONLY + those who are not fit for surgery or do not wish to have it. But risk of recurrence.
Do not use conservative management in:
- Pregnant
- If appendicolith present
Can be used in children.
How might different anatomical positions of the appendix affect presentation?
Retrocaecal→ right loin pain and tenderness but no tenderness to deep palpation as protected by overlying caecum
Pre/post-ileal → vomiting and diarrhoea from distal ileal irritation
Subcaecal/pelvic → suprapubic pain and urinary frequency
