Appendicitis

Question 1

Define appendicitis.

Answer 1

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).

Question 2

How common is appendicitis?

Answer 2

• 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)

Question 3

What is the aetiology of appendicitis?

Answer 3

Obstruction of the lumen of the appendix by…

• faecolith (40%)
• normal stool
• lymphoid hyperplasia
• rarely appendiceal or caecal tumour

Question 4

What are the risk factors for appendicitis?

Answer 4

• 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.

Question 5

Describe the pathophysiology of appendicitis.

Answer 5

• 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.

Question 6

How does pattern of pain progress in appendicitis?

Answer 6

• 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

Question 7

What is a typical presentation of appendicitis?

Answer 7

• 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

Question 8

What are the signs of appendicitis on physical examination?

Answer 8

• 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

Question 9

What clinical scoring system may be used to stratify patients with appendicitis?

Answer 9

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)

Question 10

When will the WCC vs CRP be high in appendicitis?

Answer 10

Leucocytosis within 5-24hrs of symptoms

CRP only raised after >12hrs of symptoms

Question 11

What investigations would you do for acute appendicitis?

Answer 11

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

Question 12

What features on imaging suggest an inflamed appendix?

Answer 12

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

Question 13

What are features of complicated appendicitis?

Answer 13

• Gangrenous appendix with or without perforation
• Intra-abdominal abscess
• Peri-appendicular phlegmon
• Purulent-free fluid

Question 14

How do you manage acute appendicitis?

Answer 14

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.

Question 15

When can you use conservative treatment in appendicitis?

Answer 15

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.

Question 16

What are the possible complications of acute appendicitis?

Answer 16

• Perforation causing peritonitis - more common in >50yr and very young
• Sepsis
• Appendicular mass - due to delay in medical treatment causing appendix to be walled off by omentum to form an inflammatory mass
• Abscess - treat with antibiotics +/- CT-guided drainage. Interval appendectomy is performed after 6 weeks if the symptoms are not completely resolved.
• Bowel obstruction - from perforations and adhesions
• Surgical wound infection

Question 17

What is the prognosis for appendicitis?

Answer 17

Good prognosis

Mortality 0.8 in 1000 for non-perforated appendix and 5 in 1000 for perforated appendix

Question 18

How long is the appendix?

Answer 18

6-10cm

Question 19

What is the purpose of the appendix?

Answer 19

Uncertain

May be a reservoir for gut microbiota as it is highly concentrated with GALT

Question 20

What might a sudden relief of pain sometimes indicate in appendicitis?

Answer 20

Appendiceal perforation

Question 21

Can you get appendicitis after appendicectomy?

Answer 21

Stump appendicitis is possible especially if whole appendix hasn’t been resected

Question 22

How might different anatomical positions of the appendix affect presentation?

Answer 22

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