Appendicitis is the most common indication for abdominal surgery in children.
About 5% of the population will have appendicitis at some point
Most commonly occurs in the 2nd and 3rd decades, but can occur at any age. There are two peaks of incidence – in the 2nd and 3rd decade, and again in the elderly.
Appendicitis in the Elderly
- Approx 10% of cases occurs in the over 60s
- About half of cases will not have fever or a raised WCC
- Delayed diagnosis is common
- Perforation rate is 5x higher
- Much higher mortality – up to 50% – probably because of the above factor
Appendicitis in pregnancy
- Occurs in 1/1000 pregnancies
- This is not more common than the general population, however, it carries a greater risk of mortality
- Risk of mortality is greatest after 20 weeks gestation
- Perforation occurs in 15-20% of cases
- Fetal mortality without perforation – 1.5%
- Fetal mortality with perforation – 20-30%
- As pregnancy advances, the position of the appendix changes, thus pain is usually poorly localised, and signs of peritonitis are usually less obvious
- If appendicitis is suspected in pregnancy is should be investigated quickly with laparotomy by an experienced surgeon
Once obstructed, there can be:
- Bacterial overgrowth
If untreated, there may be:
- Sometimes, this is contained by the greater omentum, in which case, and appendical abscess may form
Pain – typically episgastric or periumbilical, before localising to the RLQ
- Pain migration occurs due to the different innervations of the layers. The viscera (i.e. the appendix tissue itself) is innervated by the splanchnic nerves, which are poorly localising, and localise to the centre of the abdomen. Once the peritoneum becomes involved, different nerve pathways are activated, and the pain can be more closely localised. These differences are due to the different embryological derivations of the layers of the gut.
- Peritonitis if present– classic peritonitis pain of washboard rigidity – as the pain is exacerbated by the slightest movement (e.g. rolling, coughing, even breathing)
- Rebound tenderness at McBurney’s point – press at this point does not elicit pain, but relieve the pressure (the ‘rebound’) elicits pain (or elicits more pain than the initial pressing)
- Mcburney’s Point –2/3’s of the way along an imaginary line from the umbilicus to the anterior superior iliac spine on the right hand side
- Rovsing’s Sign – pain felt in the LRQ when the LLQ is palpated
- Psoas sign –increased pain during passive extension of the right hip
- Obturator sign –pain felt on passive internal rotation of the flexed hip
Low grade fever
The above classical symptoms only appear in <50% of patients. There are lots of other presentations!
- Pain is less likely to be localised in children
- Bowel movements – often less frequent, or absent especially if peritonitis is present
- Urine dipstick – may show WBCs and/or RBCs
If classical signs / symptoms are present, then diagnosis is often clinical
- Delaying diagnosis in these patients can be life-threatening – delaying treatment increases the risk of perforation and peritonitis
- The Alvarado Score is a way of scoring suspected appendicitis clinically to identify those who may need surgery. BUT in trials, it has proved no more effective than good clinical judgement. However, it may still be useful when making assessment
- Alvarado score more accurate in Men and Children
Alvarado Score for Appendicitis
Nausea / Vomiting
WCC > 10x109 / L
Neutrophil Count >75%
- <4 – appendicitis unlikely
- 5-6 – observe
- >7 – operate
- Contrast CT – is useful, but can take time to organise. Good sensitivity and specificity, and able to diagnose other differentials – however carries a high radiation dose and is not suitable in children and should be avoid in young people – especially young women – due to irradiation of the ovaries. May miss early appendicitis and / or small appendix.
- USS – can identify appendicitis, but not good at identifying other causes. Often early appendicitis is missed, and it can be inconclusive – if the appendix can’t be seen – usually due to overlying bowel gas – then appendicitis can’t be ruled out
- Laparatomy – don’t be afraid to perform a diagnostic laparotomy if necessary
APPENDICECTOMY! (or appendectomy if you are American) – don’t be afraid to treat quickly. Delaying treatment increases mortality. The negative appendectomy rate is about 10%
- Contraindicated in IBD involving the caecum. Also may be unsuitable in very elderly or severely ill patients.
- In patients who can’t undergo surgery, IV antibiotics are beneficial. They are not curative, but reduce mortality by 50% and thus buy some time.
- Perforation ± peritonitis
- Abscess formation