Appendicitis

Appendicitis presents similarly in children and in adults, so it is difficult to separate the two age groups out entirely...so I'm not going to try too hard to do so! The important thing to remember is that atypical signs can lead to late presentations in children (and the elderly).

Pathophysiology


Initially the visceral pain is felt. This is vague, colicky, and in the midline. The appendix is embryologically a mid-gut organ, so pain in the appendix activates sympathetic fibres which enter the spinal cord at T10. This is why the pain is referred to the peri-umbilical area.

Later, somatic pain is felt. This is more constant, and more local. The peritoneum is innervated by the intercostal nerves.

Clinical Features

The Alvardo score can be useful for scoring appendicitis to see whether you think this is low risk. I've rarely seen this used in clinical practice but occasionally use it if the surgical SHO is being difficult and requesting bloods for a barn door appendix. 

M=Migration of pain to RIF             (1)

  (McBurney’s point which lies 1/3 of the way along an imaginary line from the anterior superior iliac spine to the umbilicus and indicates where the inflamed appendix normally lies.)

A=Anorexia                                     (1)

N=Nausea and vomiting                   (1)

T=Tenderness in RIF                        (2)

R=Rebound pain                              (1)

E=Elevated temperature                   (1)

L=Leukocytosis                               (2)

S=shift of WBC to left                      (1)

TOTAL                                          /10

 

 

All factors are quite useful. Anorexia is present in 80% of patients with anorexia.

Rovsing’s sign- press deeply in the LIF for 30s, release suddenly, patient experiences rebound tenderness in RIF.
Psoas sign- ask patient to lift flexed thigh against your hand placed just above the knee, patient experiences pain in RIF
PR: recent evidence suggests a painful PR exam is of little benefit with positive and negative predictive values of 0.44 and 0.54 respectively. Thankfully even the surgeons don't often ask for PRs in kids!



Investigations
Up to 30% of patients with appendicitis will have an abnormal urinalysis.
Plain abdominal x-ray has no role.  

USS has accuracy of about 90% (sensitivity 84% and specificity 88%)

CT has a greater overall accuracy of 94% (sensitivity 94%, specificity 95%) 

In children, USS is likely to be as good as CT.

 

 

 

http://www.enlightenme.org/knowledge-bank/cempaedia/appendicitis
http://www.enlightenme.org/learning-zone/appendicitis-or-not
http://learning.bmj.com/learning/module-intro/acute-surgical-abdomen-children.html?moduleId=10015305&searchTerm=%E2%80%9Cappendicitis%E2%80%9D&page=1&locale=en_GB
http://calgaryguide.ucalgary.ca/slide.aspx?slide=Appendicitis.jpg
http://www.mdcalc.com/alvarado-score-for-acute-appendicitis/