Integrated my notes into what was already there, feel free to edit, correct or share
Epidemiology: Most common surgical emergency, most common abdominal procedure in the United States. 6% lifetime incidence, just over 1 case per 1000 people per year. Less common in the developed world and children under the age of two, mortality is rare.
Pathophysiology: Caused by an obstruction of the appendiceal luminal obstruction, generally by a fecalith (accumulation and inspissation of faecal matter around vegetable fibres). Enlarged lymphoid tissue or stool are other potential sources of blockages. This blockage causes an increase in pressure leading to luminal bacteria invading the walls of the appendix causing gangrene and eventually perforation.
Risk Factors: Include <6 months breastfeeding, low dietary fibre, improved personal hygiene and smoking
Symptoms: The classic symptoms of appendicitis are periumbilical pain which will later migrate to the lower right quadrant, typically at McBurney's point (one third of the way between superior iliac spine and the umbilicus). 40% of patients will notably not have these symptoms, this can be linked to different anatomical positions of the appendix. The patient will have either a normal temperature or slightly raised. A raised temperature is a red flag for perforation. Other signs include tacycardia, guarding, rebound tenderness, Rosvig's Sign (palpation of the left lower quadrant increases the pain in the right lower quadrant), coughing becomes painful, psoas test (extend the thigh of a patient with a flexed knee either passive or active, will cause pain if the inflammed appendix is in the retrocecal orientation)
Differentials: Common differential diagnoses include ectopic pregnancy, mesenteric adentitis, pelvic inflammatory disease, UTI, cholecystits.
Investigations: Commonly an abdominal ultrasound is the most common diagnostic test. This can be paired with standard bloods with a ptoential Beta HCG to rule out pregnancy. If the patient undergoes a CT (controversial to my understanding but it is done sometimes as a way of ruling out other things) the appendix will be thickened. Exploratory surgery can also be done after a clinical diagnosis.
Treatment: Strictly involves no antibiotics (as it will mask a preforation) and needs to be operated on quickly. Traditionally it is considered to operate on 15-20% of patients with normal appendixes (aka people with a different diagnosis) but in these situations the appendix should be removed to avoid confusing future clinicians in case they get appendicitis in the future but they have an an appendectomy scar. Can be done open or Laparoscopically