This document provides an evidence-based overview of appendicitis, including: 1. The epidemiology of appendicitis, which most commonly affects males between ages 5-50, with a peak incidence in teenagers. 2. The anatomy and pathophysiology of appendicitis, explaining how obstruction can lead to inflammation anywhere along the appendix. 3. Diagnostic tools for appendicitis including physical exam findings, blood tests, scoring systems like the Alvarado score, and imaging like CT scans. History alone rarely provides a classic presentation. 4. Treatment involves IV opioids for pain management but antibiotics alone do not impact postoperative findings, and certain antibiotic classes should be avoided due to high resistance patterns

1. Evidence Based Approach to Appendicitis EBM summary

2. Epidemiology Males>Females @ 1.4:1 (lifetime risk 8.6%, 6.7% respectively) Females have higher negative appendectomy rate Most common between the ages of 5-50 Peak incidence 10-14yo (males) and 15-19yo (females) Risk factors: smoking, low fiber diet, Caucasian ethnicity, summermonths

3. Anatomy Retrocecal>pelvic>subcecal>preilial>postilieal 11% of retrocecal appendices extend into the retroperitoneum Might present as R flank pain Obstruction causes inflammation in 50% of cases and can occur anywhere along the length of the appendix Tip appendicitis is inflammation of the distal-most aspect, common cause of false-negative CT scans McBurney’s Point

4. Pathophysiology 5 Stages of Appendicitis Appendiceal obstruction, luminal distension T8-T10 visceral afferent nerve irritation (periumbilical pain) Lasts 4-6h classically Intraluminal pressure>local venous pressure resulting in tissue ischemia and vascular congestion Ischemia induces inflammation and local bacterial invasion Inflammation extends extraluminally leading to parietal peritoneal inflammation and focal pain

5. Variations on Classic Presentation Perforation rate is 80% if diagnosis is delayed >48h from the onset of pain Recurrent Appendicitis Patient with ≥1 episode of similar pain in the past Subacute/Chronic Appendicitis Abdominal pain lasting days-weeks that is relieved post-appendectomy Delayed presentations often have CT e/o inflammation History of prior abdominal pain has poor NPVfor acute appy

6. Why do I need my appendix, doctor? You can tell your patient one of the following… We really don’t know It served its purpose when you were young helping develop your immune system, but it’s purpose greatly decreased after about the age of 5 years old It acts as a reservoir for commensal bacteria, offering re-inoculation of the colon should all your normal flora be wiped out

7. Differential Diagnosis Enteritis (Yersinia, Campylobacter, Salmonella) Omental infarction (NEC in kids) Epiploicappendigits (mesenteric adenitis in kids) UTI/pyelo Nephrolithiasis Hernia Bowel obstruction Cecaldiverticulits (Meckel’s) Cecal volvulus (intuss in kids) Testicular/ovarian torsion PID/TOA Ruptured ovarian follicle/ectopic pregnancy

8. Physical Examination RLQ TTP (specifically McBurney’s) and rigidity are most predictive of acute appy Rebound, guarding, fever, and psoas sign have additive value Pain on rectal exam, Rovsing’s sign, increased RLQ skin temperature have no diagnostic value Psoas (13-42% sens, 79-95% spec) if performed correctly! Obturator (8% sens, 94% spec)

10. Anorexia/ketonuria (1)

11. Nausea/vomiting (1)

12. TTP to RLQ (2)

13. Rebound tenderness (1)

14. Elevated temp >37.5C (1)

16. Nausea/vomiting (1)

17. Migratory pain (1)

18. Fever > 38C (1)

19. RLQ pain w/ cough/hopping (2)

20. RLQ TTP (2)

21. WBC >10k (1)

22. Bandemia >7500 (1)0-2: Low risk (2% false positive 3-6: Inderterminant >7: High risk (96% specificity)

23. Appendicitis Inflammatory Response Score Shows decent diagnostic value better than Alvarado 73% true negatives and 67% true positives identified Only 37% left indeterminant Alvarado -> 61%, 40%, 48%, respectively Vomiting (1) RLQ Pain (1) RT or Guarding (light (1), medium (2), strong (3)) Temp > 38.5C (1) PMN count (70-84% (1), ≥85% (2)) WBC count (10-14.9 (1), ≥15 (2)) CRP (1-4.9 (1), ≥5 (2)) 0-4: Low Prob (o/p f/u supported) 5-8: Indeterminate (serial exams or further testing required) ≥9: High Prob (surgical exploration proposed)

24. Unique Workup Options Stool guiac Heme-positive diarrhea suggestive of enteroinvasive bacteria UA >30RBC/hpfor >20WBC/hpf suggests UTI>appy Cervical motion tenderness Can be seen with any peritoneal inflammation, non-specific Significant if associated with pelvic discharge WBC + CRP (a fool makes a judgment based on WBC alone!) WBC alone has low diagnostic value WBC>10 and CRP>8 has notable predictive power WBC>15 and PMN>85% is slightly useful

25. Treatment IV opioids DOES NOT mask physical exam findings Antibiotics vs placebo – no difference in post-op findings histologically Augmentin, cefotetan, clindamycin should NOT be considered (high resistance patterns in E.coli and B.fragilis) MRSA coverage not necessary FQs showing rapidly emerging E.coli resistance patterns