Pathophysiology

• Obstruction of appendiceal lumen (e.g. fecalith), occluding small supplying blood vessels → thrombosis, ischemia

Natural history

• Progresses from simple appendicitis to suppurative, gangrenous, perforation, abscess (can correlate to # days of pain)
• Appendicitis in young children more frequently perforated bc they cannot voice specific pain → leads to delayed diagnosis

• McBurney's point = 2/3 of way between umbilicus and ASIS

Alvarado score = likelihood of acute appendicitis based on clinical features

• ≤ 4: appendicitis unlikely
• 5-6: possible appendicitis
• 7-8: probable
• ≥ 9: definite

• Imaging characteristics of appendicitis (US, CT)
• Non-compressible (on ultrasound)
• Dilation > 6 mm
• Mesoappendiceal fat stranding
• +/- fecalith
• free fluid, abscess

Stages of appendicitis

• Simple - lap appy (vs non-op?)
• Perforated - surgery vs IV abx for 5 days
• Perc drainage if needed. Dc when afebrile, asx, tolerating PO. INterval appy in 6 wks. ~ 60% chance recurrence?
• If sure is appendicitis, start IV abx. If unsure, hold off.
• Don't put 'non-perforated' - can't tell for sure on ultrasound

Laparoscopic appendectomy

• Op note
• Positioning - supine with L arm tucked
• Pre-op abx
• Non-perforated - ceftriaxone + flagyl
• Perforated - Zosyn
• Ports
• Umbilical (5-10 mm 30 degree camera), and one of:
• Suprapubic (make sure pt voids or bladder is decompressed)
• LLQ
• Open incision
• Rocky-Davis incision = transverse incision, should be over point of maximum pain or a palpable mass
• If perforated and peritonitis suspected outside of RLQ, lower-midline incision for washout

1. Identify the appendix - the taeniae coli will converge at the base of the appendix
2. Divide mesentery at base of appendix to isolate the blood supply
3. Ligate blood supply (harmonic vs. stapler)
4. Staple off appendix

**hide**Other situations

• **hide**Neoplasm found 
• **hide**At tip of appendix and < 2 cm - continue with appendectomy
• **hide**At base of appendix (or perforated cecal mass) - R hemicolectomy; resect ileocolic mesentery
• **hide**If carcinoid tumor; do R hemicolectomy if pathologically high-risk (positive margin, lymphovascular invasion, mucosal/mucin production)
• **hide**Appendix base too friable
• **hide**Transect across cecum (preserve ileocolic valve and terminal ileum)
• **hide**Normal appendix
• **hide**Look for other causes - Meckel's diverticulum, ovarian torsion, terminal ileitis

**hide**Carcinoid tumor

• **hide**Indolent, neuroendocrine tumor
• **hide**80% in GI tract, 10% in lung
• **hide**Appendix is most common site of incidentally found carcinoid tumor
• **hide**AIR (appendex > ileum > rectum)
• **hide**Carcinoid syndrome
• **hide**Must have tumor outside of portal circulation (serotonin broken down by liver), i.e. in lung or liver/retroperitoneal mets
• **hide**Flushing, watery diarrhea
• **hide**Carcinoid < 1 cm - 20-30% risk of nodal/liver mets
• **hide**Carcinoid > 2 cm or at base - 30-60% risk of nodal/liver mets