Appendicitis Flashcards
Name some DDx for RIF pain?
- Mechanical- obstruction, strictures, adhesions, volvulus
- Infectious- appendicits, diverticulitis, gastroenteritis, C diff, hepatitis, pancreatitis, cholecystitis, ischaemic colitis
- IBD- CD (terminal ileum), UC
- Genetic- Hirschsprung’s disease
- Reproductive- ectopic pregnancy, ovarian cyst torsion/rupture, endometriosis, PID
- Urinary- renal calculi, UTI, pyelonephritis, cystitis
- Neoplasia- CRC, ovarian ca, uterine ca
What are the signs of localised peritonism?
- sharp, localised RIF pain,
- guarding
- rigidity
- rebound tenderness
- diminished bowel sounds
What is McBurney’s sign?
Tender RIF
(esp McBurney’s point- 1/3rd distance between ASIS and umbilicus where appendix attaches to caecum)
-> sign of localised peritonism (indicated high risk rupture, need for surgery)
What is Rovsing’s sign?
Compress LIF (stretches/compresses parietal periotenum onto inflamed appendix) -> elicits pain in RIF
What is the Psoas sign?
Pt on left side, extends R thigh slowly (stretch retroperitoneal iliopsoas muscle) -> RIF worsens
Suggests retrocaecal appendix
What is the obturator sign?
Internal rotation of flexed right thigh causes the obturator internus muscle to compresses
appendix -> worsening RIF pain
Suggests pelvic appendix
What are signs of appendiceal perforation?
- tense, distended abdo
- generalised guarding
- sharp, diffuse RIF pain
- absent bowel sounds
- tachycardia
- hypotension
- fever
What are the US findings for appendicitis?
- enlarged appendix (>6mm)
- thickened appendix wall
- peri-appendicular fluid
- faecoliths (concentrated faeces) obstructing lumen
Note: US 60% sensitive
What are the appendicitis CT findings?
- marked fat stranding in peri-appendiceal region
- peri-appendicular fluid accumulation
- lack of gas bubbles in appendix (blockage)
Describe the pathogenesis of appendicitis?
- Obstructed appendix lumen (faecolith, lymphoid hyperplasia, foreign body, GIT worm, tumour)
- mucus build up, acts as bacterial growth medium
- stimulates visceral afferent stretch fibers -> visceral umbilical pain
- venous drainage blocked -> further swelling
- outer serosa inflammed (6hrs) -> parietal peritoneum inflammed -> peritonitis (localised pain)
- bowel irritation (parlaytic ileus and fluid sequestration -> hypovolaemic shock)
- arterial supply occluded -> ischaemia -> perforation
- bacterial leaks -> localised abscess -> bacterial peritonitis -> sepsis and death
Appendicitis risk factors?
Non-modifiable: age (teens, late 40s), male
Modifiable: smoking, low fibre diet
List some complications of untreated appendicitis?
Acute:
- perforation
- peritonitis -> septic shock
- appendicular mass (SB and omentum cover inflated appendix)
- appendicular abscess (unresolved appendicular mass enlarges)
- paralytic ileus -> fluid sequestration -> hypovolaemic shock -> death
Subacute:
- infection drains to liver -> liver abscess
Chronic:
- adhesion formation -> bowel obstruction
How would you manage appendicitis?
- Fluid resuscitation
- Surgery: laparoscopic if not perforated, open if perforated
- Abx: Ampicillin + Gentamicin + Metronidazole
Describe the surface and internal landmarks of the appendix.
• Surface landmark: McBurney’s point- 1/3rd distance between the ASIS and umbilicus (most common attachment point of appendix base to caecum)
• Internal landmarks:
- 2cm inferior to ileocaecal valve
- convergence point of the three taenia coli (converge to form complete longitudinal muscle coat)
Describe the function of the appendix?
- vestigial structure
- contains GIT lymphoid tissue, secretes mucosal IgA
- safe haven for commensal intestinal bacteria during GIT infection (gastro), allowing later repopulation
What are the differing appendix positions? How do these present differently?
1) Retrocecal (43%)- behind caecum or lower ascending colon
Clinical: flank or back pain, worsened by psoas sign
2) Pelvic (9%)- descending into pelvis and suspended over pelvic brim
Clinical: suprapubic pain, dysuria, tenesmus, rectal mass, worse with obturator sign, LLQ (if long)
3) Subcecal- below cecum and pointing to inguinal canal
4) Paracecal
5) Pre-ileal
6) Post-ileal
Clinical: testicular pain (irritates spermatic a. or ureter)
Describe the vascular supply and drainage of the appendix?
Arterial supply:
Ileocolic artery -> appendicular artery (terminal branch)
Venous drainage:
Appendicular vein -> ileocolic vein -> superior mesenteric vein -> portal vein -> sinusoids in liver -> hepatic veins -> IVC
Why does appendicitis pain migrate from the umbilicus to the RIF?
Visceral: appendix and umbilicus innervated by T10 sympathetic fibres
-> appendiceal stretching felt in umbilical region (T10 dermatome)
Parietal: inflammation spreads to outer serosa -> spreads to parietal peritoneum -> local nociceptive fibres stimulated -> localised RIF pain
Describe L1 innervation?
- partial innervation of psoas major and quadratus lumborum
- part of lumbar plexus -> iliohypogastric (T12-L1), ilioinguinal (L1) and genitofemoral (L1-2) nerves
Describe the lumbar plexus?
Lumbar plexus:
- Iliohypogastric (T12-L1):
- Motor: interval and transverse abdominis muscles
- Sensory: lateral gluteal region - Ilioinguinal (L1):
- Motor: internal oblique, transverses abdominis muscles
- Sensory: upper and medial thigh, scrotum and root of penis (males), mos pubis and labia majora (females) - Genitofemoral (L1-2):
- Motor: cremasteric muscle
- Sensory: upper anterior thigh, scrotum (males), mons pubis (females)
