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Case 3.2 – Appendicitis

Category: Surgery | Discipline: Surgery - General | Setting: Hospital

Case

Lisa Chan, aged 17 years presents with a 4 hour history of central abdominal pain that has recently localised to right lower abdomen. She feels nauseous but has not vomited. Her bowels have not opened for a day and she feels hot and sweaty.

Questions

1. What is your differential diagnosis (list only 5 options)?

Differential Diagnoses for Right Lower Quadrant Pain:

  • Acute appendicitis
  • Gastroenteritis/mesenteric adenitis/inflammatory bowel disease/Meckel's diverticulitis/acute ileitis
  • Pelvic inflammatory disease (PID)
  • Pyelonephritis/urinary tract infection or stones
  • Hepatitis/cholecystitis
  • Right lower lobe pneumonia
  • Endometriosis/ovulatory pain (Mittelschmerz)/ruptured or haemorrhagic ovarian cyst/ectopic pregnancy
2. If on examination Lisa was found to have a temperature of 37.8° C, halitosis, clinical dehydration, and tenderness (with rebound) over the right iliac fossa, what laboratory investigations would you order to support a diagnosis of acute appendicitis?

Laboratory Investigations:

  • FBC including differential - elevated WCC with neutrophilia suggests bacterial infection
  • CRP - inflammatory marker, typically elevated in appendicitis
  • U&E (Urea & Electrolytes) - assess hydration status and renal function
  • CMP (Comprehensive Metabolic Panel)
  • BHCG (Beta-human chorionic gonadotropin) - pregnancy test (essential in females of reproductive age to rule out ectopic pregnancy)
  • Urinalysis - dipstick and MSU (mid-stream urine) to exclude UTI/pyelonephritis
  • Urinary & gynaecological evaluation (history & examination)
  • Abdominal/pelvic ultrasound - can visualize appendix if inflamed, also useful to exclude gynaecological causes

Clinical Features Present:

  • Temperature 37.8°C (low-grade fever)
  • Halitosis (bad breath)
  • Clinical dehydration
  • Tenderness with guarding & rebound over right iliac fossa (peritonitis)
3. What is the pathophysiology of acute appendicitis?

Pathophysiology of Acute Appendicitis:

1. Initial Obstruction:

  • Obstruction of the appendiceal lumen - being an unpaired midgut structure, pain is characteristically felt in the umbilical region (in the midline)
  • Lymphoid hyperplasia (60% of cases) is the most common aetiology of luminal obstruction
  • Faecolith (35% of cases) - hardened stool causing obstruction
  • Viral illnesses that elicit lymphoid hyperplasia are a frequent prodrome to onset of appendicitis in the young (children)

2. Progressive Inflammation:

  • Oedema and distension in the appendix itself leads to outflow obstruction, continued inflammation, mucous production
  • Vascular compromise - compromise of venous then arterial supply leading to ischaemia and possibly necrosis
  • Bacterial proliferation & toxins

3. Transmural Spread:

  • Transmural spread, serosal inflammation and involvement of parietal peritoneum typically leads to localized right iliac fossa pain
  • This is the characteristic pain migration from central/periumbilical to RIF

4. Potential Complications:

  • As swelling, infection & ischaemia progress, gangrene & perforation is possible
  • Resultant peritonitis may or may not be walled off by greater omentum or other adjacent visceral structures
  • Diffuse widespread peritonitis may occur especially in young patients (who lack well-developed omentum)
4. What structures are encountered with the following surgical incisions: at McBurney's point, midline (upper and lower) abdominal, Pfannenstiel?

Structures at Risk with Surgical Incisions:

McBurney's Point

Located 2/3rds down from line drawn from umbilicus to ASIS (anterior superior iliac spine)

  • Intercostal nerves (but direction of cut avoids this)
  • Inferior epigastric vessels

The oblique incision at McBurney's point is designed to split muscle fibres rather than cut across them, avoiding major nerves and vessels.

Midline (Upper and Lower) Abdominal

  • Linea alba - relatively avascular, therefore minimal risk to vessels or nerves
  • This is why midline incisions are preferred for major abdominal surgery - safest approach

Pfannenstiel Incision

Transverse suprapubic incision (commonly used for C-sections and pelvic surgery)

  • Inferior epigastric vessels - must be identified and avoided/ligated
5. Discuss the indications for open as compared to laparoscopic appendicectomy and the risks and benefits of each approach.

Open Appendicectomy

Benefits:

  • Direction of incision at McBurney's point avoids inferior epigastric vessels and helps avoid dividing lower intercostal and abdominal wall nerves
  • Relatively cost efficient - less equipment required
  • Faster in straightforward cases with experienced surgeon
  • May be necessary in cases with significant adhesions or complicated anatomy

Risks:

  • Larger wound, more postoperative pain
  • Higher risk of wound infection
  • Longer recovery time
  • More prominent scarring

Laparoscopic Appendicectomy

Now considered standard of care

Benefits:

  • Less chance of wound infection in routine cases
  • Useful in cases of diagnostic uncertainty - can visualize entire abdomen and pelvis
  • Less post-operative pain
  • Shorter length of stay - 1 night in uncomplicated cases vs 2-3 days
  • Better cosmetic outcome (3 small incisions)
  • Faster return to normal activities
  • Better visualization of pelvic organs (especially important in females)

Risks:

  • Possibly increased risk of abscess formation in perforated cases
  • Increased cost due to equipment required
  • Requires general anaesthesia and pneumoperitoneum
  • Longer operative time (though improving with experience)
  • Risk of trocar injury to vessels or bowel

Indications

Laparoscopic is now preferred in most cases, especially:

  • Young females (diagnostic uncertainty for gynae causes)
  • Obese patients
  • Diagnostic uncertainty

Open may be preferred in:

  • Pregnancy (though laparoscopic can be done in 1st/2nd trimester)
  • Known extensive adhesions
  • Haemodynamic instability
  • Resource-limited settings
6. Discuss the key steps in the post operative management of a person following an open appendicectomy.

Key Steps in Post-Operative Management:

Immediate Post-Operative Care

  • IV fluids continued until patient tolerating oral intake
  • DVT prophylaxis - low molecular weight heparin, TED stockings
  • Chest physiotherapy and early mobilization to prevent respiratory complications
  • Analgesia - regular paracetamol +/- opioids as needed

Antibiotic Management

  • Cease IV antibiotics post-op unless the appendix is perforated or gangrenous or there is an associated abscess
  • If frank peritoneal perforation and contamination or abscess found, then antibiotics until patient afebrile and regained GIT function
  • Some will need 3-5 days of antibiotics

Monitoring for Complications

Most common post-op complication is wound infection

Be aware of rare but important complications:

  • Abscess (intra-abdominal, pelvic) - persistent fever, pain, elevated WCC
  • Bleeding
  • Injury to surrounding structures e.g. bowel and ureter
  • Ileus may result if there was significant peritoneal contamination

Follow-Up

  • Histopathology report must be formally followed up - beware of coincident appendiceal tumours (rare but important)
  • Wound review at 1 week
  • Return to normal activities as tolerated (usually 2-4 weeks)

Discharge Criteria

  • Afebrile
  • Tolerating oral diet
  • Pain controlled on oral analgesia
  • Mobilizing independently
  • No signs of complications