The Vermiform Appendix in brief:

Introduction

Acute appendicitis is the most common cause of acute abdomen in young adults
Usually happens on wakening (from experience) or so painful that the patient awakes

Anatomy
The appendix has no peristaltic capabilities
The base of the appendix is constant: the confluence of the 3 taenia coli of the caecum whcih fuse to form the outer longitudinal muscle coat of the appendix
Appendicular artery is an end artery
Location of the appendix: 6 in all
74% (3/4) Retrocecal!
21% (1/5) Pelvic
Others: Paracaecal, subcaecal, preileal, postileal

Acute Appendicitis
Introduction
Rare in infants
becomes increasingly common in childhood
reaching peak in teens and early 20s
after middle age, the risk becomes quite small
at 25 yo, males: females = 3:2 (Bailey and Love)

Aetiology:
Refer to book

Pathology: Refer to Robbins

Clinical Diagnosis
Central abdominal pain (poorly localized, colicky [though less severe than small bowel colic]) a/w nausea, anorexia and usually 1 or 2 episodes of vomiting following onset of pain
The pain is usually relieved with movement (i.e. patient is restless)
Anorexia is useful and constant especially in children
After the next 6 hours, temperature slowly rises with increased HR


Migratory Pain: periumbilical visceral to RIF somatic. this shift is only seen in 50% of acute appendicitis. Recall that for that to occur, the appendix must be anteriorly positioned. Unfortunately, 3/4 of appendices are located retrocecally.
Anorexia: constant feature, especially in children
Nausea/Vomiting: vomiting episodes (1 or 2) usually follow onset of periumbilical pain
Tenderness over RIF: localised somatic pain, worse with movement (peritoneal irritation). Localized pain in RIF is unusual in elderly. Tenderness over the RIF is only possible if the appendix is anteriorly located. In fact people with an appendix in the pelvis may instead present with suprapubic discomfort and tenesmus with tenderness elicited via DRE.
Rebound tenderness
Elevated temperature: slowly rises after 6 hours. Temperatures > 38.5*C in children, suspect other causes e.g. mesenteric adenitis
Leukocytosis
Shift to the Left

Maximal tenderness and guarding over the McBurney's point

Signs: 4 in all
1. Pointing sign (asked to point to where it began and hwere it moved).
2. Rovsing's sign
3. Psoas Sign (Usually the px presents with hips flexed due to retrocecal position of appendix sitting on and irritating the psoas muscle. Extending the hip worsens the pain)
4. Obturator sign: flex hip and internally rotate. This stretches the obturator internus. If irritated by the appendix, the pain will be felt in the suprapubic region.

Special features suggesting location
1. Retrocecal: RIF tenderness may be absent (shielded by cecum). Loin tenderness instead. rigidity of the quadratus lumborum. Psoas sign (flexed hip). Hyperextend only if hips not flexed to start with (i.e. not already in pain)
2. Pelvic: RIF pain may be absent. suprapubic pain just above and to the R of the pubic symphysis, tenesmus, diarrhea (appendix with rectum) or frequency (if in contact with the bladder) DRE = tenderness in POD or rectovesical pouch on the R side. Psoas and obturator sign may be present.
3. Post ileal: diarrhea and retching. Tenderness to the R of the umbilicus.

Special features according to age

Elderly: localized pain in RIF is unusual
Obese
Pregnant

Investigations
Lab:
FBC, U/E/Cr, UPT, Urinalysis
Imaging studies
Abdominal ultrasound
CT scan when met with diagnostic uncertainty

Management:
Alvarado score (for Emergency departments w/o CT scans)
The scores will determine whether or not to request for urgent GS registrar referral
7-10: high risk
4-7: moderate risk
1-3: d/c with advice to return

Treatment
Appendicectomy
Complications
- Rupture
- Appendiceal mass to rupture later
- Abscess
- spread into portal circulation
- Fistula formation