Appendicitis
Introduction
Appendicitis is the most common cause of acute lower abdominal pain requiring surgical treatment.
It can occur at any age, however it is rare below the age of 2 years and is uncommon in the elderly. The peak incidence is around 20-30 years of age
Usually it is caused by obstruction of the appendiceal lumen by a faecolith.
Clinical Features
Signs
Signs of sepsis (may or may not be present)
Low grade fever
Tachycardia
Increased RR
Abdominal tenderness
RIF tenderness typically at McBurney’s point
Signs of peritonism
Guarding (voluntary or involuntary)
Rebound tenderness
Generalised rigidity is suggestive of perforation.
Less common signs of peritoneal irritation
Psoas sign – RIF pain on psoas muscle contraction with resisted hip flexion
Rovsing’s sign – Palpation and sudden release in LIF causes pain in RIF
RIF pain on hopping on right leg
RIF pain on coughing
Atypical presentations are common in
Extremes of age
Immunosuppressed patients
Pregnancy (sings may be referred to RUQ)
Obesity.
Appendix can be positioned unusually. E.g. retrocaecal
Symptoms
Pain
Initially referred and poorly localised to the abdomen
Later localised to RIF at McBurney’s point (1/3rd of the way from the ASIS to umbilicus)
GIT Symptoms
Anorexia (common)
Nausea/vomiting
Urinary Symptoms
Mild dysuria if the inflamed appendix is adjacent to the urinary system
Complications
Abscess formation
Perforation with peritonitis
Septicaemia.
Differential Diagnosis
Gastrointestinal
Meckel’s diverticulitis
Crohn’s disease
Ileitis
Hernia
Caecal diverticulitis
Colitis
Malignancy
Other
Mesenteric adenitis
Non-specific abdominal pain
Gynaecologic
Ectopic pregnancy
Ovarian cyst
Ovarian torsion
Mittelschmerz (ovarian follicle rupture)
PID
Urologic
Testicular torsion referred pain
Ureteric colic
Pyelonephritis
Clinical Investigations
Appendicitis is a clinical diagnosis. The presentation may sometimes be equivocal or atypical requiring a period of observation or more commonly, in the adult population, cross sectional imaging
Bedside
Urinalysis
Dipstick can aid in excluding UTI (nitrates)
Leucocytes may be detected in some cases of appendicitis
Urinary bhCG is mandatory in all women of child bearing age
Laboratory
FBC – neutrophilia is suggestive but normal WCC doesn’t out rule the dx
CRP – elevated level is suggestive but normal doesn’t out rule the dx
U&E, BM, LFT, Amylase – help out rule other diagnoses
Radiology
Ultrasound – can be useful but appendix only visualised in <50% of cases
Useful to out rule gynaecologic pathology in women
CT Abdomen – sensitivity and specificity of ~ 98%
Disadvantages = cost, availability, radiation exposure
MRI abdomen – used to make the diagnosis in pregnant patients
Clinical Decision Rule
Alvarado score (MANTRELS criteria)
uses a combination of symptoms, signs and laboratory findings to calculate the likelihood of appendicitis
Management & Disposition
Initial Resuscitation
Iv access and fluids as clinically indicated
Disposition
Refer all suspected cases to the surgical team on call
In less suspicious cases patients may be discharged (if well) and advised to return if any deterioration
Symptomatic Treatment
Analgesia as required asap
analgesia may lessen symptoms but does not obscure signs. The diagnosis can still be made post analgesia
Anti-emetic as required
Specific Treatment
If septic consider broad spectrum abx that provide gram negative and anaerobic cover as per local guidelines
e.g. IV Co-amoxiclav + IV Metronidazole
Nil orally
Definitive treatment = laparoscopic appendicectomy
References
Chapter 7.10 Acute appendicitis. Textbook of Adult Emergency Medicine, Cameron et al. 4th Ed 2015 p363 – 366.
SJH Prescribers Guide
This blog was written by Dr. Deirdre Glynn and was last updated in October 2020