Acute appendicitis in non pregnant adults
Step 1: Pathway Entry
Symptoms to consider: Abdominal pain (RLQ typical but not always the case), nausea, anorexia and vomiting
Appendicitis may present atypically with indigestion, flatulence, bowel irregularity, diarrhoea, malaise
Signs to consider: Low grade fever, Tenderness/ guarding/ rebound in RIF, Rosving’s sign
Step 2: Is the patient stable?
Initial resuscitation if unstable. The patient with acute appendicitis is usually stable, but may present in shock/ multi-organ failure from perforation or sepsis.
Differentials to consider in the unstable patient are sepsis from UTI/ diverticulitis, perforated viscus, gut ischaemia, ectopic pregnancy in women of childbearing age, ruptured AAA in older patients. Bedside ultrasound indicated if AAA is a differential.
Step 3: Detailed initial assessment
In the stable patient a thorough assessment is the next step including a detailed history, a detailed examination, blood tests including FBC, EUC, LFTs, BSL and urinalysis. Do a pregnancy test in women of childbearing age. Lipase if pancreatitis is a differential. Differential diagnoses to think about include testicular torsion in the male, ectopic pregnancy and PID in females, caecal diverticulitis and incarcerated/ strangulated groin hernias. If an alternative diagnosis is made at this time then the steps further down the pathway can be curtailed.
The Alvarado score (mnemonic MANTRELS) is validated for the diagnosis of appendicitis in adults.
M: Migration of pain to right lower quadrant = 1 point
A: Anorexia = 1 point
N: Nausea and vomiting = 1 point
T: Tenderness in right lower quadrant = 2 points
R: Rebound tenderness = 1 point
E: Elevated temperature = 1 point
L: Leukocytosis = 2 points
S: Shift of WBC count to left = 1 point
Appendicitis is probable with a score of 7 or more and is unlikely with a score of less than 4. Patient with a score of 4-6 should have further imaging.
Step 4: Imaging
Imaging is not required in patients with the classic history and physical findings of acute appendicitis. Diagnostic imaging should be performed when the diagnosis of appendicitis is clinically suspected but unclear.
AXR is not indicated in the diagnostic workup of appendicitis, however if an AXR is done it may show right lower quadrant appendicolith, localized right lower quadrant ileus, loss of the psoas shadow, deformity of caecal outline, right lower quadrant soft tissue density
Ultrasound is the first line test in young patients and pregnant women as it does not expose the patient to radiation or contrast. Pelvic ultrasound is useful where gynaecological pathology is a differential. The ultrasound may be inconclusive, unhelpful in obese patients and is operator dependent. An equivocal ultrasound should be followed by a CT or close observation.
Options for CT imaging in appendicitis include CT with contrast and non-contrast CT.
o CT with IV and oral contrast is preferred when CT imaging is indicated. Sensitivity and specificity of up to 98 and 93 percent have been reported. It is useful in making an alternative diagnosis for the patient’s presentation. However it exposes the patient to radiation and contrast. Oral contrast may be omitted where the patient is unable to tolerate oral contrast.
o Non-contrast CT is useful where there is a contraindication to contrast. It is however less helpful in making an alternative diagnosis.
o Podcast discussing CT with or without contrast in appendicitis is available here.
- ACEM Guidelines on Diagnostic Imaging (G126): Flowchart 2.2 - non-traumatic acute right iliac fossa (RIF) or pelvis pain (See page 4/12)
Step 5: Management
Appendectomy remains standard of care. IV antibiotics should be given.
Medical management with antibiotics only (as in diverticulitis) is currently being investigated as a therapeutic option in patients with uncomplicated appendicitis.