There are multiple validated decision tools utilized in the diagnosis of appendicitis. These include the Adult Appendicitis Score (AAS), Alvarado, Appendicitis Inflammatory Response (AIR), and RIPASA scoring systems. These scoring systems involve a combination of history, examination findings, and investigation results.
The Alvarado score is commonly used and has undergone the most validation studies. The AIR score performed well in one systematic review of clinical prediction rules. It showed high sensitivity (92%) and specificity (63%) in predicting acute appendicitis. The RIPASA score was more sensitive than the Alvarado score, with improved diagnostic odds ratio, but lower specificity.
The Alvarado score can be used to rule out appendicitis but should not be used to confirm a diagnosis of appendicitis.
The AIR score and the AAS seem currently to be the best performing clinical prediction scores and have the highest discriminating power in adults with suspected acute appendicitis. The AIR and AAS scores decrease negative appendectomy rates in low-risk groups and reduce the need for imaging studies and hospital admissions in both low- and intermediate-risk groups.
Scoring systems can be used to determine the likelihood or rule out the diagnosis of appendicitis in order to guide further investigations and management.
The AIR score or the AAS can be used to determine whether a patient is at high, intermediate or low risk of having appendicitis.
High-risk patients who are aged <40 years, and have strong symptoms and signs of appendicitis, may go straight to surgery without imaging. However, local protocols should be checked as this varies in practice.
Intermediate-risk patients may undergo further imaging and observation.
Low-risk patients may be safely discharged without diagnostic imaging, as long as they have appropriate safety-netting.
Adult Appendicitis Score (AAS)
The higher the score, the greater the chance of having acute appendicitis. This scoring system reliably reduces the need for imaging studies and hospital admissions in both low- and intermediate-risk groups.
Pain in right lower quadrant = 2 points.
Pain relocation = 2 points.
Right lower quadrant tenderness
Women, aged 16-49 years = 1 point.
All other patients = 3 points.
Mild = 2 points.
Moderate or severe = 4 points.
Blood leukocytes (×10⁹/L)
≥7.2 and <10.9 = 1 point.
≥10.9 and <14.0 = 2 points.
≥14.0 = 3 points.
Proportion of neutrophils %
≥62 and <75 = 2 points.
≥75 and <83 = 3 points.
≥83= 4 points.
CRP (mg/L), symptoms <24 hours
≥4 and <11 = 2 points.
≥11 and <25 = 3 points.
≥25 and <83 = 5 points.
⩾83 = 1 point.
CRP (mg/L), symptoms >24 hours
≥12 and <53 = 2 points.
≥53 and <152 = 2 points.
≥152 = 1 point.
Sum ≥16 = high risk.
Sum 11 to 15 = intermediate risk.
Sum 0 to 10 = low risk (further investigation not needed).
Alvarado (MANTRELS) score
Score is based on clinical characteristics of the patients. The higher the score out of a possible total of 10, the greater the chance of having acute appendicitis.
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 Inflammatory Response (AIR) score
Vomiting = 1 point.
Pain in right inferior fossa = 1 point.
Rebound tenderness: light = 1 point; medium = 2 points; strong = 3 points.
Body temperature ≥38.5 = 1 point.
Polymorphonuclear leukocytes: 70% to 84% = 1 point; ≥85% = 2 points.
WBC count: 10.0 to 14.9 ×10⁹/L = 1 point; ≥15.0 ×10⁹/L = 2 points.
CRP concentration: 10 mg/L to 49 mg/L = 1 point; ≥50 = 2 points.
(Maximum 12 points.)
Sum 0 to 4 = low probability. Outpatient follow-up if unaltered general condition.
Sum 5 to 8 = indeterminate group. In-hospital active observation with rescoring/imaging or diagnostic laparoscopy according to local traditions.
Sum 9 to 12 = high probability. Surgical exploration is proposed.
RIPASA Score for Acute Appendicitis
The higher the score out of a possible total of 16, the greater the chance of having acute appendicitis. The scoring system was developed for Asian populations.
Female = 0.5 points.
Male = 1 point.
Age <39.9 years = 1 point.
Age >40 years = 0.5 points.
Right iliac fossa (RIF) pain = 0.5 points.
Migration of pain to RIF = 0.5 points.
Anorexia = 1 point.
Nausea and vomiting = 1 point.
Duration of symptoms <48 hours = 1 point.
Duration of symptoms >48 hours = 0.5 points.
RIF tenderness = 1 point.
Guarding = 2 points.
Rebound tenderness = 1 point.
Rovsing sign = 2 points.
Fever = 1 point.
Raised WBC = 1 point.
Negative urine analysis = 1 point.
(Maximum 16 points.)
Acute Physiology and Chronic Health Evaluation II (APACHE II) score
The APACHE score is commonly used to establish illness severity in the intensive care unit (ICU) and predict the risk of death. [ APACHE II scoring system ] There is a high risk of death if the score is 25 or above.
There are several other models that have been developed for use in the ICU, including APACHE III, Mortality in Emergency Department Sepsis score, Simplified Acute Physiology Score, Sepsis-related Organ Failure Assessment, and Mortality Probability Model II.
Early diagnosis remains challenging in children due to atypical clinical features and the difficulty of obtaining a reliable history and physical examination. In children with suspected acute appendicitis, scoring tools such as the Alvarado score and Samuel’s Pediatric Appendicitis Score (PAS) are useful to exclude appendicitis. The PAS includes similar clinical findings to the Alvarado score in addition to a sign more relevant in children: right lower quadrant pain with coughing, hopping, or percussion. However, diagnosis should not be based on clinical scores alone.
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