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Comparing the Adult Appendicitis Score (AAS) and the Alvarado Score in Diagnosing Acute Appendicitis

Writer: MaytaMayta

Introduction

Acute appendicitis is a common yet challenging diagnosis in patients presenting with abdominal pain. To aid clinicians, various scoring systems have been developed to assess the likelihood of appendicitis and guide decision-making. Among these, the Alvarado and Adult Appendicitis Score (AAS) are widely used. In this post, we will compare these two scoring systems, highlighting their components, differences, and clinical utility.

The Alvarado Score

The Alvarado Score, established in 1986, is a straightforward tool that combines clinical signs, symptoms, and laboratory findings. It helps clinicians stratify patients into low, intermediate, or high probability of appendicitis, facilitating appropriate management.

Components of the Alvarado Score:

  • Symptoms:

  • Migratory right iliac fossa pain (1 point)

  • Anorexia (1 point)

  • Nausea and vomiting (1 point)

  • Signs:

  • Tenderness in the right lower quadrant (2 points)

  • Rebound pain (1 point)

  • Elevated temperature >37.5°C (1 point)

  • Laboratory Findings:

  • Leukocytosis >10,000/mm³ (2 points)

  • Neutrophilia (shift to the left) >75% (1 point)

Scoring:

  • 0-4 points: Low probability of appendicitis

  • 5-6 points: Intermediate probability (consider observation and further imaging)

  • 7-10 points: High probability (consider surgical consultation)

The Adult Appendicitis Score (AAS)

The Adult Appendicitis Score (AAS) is a more recent tool that also incorporates clinical signs, symptoms, and laboratory findings, including C-reactive protein (CRP) levels. This inclusion aims to improve diagnostic accuracy, particularly in ambiguous cases.

Components of the Adult Appendicitis Score:

  • Symptoms:

  • Migratory right lower quadrant (RLQ) pain (1 point)

  • Anorexia (1 point)

  • Nausea and vomiting (1 point)

  • Signs:

  • Tenderness in RLQ (2 points)

  • Rebound tenderness (1 point)

  • Fever (≥37.5°C) (1 point)

  • Laboratory Findings:

  • Leukocytosis >10,000/mm³ (2 points)

  • Neutrophilia >70% (1 point)

  • C-reactive protein (CRP) >10 mg/L (1 point)

Scoring:

  • 0-4 points: Low probability of appendicitis

  • 5-7 points: Intermediate probability (consider further diagnostic testing)

  • 8-11 points: High probability (consider surgical consultation)

Comparison Table

Criteria

Alvarado Score

Adult Appendicitis Score (AAS)

Symptoms



Migratory RLQ pain

1 point

1 point

Anorexia

1 point

1 point

Nausea and vomiting

1 point

1 point

Signs



Tenderness in RLQ

2 points

2 points

Rebound tenderness

1 point

1 point

Fever

1 point (≥37.5°C)

1 point (≥37.5°C)

Laboratory Findings



Leukocytosis

2 points (>10,000/mm³)

2 points (>10,000/mm³)

Neutrophilia

1 point (>75%)

1 point (>70%)

C-reactive protein (CRP)

Not included

1 point (>10 mg/L)

Total Possible Score

10 points

11 points

Interpretation



Low Probability

0-4 points

0-4 points

Intermediate Probability

5-6 points

5-7 points

High Probability

7-10 points

8-11 points

Clinical Utility and Application

Both the Alvarado Score and the AAS are valuable in emergency and primary care settings for assessing the likelihood of acute appendicitis. Here are some key points on their clinical application:

  • Risk Stratification:

  • Both scores help stratify patients into low, intermediate, and high-risk categories.

  • The AAS, with its inclusion of CRP, may offer slightly improved diagnostic precision.

  • Decision-Making:

  • Low-risk patients (0-4 points) may be managed with observation and follow-up.

  • Intermediate-risk patients (Alvarado: 5-6 points, AAS: 5-7 points) should undergo further diagnostic evaluation, typically with imaging such as ultrasound or CT scan.

  • High-risk patients (Alvarado: 7-10 points, AAS: 8-11 points) should be considered for surgical evaluation and potential appendectomy.

  • Advantages of AAS:

  • The inclusion of CRP in the AAS provides an additional marker of inflammation, potentially enhancing diagnostic accuracy in cases where leukocytosis and neutrophilia alone are inconclusive.

Conclusion

The Alvarado Score and the Adult Appendicitis Score are both effective tools for evaluating patients with suspected acute appendicitis. While the Alvarado Score has been widely used for many years, the AAS offers additional diagnostic value with the inclusion of CRP. Clinicians should use these tools in conjunction with their clinical judgment and available diagnostic resources to ensure accurate and timely management of appendicitis.

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Post: Blog2_Post

Message for International Readers
Understanding My Medical Context in Thailand

By Uniqcret, M.D.
 

Dear readers,
 

My name is Uniqcret, which is my pen name used in all my medical writings. I am a Doctor of Medicine trained and currently practicing in Thailand, a developing country in Southeast Asia.
 

The medical training environment in Thailand is vastly different from that of Western countries. Our education system heavily emphasizes rote memorization—those who excel are often seen as "walking encyclopedias." Unfortunately, those who question, critically analyze, or solve problems efficiently may sometimes be overlooked, despite having exceptional clinical thinking skills.
 

One key difference is in patient access. In Thailand, patients can walk directly into tertiary care centers without going through a referral system or primary care gatekeeping. This creates an intense clinical workload for doctors and trainees alike. From the age of 20, I was already seeing real patients, performing procedures, and assisting in operations—not in simulations, but in live clinical situations. Long work hours, sometimes exceeding 48 hours without sleep, are considered normal for young doctors here.
 

Many of the insights I share are based on first-hand experiences, feedback from attending physicians, and real clinical practice. In our culture, teaching often involves intense feedback—what we call "โดนซอย" (being sliced). While this may seem harsh, it pushes us to grow stronger, think faster, and become more capable under pressure. You could say our motto is “no pain, no gain.”
 

Please be aware that while my articles may contain clinically accurate insights, they are not always suitable as direct references for academic papers, as some content is generated through AI support based on my knowledge and clinical exposure. If you wish to use the content for academic or clinical reference, I strongly recommend cross-verifying it with high-quality sources or databases. You may even copy sections of my articles into AI tools or search engines to find original sources for further reading.
 

I believe that my knowledge—built from real clinical experience in a high-intensity, under-resourced healthcare system—can offer valuable perspectives that are hard to find in textbooks. Whether you're a student, clinician, or educator, I hope my content adds insight and value to your journey.
 

With respect and solidarity,

Uniqcret, M.D.

Physician | Educator | Writer
Thailand

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