The Alvarado score adds eight symptoms, examination findings and laboratory findings used in the assessment of suspected appendicitis. Two findings carry two points each and the other six carry one, making a maximum of ten points. The score organises information; it does not identify the cause of abdominal pain on its own.
This calculator reproduces that point addition and attaches a broad probability label to the total. It expects the findings to have been assessed, rather than asking a visitor to perform an abdominal examination or interpret a blood count without help. New or concerning abdominal pain needs appropriate clinical assessment. Waiting to complete a web form, or getting a low total from uncertain answers, should not delay that assessment.
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How to Use This Calculator
Use the observed clinical information for the same assessment episode. The eight choices should describe one coherent presentation, rather than combining old blood results with unrelated symptoms.
Select Yes or No for each item. Right lower quadrant tenderness and leukocytosis contribute two points each; the remaining positive findings contribute one point each.
Check the laboratory definitions printed on the page. It asks about leukocytosis above 10,000 and a left-shift item labelled above 75% neutrophils. Missing blood results are not established negative results.
Calculate and read the total out of ten. The current page labels 0–4 low probability, 5–6 possible appendicitis and 7–10 high probability with urgent evaluation.
Review the individual selections as well as the sum. The same total can come from different combinations, and the calculator does not incorporate other diagnoses, imaging findings or changes over time.
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Formula Used
Score = 2×right lower quadrant tenderness + 1×temperature + 1×rebound tenderness + 1×pain migration + 1×anorexia + 1×nausea/vomiting + 2×leukocytosis + 1×left shift, where each finding is 1 if present and 0 if absent.
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Variables Explained
Input
Meaning in this calculator
Right lower quadrant tenderness
A clinician-assessed examination finding worth 2 points. It is not interchangeable with any abdominal discomfort.
Elevated temperature
The form uses a threshold label of 37.3°C or 99.1°F and assigns 1 point when selected Yes.
Rebound tenderness
An examination finding worth 1 point, distinct from ordinary tenderness.
Migration, anorexia, nausea or vomiting
Three separate history items, each worth 1 point. Migration refers to the pain moving to the right lower quadrant.
Leukocytosis and left shift
Two laboratory-related items worth 2 and 1 points respectively. Read the stated units and criteria rather than guessing from a total white count alone.
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Worked Example
In a worked scoring example, suppose right lower quadrant tenderness, pain migration, nausea or vomiting and leukocytosis are present. Temperature, rebound tenderness, anorexia and the left-shift item are marked absent. The total is 2 + 1 + 1 + 2 = 6 points. This implementation displays “Possible appendicitis” for that sum.
If rebound tenderness is also documented at the same assessment, one further point makes the total 7 and the displayed category changes. That change illustrates a threshold in the program, not a sudden biological boundary. If every item is present, the total is 2 + 1 + 1 + 1 + 1 + 1 + 2 + 1 = 10. If all are selected No, the total is zero, but selecting No because information is unavailable can create a falsely reassuring number.
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Why Use This Calculator?
The original Alvarado publication describes a clinical scoring approach for suspected acute appendicitis. Its purpose is to support assessment, and its usefulness depends on the setting and patient population. A points total is not a percentage chance: six points does not mean a sixty-percent probability. This page has no age, pregnancy or imaging input, so it cannot adapt its result to those circumstances.
Use the displayed categories as descriptions of the software thresholds. They are not instructions to begin treatment, arrange surgery or dismiss symptoms. In particular, the “Low probability” label does not establish that appendicitis has been excluded. Keep the score attached to the findings and time at which they were assessed, because a changing presentation needs reassessment rather than reliance on a previous total.
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Common Mistakes
Do not treat unknown laboratory information as a documented absence of leukocytosis or left shift.
Do not confuse pain in the right lower quadrant with clinician-assessed tenderness; the score separates history from examination.
Do not count nausea and vomiting as two separate points. They share one item on this form.
Do not use a low total to explain away worsening symptoms or a high total as proof of a single diagnosis.
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Frequently Asked Questions
Why do two findings count twice?
The scoring system assigns two points to right lower quadrant tenderness and two to leukocytosis. Each of the six other findings contributes one. The calculator follows those weights, so eight Yes selections produce ten points rather than eight.
Is there a modified Alvarado option?
This page includes all eight items, including the left-shift criterion. It does not offer a separate modified-score selector. When comparing with another tool or a published study, confirm the version and maximum score rather than assuming all tools named Alvarado use identical inputs.
Can I calculate without a blood count?
You can understand the non-laboratory point contributions, but the complete ten-point score needs both laboratory items. Do not mark them No merely to submit the form. A partial sum and a complete score are different pieces of information and should be labelled accordingly.
Does a score of seven confirm appendicitis?
No. Seven crosses the high-probability threshold used by this implementation. It is not a diagnostic test result, and other causes of abdominal pain still require consideration. Clinical decisions depend on examination, investigation and the broader presentation, rather than this number alone.
Why should I record when the score was taken?
The inputs describe a presentation at a particular time. Symptoms, examination findings and blood results can change. Keeping the date and relevant assessment details alongside the score prevents an old total from being mistaken for a current assessment.
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