Alvarado Score Calculator for Acute Appendicitis
Calculate the original 10-point Alvarado/MANTRELS score or the explicit Kalan 9-point modified score from symptoms, measured oral temperature, and WBC.
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About
This Alvarado Score calculator calculates either the original 10-point 1986 Alvarado/MANTRELS score or the explicit 9-point Kalan 1994 modified score for a person with suspected acute appendicitis. It derives the temperature and leukocytosis points from measured oral temperature and WBC using exact unit normalization. [1, 2]
The total and historical source band support structured assessment only. They do not diagnose or exclude appendicitis, determine imaging, request consultation, or select observation, admission, discharge, antibiotics, or surgery.
Formula
Interpretation
Original 0–4: below the original 5-point compatible threshold; this was not a named disease-exclusion category.
Original 5–6 / 7–8 / 9–10: the 1986 paper used compatible / probable / very probable labels. They are historical source labels, not modern diagnoses or action rules.
Modified 0–4 / 5–6 / 7–9: lower / intermediate / higher modified-score ranges, kept separate from the original 10-point labels.
Any total: interpret only with current clinical assessment and the applicable diagnostic pathway.
Alvarado evidence, versions, and limits
What MANTRELS means
The mnemonic represents Migration, Anorexia-acetone, Nausea/vomiting, Tenderness in the right lower quadrant, Rebound pain, Elevation of temperature, Leukocytosis, and Shift to the left. RLQ tenderness and leukocytosis carry 2 points each; the other original items carry 1. The paper’s “anorexia-acetone” indicant could be satisfied by anorexia, urinary acetone, or both—it did not require urine ketone testing for every score. [1]
Original versus Kalan modified Alvarado
The original 1986 score has eight items and a maximum of 10. Kalan’s 1994 modified score omits left shift and has a maximum of 9. The models are selected explicitly here; missing left-shift data are never scored as absent and never trigger an automatic model change. Kalan’s small prospective study included 49 patients and reported an unacceptably high false-positive rate in women, so “modified” does not mean currently preferred. [1, 2]
Exact temperature and WBC thresholds
The original temperature point uses oral temperature ≥37.3 °C. Fahrenheit is normalized with °C = (°F − 32) × 5 ÷ 9 before comparison: 99.14 °F equals 37.3 °C exactly, while 99.1 °F is below it. Leukocytosis uses a strict WBC >10,000/µL, equivalent to >10.0 ×10⁹/L; exactly 10,000/µL or 10.0 ×10⁹/L receives 0 points. The reporting laboratory still controls measurement and differential definitions. [1]
Derivation and validation context
The 1986 retrospective study began with 305 hospitalized patients with abdominal pain suggestive of appendicitis; 28 with incomplete information were excluded and 277 were analyzed. The appendicitis cohort included ages 4–80, so the derivation should not be described as adult-only. [1]
A 2011 systematic review found a cut point below 5 highly sensitive as a pooled “rule-out” threshold, but that does not mean zero risk; calibration and performance varied in men, women, and children. [3]
Current diagnostic boundary
WSES 2020 found Alvarado insufficiently specific to positively confirm adult appendicitis and identified AIR and AAS as stronger adult discriminators; pediatric scores should not make the diagnosis alone. ACEP 2023 found pediatric rules may assist risk stratification but should not alone determine that advanced imaging is unnecessary, and found insufficient adult evidence for prediction rules to identify who needs no advanced imaging. [4, 5]
The 2025 WSES edition, published in 2026, describes current diagnosis as combining clinical risk assessment and imaging. A 2025 adult meta-analysis confirms Alvarado remains extensively studied while other scores showed better diagnostic accuracy. Those are separate models, not extra modes in this calculator. [6, 7]
Alvarado versus PAS, AIR, and AAS
PAS is a distinct pediatric score. AIR and AAS are distinct adult appendicitis scores with different variables and evidence. Alvarado totals cannot be converted into any of them, and this page does not calculate PAS, pARC, AIR, AAS, or RIPASA. [4, 5, 6]
References
- Alvarado A. A practical score for the early diagnosis of acute appendicitis. Ann Emerg Med. 1986;15(5):557–564. PMID 3963537. DOI 10.1016/S0196-0644(86)80993-3.
- Kalan M, Talbot D, Cunliffe WJ, Rich AJ. Evaluation of the modified Alvarado score in the diagnosis of acute appendicitis: a prospective study. Ann R Coll Surg Engl. 1994;76(6):418–419. PMID 7702329. PMCID PMC2502264.
- Ohle R, O'Reilly F, O'Brien KK, Fahey T, Dimitrov BD. The Alvarado score for predicting acute appendicitis: a systematic review. BMC Med. 2011;9:139. PMID 22204638. PMCID PMC3299622. DOI 10.1186/1741-7015-9-139.
- Di Saverio S, et al. Diagnosis and treatment of acute appendicitis: 2020 update of the WSES Jerusalem guidelines. World J Emerg Surg. 2020;15:27. PMID 32295644. PMCID PMC7386163. DOI 10.1186/s13017-020-00306-3.
- American College of Emergency Physicians Clinical Policies Subcommittee (Writing Committee) on Appendicitis. Clinical Policy: Critical Issues in the Evaluation and Management of Emergency Department Patients With Suspected Appendicitis. Ann Emerg Med. 2023;81(6):e115–e152. DOI 10.1016/j.annemergmed.2023.01.015.
- Alvarez-Lozada LA, et al. Clinical scores for acute appendicitis in adults: A systematic review and meta-analysis of diagnostic accuracy studies. Am J Surg. 2025;240:116123. PMID 39667296. DOI 10.1016/j.amjsurg.2024.116123.
- Podda M, et al. Diagnosis and Treatment of Acute Appendicitis: 2025 Edition of the World Society of Emergency Surgery Jerusalem Guidelines. JAMA Surg. 2026;161(3):283–295. PMID 41604201. DOI 10.1001/jamasurg.2025.6218.
FAQ
MANTRELS represents Migration of pain, Anorexia-acetone, Nausea or vomiting, Tenderness in the right lower quadrant, Rebound pain, Elevation of temperature, Leukocytosis, and Shift to the left. RLQ tenderness and leukocytosis contribute 2 points each; the other original criteria contribute 1 each.
Sources: [1]
The source criterion is oral temperature at least 37.3 °C. Exact conversion makes 99.14 °F equal to 37.3 °C, while 99.1 °F is slightly below that source-Celsius threshold. The calculator compares the exact normalized value before display rounding.
Sources: [1]
The original criterion is WBC strictly above 10,000/µL, equivalent to above 10.0 ×10⁹/L. Exactly 10,000/µL or 10.0 ×10⁹/L does not satisfy this strict threshold; a value above it adds 2 points.
Sources: [1]
Left shift is the eighth original criterion; the 1986 paper gave neutrophils above 75% as an example. Laboratory definitions and reporting can differ. If the criterion is unavailable, the original 10-point score cannot be completed and the calculator will not silently score it as absent.
Sources: [1]
No score creates zero risk. A 2011 review found the below-5 cut point highly sensitive in pooled validation, but performance and calibration varied. Current WSES and ACEP guidance does not support using the score alone to confirm appendicitis or make a universal no-imaging decision.
Disclaimer
Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.