Calculate the Alvarado (MANTRELS) score to assess appendicitis probability. Evaluates symptoms, signs, and lab values to stratify low, intermediate, and high risk.
The Alvarado Score Calculator (also known as the MANTRELS score) helps clinicians assess the probability of acute appendicitis based on clinical symptoms, physical examination findings, and laboratory results. Developed by Dr. Alfredo Alvarado in 1986, this scoring system remains one of the most widely used clinical decision tools for evaluating right lower quadrant abdominal pain.
The acronym MANTRELS represents the eight criteria: Migration of pain, Anorexia, Nausea/vomiting, Tenderness in RLQ, Rebound pain, Elevated temperature, Leukocytosis, and Shift to the left. Each criterion is weighted based on its diagnostic significance, with RLQ tenderness and leukocytosis receiving 2 points each and all others receiving 1 point, for a maximum score of 10.
This calculator provides instant risk stratification into low (1-4), intermediate (5-6), and high (7-10) probability categories, helping guide decisions about observation, imaging, and surgical consultation while reducing unnecessary appendectomies and missed diagnoses. Check the example with realistic values before reporting.
Acute appendicitis is the most common surgical emergency worldwide, affecting approximately 7% of the population. Delayed diagnosis increases perforation risk, while over-diagnosis leads to unnecessary surgery. The Alvarado score helps standardize clinical assessment and guides appropriate use of imaging resources.
Using this calculator supports evidence-based clinical decision-making, particularly in settings where CT imaging may not be immediately available or where reducing radiation exposure is a priority.
Alvarado (MANTRELS) Score: • Migration of pain to RLQ = 1 point • Anorexia = 1 point • Nausea/Vomiting = 1 point • Tenderness in RLQ = 2 points • Rebound pain = 1 point • Elevated temperature ≥37.3°C = 1 point • Leukocytosis >10,000 = 2 points • Left shift >75% neutrophils = 1 point Total: 0-10 points
Result: 10 / 10 — High Risk (78-82% likelihood)
A patient with all criteria positive scores 10/10, placing them firmly in the high-risk category. Surgical consultation for likely appendectomy is strongly recommended.
Dr. Alfredo Alvarado developed this scoring system at the Regional Medical Center of Orlando in 1986 after analyzing 305 patients who presented with RLQ abdominal pain. By weighting clinical features based on their diagnostic importance, he created a practical bedside tool that could stratify patients before the widespread availability of CT scanning.
While CT scanning has become the dominant diagnostic tool for appendicitis in many settings, the Alvarado score remains valuable for initial risk stratification, determination of imaging urgency, resource-limited settings, and reducing unnecessary imaging in low-risk patients. It also serves as an important teaching tool for clinical reasoning.
Several alternative and complementary scoring systems exist, including the Appendicitis Inflammatory Response (AIR) score, the Adult Appendicitis Score, and the RIPASA score developed for Asian populations. Each has different sensitivities and specificities depending on the population studied.
A score of 7-10 strongly suggests appendicitis and typically warrants surgical consultation. However, current practice usually includes CT imaging confirmation before appendectomy to reduce negative appendectomy rates.
The Alvarado score has a sensitivity of approximately 94-99% for scores ≥5 and specificity of 58-82%. It performs well as a screening tool to identify patients who need further workup, but imaging is usually recommended for definitive diagnosis.
The Alvarado score can be applied to children, though the Pediatric Appendicitis Score (Samuel score) may be more appropriate for patients under 15 years. Children under 3 are particularly challenging as they present atypically.
A score of 1-4 makes appendicitis unlikely (<30%) but does not completely exclude it. Patients with low scores but persistent symptoms should return for re-evaluation. Serial examinations can improve diagnostic accuracy.
The Alvarado score has lower specificity in women of reproductive age due to gynecological conditions that can mimic appendicitis (ovarian cysts, ectopic pregnancy, PID). Imaging is particularly important in this population.
The Modified Alvarado Score (also called the MASS) omits the left shift criterion, making it a 9-point score. This modification was made because the left shift is not always readily available and adds minimal diagnostic value beyond the WBC count.