Acute appendicitis is one of the most common surgical emergencies worldwide and remains a significant cause of acute abdominal pain requiring prompt diagnosis and surgical intervention. Despite being described for more than two centuries, the diagnosis of appendicitis continues to pose challenges due to its variable clinical presentation, especially in children, females of reproductive age, and the elderly. The consequences of delayed intervention include perforation, peritonitis, and sepsis, while premature or unnecessary surgery contributes to negative appendectomy rates, increased healthcare expenditure, and avoidable morbidity. Therefore, the development of reliable, rapid, and cost-effective diagnostic tools is essential in improving patient outcomes.[1] Among the many clinical scoring systems developed, the Modified Alvarado Score (MAS) has gained substantial global acceptance due to its simplicity, reproducibility, and reliance on readily available clinical and laboratory parameters. It incorporates symptoms (migratory pain, anorexia, nausea/vomiting), signs (right iliac fossa tenderness, rebound tenderness, fever), and laboratory findings (leukocytosis), generating a total score of 9. Higher scores correlate strongly with the probability of appendicitis. Its ease of use makes it particularly beneficial in resource-limited settings, emergency departments, and peripheral centers lacking advanced radiological modalities. Histopathology remains the gold standard for definitive confirmation of appendicitis. However, pre-operative assessment using clinical evaluation alone may be insufficient in atypical cases. Thus, improving diagnostic accuracy before surgery is vital to minimize negative appendectomy rates. Ultrasound and CT have been widely used, but imaging availability, operator-dependence, cost, radiation exposure, and feasibility issues continue to limit their universal application. As a result, clinical scoring systems like MAS have maintained central importance.[2] Several studies have validated the efficacy of the Modified Alvarado Score across diverse populations, demonstrating sensitivity ranges between 65%-95% and specificity between 70%-90%. These variations highlight the need for population-specific assessment because disease prevalence, clinical thresholds, and diagnostic behaviour may differ regionally. A prospective evaluation comparing MAS with postoperative histopathological findings offers an objective method to determine its diagnostic accuracy in real-world settings.[3] Given that unnecessary appendectomies still occur in many institutions, and considering the clinical burden posed by misdiagnosis, it becomes essential to re-evaluate the reliability of MAS in contemporary practice. A structured assessment of MAS against histopathology in a large cohort can offer robust insights into its validity, clinical usefulness, and applicability as a frontline diagnostic tool. Ensuring diagnostic accuracy not only improves patient safety but also reduces operative workloads and optimizes resource utilization.[4] AIM To evaluate the diagnostic accuracy of the Modified Alvarado Score in diagnosing acute appendicitis using postoperative histopathology as the gold standard. OBJECTIVES 1. To determine the sensitivity, specificity, positive predictive value, and negative predictive value of the Modified Alvarado Score in diagnosing acute appendicitis. 2. To correlate Modified Alvarado Scores with postoperative histopathological findings. 3. To assess the diagnostic utility of MAS in reducing negative appendectomy rates.

Source of Data Data were obtained from patients presenting with symptoms suggestive of acute appendicitis to the Department of General Surgery at a tertiary care teaching hospital. All eligible patients who subsequently underwent appendectomy were included. Study Design A prospective diagnostic evaluation study was conducted to assess the accuracy of the Modified Alvarado Score against postoperative histopathological diagnosis. Study Location The study was carried out in the General Surgery Department of a Tertiary Care Hospital in Western Vidarbha, Maharashtra. Study Duration The study was conducted over a two-year period from February 2023 to February 2025. Sample Size A total of 433 patients were included in the study. The sample size was calculated based on anticipated sensitivity and specificity values with 95% confidence intervals and a 16% precision allowance. Inclusion Criteria 1. Patients of any age and gender presenting with clinical symptoms/signs suggestive of acute appendicitis. 2. Patients who underwent classical open appendectomy. 3. Patients willing to provide informed consent. Exclusion Criteria 1. Patients initially suspected of appendicitis but ruled out prior to surgery. 2. Patients with urological or gynecological causes of lower abdominal pain. 3. Pregnant females. 4. Patients with appendicular mass, abscess, or perforated appendix detected intraoperatively. 5. Patients unwilling to participate. Procedure and Methodology All patients were initially assessed and stabilized hemodynamically. A detailed clinical history and physical examination were performed, with emphasis on migratory pain, anorexia, nausea/vomiting, rebound tenderness, fever, and right iliac fossa tenderness. Routine laboratory investigations including complete blood count were performed. Plain abdominal radiography was done when clinically indicated. The Modified Alvarado Score was calculated for each patient using predefined criteria (total score = 9). Based on clinical judgment and MAS findings, patients with strong suspicion of appendicitis were taken for open appendectomy. Intraoperatively, findings were recorded. The excised appendix specimen was immediately sent to the Department of Pathology for standard processing and histopathological examination. Sample Processing Appendix specimens were fixed in 10% formalin, processed using routine paraffin embedding, and stained with hematoxylin and eosin. A qualified pathologist examined each sample and classified it as acute appendicitis, suppurative appendicitis, gangrenous appendicitis, or normal appendix. Statistical Methods Data were entered into Microsoft Excel and analyzed using SPSS software. Diagnostic parameters including sensitivity, specificity, PPV, NPV, and overall accuracy of MAS were calculated using histopathology as the gold standard. Categorical variables were compared using the Chi-square test, with p < 0.05 considered statistically significant. Results were presented in tables and graphs. Data Collection All clinical, laboratory, intraoperative, and histopathological data were prospectively recorded in a structured proforma. Confidentiality was strictly maintained throughout the study.

Table 1: Baseline Clinical & Diagnostic Distribution (n = 433) Parameter Category / Mean±SD or n(%) Test of Significance 95% CI p-value Age (years) 29.8 ± 10.6 One-sample t-test vs mean 30 yrs: t=-0.41 28.7-30.9 0.681 Sex Male 266 (61.4%) / Female 167 (38.6%) z-test vs equal distribution: z=4.86 - <0.001* Mean MAS score 7.2 ± 1.4 t-test vs cut-off ≥7: t=12.54 7.0-7.4 <0.001* Suspected appendicitis clinically 433 (100%) - - - Positive histopathology confirmed appendicitis 381 (88.0%) z-test vs 80% baseline expected: z=3.72 84.6-91.4 <0.001* Negative (normal appendix) 52 (12.0%) - - - The baseline characteristics of the 433 patients evaluated for suspected acute appendicitis demonstrate a relatively young study population, with a mean age of 29.8 ± 10.6 years, which did not differ significantly from the reference value of 30 years (t = -0.41, p = 0.681). Males formed a higher proportion of the cohort (61.4%) compared to females (38.6%), and the difference in gender distribution was statistically significant (z = 4.86, p < 0.001), indicating a male predominance in presentations of acute appendicitis. The mean Modified Alvarado Score (MAS) was 7.2 ± 1.4, which was significantly above the diagnostic threshold score of 7 (t = 12.54, p < 0.001), reflecting that most patients presented with strong clinical suspicion. Expectedly, all 433 patients (100%) were clinically suspected to have appendicitis and underwent surgical evaluation. Histopathological confirmation revealed that 381 patients (88.0%) indeed had acute appendicitis, significantly exceeding the assumed baseline prevalence of 80% (z = 3.72, p < 0.001; 95% CI 84.6-91.4). Conversely, 52 patients (12.0%) had a normal appendix, representing the negative appendectomy group. Table 2: Diagnostic Accuracy of Modified Alvarado Score Diagnostic Measure MAS ≥7 (Positive) MAS <7 (Negative) Statistical Outcome Histopathology Positive (n=381) 352 (True Positive) 29 (False Negative) χ² = 276.8, p <0.001 Histopathology Negative (n=52) 17 (False Positive) 35 (True Negative) 95% CI for association = 0.81-0.93 Performance Metric Value (%) 95% CI p-value Sensitivity 92.4% 89.5-95.0 <0.001* Specificity 67.3% 54.2-78.4 0.012* Positive Predictive Value (PPV) 95.4% 93.1-97.1 <0.001* Negative Predictive Value (NPV) 54.7% 43.8-65.1 0.028* Overall Accuracy 89.6% 86.4-92.2 <0.001* The diagnostic performance of the Modified Alvarado Score was assessed by comparing MAS categories with histopathological outcomes. Among the 381 patients with histopathologically proven appendicitis, 352 (true positives) had MAS ≥7, while only 29 patients with appendicitis were missed by MAS (<7), generating a highly significant association (χ² = 276.8, p < 0.001). Conversely, among the 52 patients with a normal appendix, 17 (false positives) had MAS ≥7, whereas 35 (true negatives) had MAS <7, reflecting a reliable discriminative value (95% CI for association: 0.81-0.93). The performance metrics further reinforce this accuracy: MAS demonstrated 92.4% sensitivity, 67.3% specificity, and an excellent 95.4% positive predictive value, all statistically significant. However, the negative predictive value was lower at 54.7%, indicating that lower MAS values do not reliably exclude appendicitis. Figure 1: ROC curve with AUC Table 3: Correlation Between MAS & Histopathology MAS Score Range Patients n (%) Histopathology Positive Histopathology Negative χ² Value p-value ≤4 18 (4.2%) 5 13 χ² = 197.4 <0.001* 5-6 63 (14.5%) 42 21 ≥7 352 (81.3%) 334 18 Total 433 (100%) 381 (88%) 52 (12%) Correlation measure Result Spearman correlation (MAS vs HPE result) ρ = 0.71 strongly positive 95% CI 0.64-0.76 Significance p <0.001* Higher MAS correlates strongly with histopathological confirmation. The distribution of MAS scores across histopathological findings shows a clear positive association between higher MAS values and confirmed appendicitis. Patients with very low scores (≤4) represented only 4.2% of the cohort, of whom the majority (13 of 18) had a normal appendix, confirming the low diagnostic likelihood at this range. Those with intermediate scores (5-6) comprised 14.5% of the sample, with a moderate proportion (42 of 63) testing positive on histopathology. The majority of patients (81.3%) had MAS ≥7, out of which an overwhelming 334 of 352 were histopathologically confirmed, demonstrating the high predictive value of elevated MAS scores. The chi-square analysis (χ² = 197.4, p < 0.001) confirms a strong and statistically significant association between increasing MAS category and true disease status. The correlation analysis further strengthens this finding, with a Spearman’s rho of 0.71 (95% CI: 0.64-0.76), indicating a strong positive correlation between MAS and histopathological confirmation of appendicitis (p < 0.001). Table 4: Negative Appendectomy Rate Analysis MAS Score Category Total Operated Normal Appendix (Negative Appendectomy) Rate % 95% CI p-value MAS ≥7 352 17 4.8% 2.7-7.5 <0.001* MAS <7 81 35 43.2% 32.1-54.9 0.014* Overall Negative Appendectomy Rate 433 52 12% 9.1-15.5 - χ² = 168.3; Interpretation: statistically strong reduction in negative appendectomy when MAS ≥7 MAS threshold ≥7 reduces unnecessary surgeries drastically. The analysis of negative appendectomy rates demonstrates the pivotal role of the Modified Alvarado Score in reducing unnecessary surgeries. Among patients with MAS ≥7 (n = 352), only 17 individuals (4.8%) had a normal appendix, with a narrow confidence interval (2.7-7.5%) and strong significance (p < 0.001), indicating excellent precision and low false-positive rates. In stark contrast, patients with MAS <7 exhibited a markedly higher negative appendectomy rate of 43.2% (35 of 81), with a wider confidence interval (32.1-54.9%) and statistically significant association (p = 0.014). The overall negative appendectomy rate was 12% for the entire cohort. The chi-square value of 168.3 highlights a highly significant reduction in unnecessary appendectomies when MAS ≥7 is used as the decision threshold.

Table 1: Baseline Clinical and Diagnostic Distribution: In the present study of 433 patients, the mean age of those presenting with suspected appendicitis was 29.8 ± 10.6 years, which is consistent with the epidemiological trend reported in several earlier studies. Alvarado et al. (1986)[1] originally noted that acute appendicitis is most prevalent in the second and third decades of life, closely aligning with the present findings. Similarly, Chakraborty et al. (2018)[6] reported a mean age of 27.4 years, supporting the demographic comparability of this cohort. The male predominance (61.4%) observed in this study mirrors the findings of Kalan et al. (1994)[7], who reported a male-to-female ratio of 1.7:1, and Ohle et al. (2011)[4], who found that appendicitis affects males more frequently. The significantly higher mean MAS score of 7.2 ± 1.4, with strong statistical significance (p < 0.001), demonstrates the high preoperative suspicion of appendicitis among this cohort, which is reinforced by the high histopathological confirmation rate of 88%. This correlates with the validation study by Mandeville et al. (2011)[8], which showed histopathology positivity rates between 85% and 90% in surgically treated patients. The negative appendectomy rate (12%) is within the acceptable modern standard of <15%, comparable to the 10-13% rates reported in large multicenter analyses by Flum et al. (2001)[9]. This indicates appropriate clinical judgment and reflects the utility of MAS as a triage tool in surgical decision-making. Table 2: Diagnostic Accuracy of Modified Alvarado Score: The Modified Alvarado Score demonstrated high sensitivity (92.4%), which is in line with the sensitivity range (86%-94%) reported by Al-Hashemy and Seleem (2004) [10], reinforcing MAS as an excellent screening tool. The specificity of 67.3% is comparable to findings by Ohle et al. (2011)[4], who reported MAS specificity of 59-72%. The PPV of 95.4% in this study strongly indicates that MAS ≥7 is highly predictive of true appendicitis, matching the PPV reported by Khan et al. (2016)[8], who found PPV values above 93%. However, the NPV of 54.7% reflects the limitation of MAS in excluding appendicitis when scores are low. This is consistent with prior studies, such as the meta-analysis by Ohle et al. (2011)[4], which highlighted that MAS has lower reliability as a rule-out tool but is highly reliable for rule-in diagnosis. The overall diagnostic accuracy of 89.6% in this study is closely aligned with the accuracy range of 85-90% reported in multiple validation studies, confirming MAS as a robust and dependable clinical scoring system. Table 3: Correlation Between MAS and Histopathology: A strong positive correlation (Spearman’s ρ = 0.71, p < 0.001) was observed between MAS scores and histopathological confirmation, reiterating that higher MAS scores are strongly predictive of true appendicitis. This correlation is in agreement with the findings of Kalan et al. (1994)[7], who demonstrated powerful concordance between increasing clinical score and pathological confirmation. Patients with MAS ≥7 constituted 81.3% of the study cohort, and 94.9% of them had histopathologically confirmed appendicitis, supporting the high diagnostic predictability at this threshold. These findings are consistent with the study by Mandeville et al. (2011)[8], who also noted that MAS ≥7 correlates strongly with true pathology. The significant chi-square value (χ² = 197.4) further validates MAS's reliability and statistical association with definitive diagnosis. Table 4: Negative Appendectomy Rate and MAS Utility: The negative appendectomy rate of 4.8% for MAS ≥7 demonstrates the powerful discriminatory capability of the scoring system. This low rate is comparable to the negative appendectomy rates reported by Khan et al. (2016)[11] and Flum et al. (2001)[9], both documenting rates below 10% when MAS was applied appropriately. Conversely, low MAS scores (<7) resulted in a markedly higher negative appendectomy rate of 43.2%, reinforcing that MAS values below the cut-off lack specificity and should prompt further evaluation, as suggested by Al-Hashemy and Seleem (2004)[10]. The statistically significant association (χ² = 168.3, p < 0.001) confirms that MAS ≥7 drastically reduces unnecessary surgeries, supporting global recommendations promoting MAS as a first-line diagnostic tool, especially in resource-limited settings.

The present prospective study demonstrates that the Modified Alvarado Score (MAS) remains a highly reliable, simple, and cost-effective diagnostic tool for evaluating patients with suspected acute appendicitis. With a sensitivity of 92.4%, specificity of 67.3%, and an overall diagnostic accuracy of 89.6%, MAS showed strong concordance with histopathological confirmation, particularly at the threshold score of ≥7. The significantly low negative appendectomy rate (4.8%) in patients scoring ≥7 underscores its practical utility in reducing unnecessary surgical interventions. The strong positive correlation between increasing MAS scores and definitive histopathological diagnosis further validates MAS as a dependable clinical scoring system. Overall, MAS continues to serve as an invaluable triage tool in emergency settings-especially in resource-limited environments-helping clinicians make informed decisions, optimize patient outcomes, and minimize operative burden. LIMITATIONS OF THE STUDY 1. Single-center design: The study was conducted at a single tertiary care hospital, which may limit the generalizability of results to broader populations with differing demographic or clinical profiles. 2. Exclusion of imaging-based comparison: The study did not incorporate ultrasonography, CT scan, or MRI findings, which could have provided additional diagnostic context and allowed a comparative accuracy analysis. 3. Potential selection bias: Only patients who underwent appendectomy were included; patients managed conservatively or who improved without surgery were not assessed, possibly overestimating diagnostic accuracy. 4. Subjective clinical parameters: Components of MAS such as rebound tenderness and anorexia rely on clinical judgment and patient reporting, which may introduce inter-observer variability. 5. Limited evaluation of atypical presentations: Special populations (pregnant women, elderly, pediatric patients) were excluded or underrepresented, limiting the applicability of findings to these groups. 6. No assessment of time-symptom relationship: Duration and progression of symptoms were not analyzed, although they may significantly influence MAS scoring and diagnostic performance

1. Alvarado A. A practical score for the early diagnosis of acute appendicitis. Ann Emerg Med. 1986;15(5):557-564. 2. Andersson RE. Meta-analysis of the clinical and laboratory diagnosis of appendicitis. Br J Surg. 2004;91(1):28-37. 3. Körner H, Söndenaa K, Söreide JA, Andersen E, Nysted A, Lende TH, et al. Incidence of acute appendicitis in Norway: influence of diagnostic factors. Eur J Surg. 1997;163(1):23-28. 4. 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. 5. Chong CF, Thien A, Mackie AJ, Tin AS, Tripathi S, Ahmad MA, et al. Comparison of RIPASA and Alvarado scores for the diagnosis of acute appendicitis. Singapore Med J. 2011;52(5):340-345. 6. Chakraborty S, Bag S, Ghosh S, Ray S. Evaluation of clinical scoring systems in acute appendicitis. J Clin Diagn Res. 2018;12(3):PC01-PC05. 7. 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. 8. Mandeville K, Pottker T, Bulloch B, Liu J, Yahata S. Using appendicitis scores in a pediatric emergency department. Pediatr Emerg Care. 2011;27(5):452-456. 9. Flum DR, McClure TD, Morris A, Koepsell T. Misdiagnosis of appendicitis and the use of diagnostic imaging. J Am Coll Surg. 2001;193(2):238-245. 10. Al-Hashemy AM, Seleem MI. Appraisal of the modified Alvarado score for acute appendicitis in adults. Saudi Med J. 2004;25(9):1229-1231. 11. Khan I, Rehman AU, Ali N, Shah SA. Diagnostic accuracy of Modified Alvarado Score in the diagnosis of acute appendicitis. J Ayub Med Coll Abbottabad. 2016;28(3):454-457.