The research team set out to answer a deceptively simple question: once a clinician knows a child’s age, Pediatric Appendicitis Score, and C-reactive protein level, how much additional diagnostic value does an appendicitis-compatible initial ultrasound report actually provide? This question matters because ultrasound is widely used as the first-line imaging modality in children with suspected appendicitis, particularly given concerns about radiation exposure from computed tomography in young patients. Yet the incremental value of the initial ultrasound report, considered alongside established clinical variables, has remained surprisingly unclear in the literature. Prior studies have integrated ultrasound findings with clinical scores, refined sonographic criteria using age-based appendiceal measurements and secondary signs, and explored the meaning of partial appendix visualization, but few prospective cohorts have directly measured the statistical gain that ultrasound adds to a baseline clinical model.

To address this gap, the investigators conducted a prospective single-centre cohort study enrolling children aged 3 to 17 years who were evaluated for suspected acute appendicitis between May 2025 and March 2026. The primary outcome was histopathologically confirmed appendicitis, a rigorous standard that anchors the diagnostic analysis in tissue-level truth rather than clinical impression alone. The study design compared two statistical models. The first, a clinical model, included age, the total Pediatric Appendicitis Score, and log2-transformed C-reactive protein values. The second, an ultrasound-extended model, added an appendicitis-compatible initial ultrasound report to those same variables. Model performance was assessed using the area under the receiver operating characteristic curve, known as the AUC, along with the Brier score, likelihood-ratio testing, and the DeLong method for comparing correlated receiver operating characteristic curves.

The cohort comprised 135 children evaluated through an ultrasound-first pathway. Of these, 81 had histopathologically confirmed appendicitis, while 54 formed the comparison group of children in whom appendicitis was ultimately excluded. The clinical model alone demonstrated moderate apparent discrimination, achieving an AUC of 0.771 with a 95 percent confidence interval spanning 0.689 to 0.852, and a Brier score of 0.188. These figures describe a model that performs meaningfully above chance but still leaves substantial diagnostic uncertainty in individual cases, a familiar reality for clinicians who know that scores and inflammatory markers can overlap considerably between children who need surgery and those who do not.

The headline result emerged when ultrasound entered the equation. Among the 132 children whose initial ultrasound reports could be classified, the addition of an appendicitis-compatible ultrasound report increased the AUC from 0.772 to 0.912 and reduced the Brier score from 0.187 to 0.113. In practical terms, the AUC jump represents a substantial improvement in the model’s ability to separate children with confirmed appendicitis from those without it, moving discrimination from the moderate range toward levels typically associated with highly reliable diagnostic tools. The Brier score, which measures the mean squared difference between predicted probabilities and actual outcomes, fell by nearly 40 percent, indicating that the ultrasound-extended model produced not only better ranking of patients but also better-calibrated probability estimates. The likelihood-ratio framework confirmed that the improvement was statistically meaningful rather than a product of chance variation within the sample.

These numbers carry weight for anyone who has followed the evolution of pediatric appendicitis diagnostics. The Pediatric Appendicitis Score, originally described by Samuel in 2002, combines clinical findings such as migration of pain, anorexia, fever, and rebound tenderness into a structured assessment. C-reactive protein, an acute-phase reactant measurable within hours, has been validated through systematic reviews and meta-analyses as a useful but imperfect marker of inflammation in pediatric appendicitis. Previous work by Bachur and colleagues in 2015 demonstrated the value of integrating ultrasound findings with clinical scores, and subsequent studies have refined sonographic criteria by combining age-based appendiceal size thresholds with secondary findings such as periappendiceal fluid and echogenic fat. The new study extends this lineage by prospectively quantifying, within a single cohort, the exact statistical increment that a clear ultrasound report delivers on top of those established variables.

The study also examined the role of post-ultrasound computed tomography within the same ultrasound-first pathway. CT was performed in 52 of the 135 children, representing 38.5 percent of the cohort. Among those children, 29 had appendicitis, while 23 did not undergo appendectomy. This figure illustrates a persistent tension in pediatric imaging strategy: ultrasound is favored as the initial modality because it avoids ionizing radiation, but equivocal or negative ultrasound findings in children with persistent clinical suspicion often prompt a second-line CT examination. The ACR Appropriateness Criteria for suspected appendicitis in children endorse this staged approach, and prior implementation studies have shown that ultrasound and fast magnetic resonance imaging pathways can reduce CT utilization. The new data suggest that when the initial ultrasound report is clearly appendicitis-compatible, its diagnostic contribution is strong enough to anchor clinical decisions, while the residual group with inconclusive imaging continues to require careful escalation.

Methodologically, the choice of log2-transformed C-reactive protein reflects the skewed distribution typical of inflammatory markers, where a small number of children with very high values would otherwise dominate a linear model. The use of the DeLong comparison, a standard method for testing whether two correlated AUCs differ significantly, strengthens the inference that the ultrasound-extended model genuinely outperforms the clinical baseline rather than merely appearing to do so in this particular sample. The Brier score decomposition further distinguishes discrimination from calibration, two properties of a predictive model that can diverge: a model may rank patients correctly yet assign probabilities that are systematically too high or too low. The observed reduction from 0.187 to 0.113 indicates improvement on both fronts, which is precisely what clinicians need when translating a statistical model into bedside decisions about observation, imaging escalation, or surgical consultation.

The authors frame their conclusion carefully: a clear appendicitis-compatible initial ultrasound report provided substantial incremental diagnostic information when added to age, Pediatric Appendicitis Score, and C-reactive protein, supporting the role of ultrasound as an integrated component of the diagnostic assessment rather than a standalone test. This framing resists the common temptation to treat any single test as definitive. Appendicitis in children remains a condition in which history, physical examination, laboratory data, and imaging each contribute partial information, and the art of diagnosis lies in combining them coherently. The study’s prospective design, histopathological gold standard, and formal statistical comparison give its central claim unusual solidity for a single-centre cohort.

The implications reach beyond the radiology suite. For emergency physicians and pediatric surgeons, the results support protocols in which ultrasound findings are interpreted in the context of validated scores and inflammatory markers, rather than in isolation. For health systems weighing imaging investments, the data quantify the value of maintaining high-quality pediatric ultrasound services as the backbone of an ultrasound-first pathway. And for researchers, the study provides a template for measuring incremental diagnostic value with the rigor that the field increasingly demands. As pediatric appendicitis diagnostics continue to evolve, with standardized reporting templates, refined sonographic criteria, and alternative second-line modalities all under active investigation, this prospective cohort from Kütahya offers a clear quantitative answer to a question that clinicians have long asked in qualitative terms: ultrasound matters, and now the size of its contribution can be stated with confidence.

Subject of Research: Diagnostic value of ultrasound in pediatric suspected acute appendicitis

Article Title: Incremental diagnostic value of ultrasound in children with suspected acute appendicitis

Article References: Ibrahimoglu, H., & Sahin, S. (2026). Incremental diagnostic value of ultrasound in children with suspected acute appendicitis. Pediatric Radiology. https://doi.org/10.1007/s00247-026-06812-x

Image Credits: AI Generated

DOI: 10.1007/s00247-026-06812-x

Keywords: acute appendicitis, ultrasound, pediatrics, Pediatric Appendicitis Score, C-reactive protein, diagnostic accuracy, computed tomography, pediatric radiology, AUC, emergency medicine, histopathology, ultrasound-first pathway