The research team, led by pediatric surgeon Mehmet Metin together with Nurcan Çoşkun, Hülya İpek, Gül Doğan, and senior author Çağatay Evrim Afşarlar, analyzed 675 patients younger than 18 years who underwent appendectomy between 2019 and 2024 at a single center. Rather than relying on clinical impressions, the investigators used histopathology — the microscopic examination of the removed appendix — as the reference standard for whether appendicitis was truly present. This design anchors the study’s numbers to biological ground truth, a level of rigor that many imaging studies in this field lack.

The headline finding concerns how often each imaging modality got the diagnosis right. Ultrasonography, the radiation-free first-line test recommended by pediatric guidelines, detected appendicitis with 79.9 percent sensitivity but only 51.1 percent specificity. In practical terms, ultrasound missed roughly one in five confirmed cases of appendicitis, and when it did flag a problem, it was wrong nearly half the time. Computed tomography showed a different profile: 76.8 percent sensitivity paired with a substantially better 71.7 percent specificity, meaning CT was somewhat more likely than ultrasound to correctly rule out appendicitis when the appendix was actually normal.

These figures illuminate a persistent tension in pediatric radiology. Ultrasound is favored first because it involves no ionizing radiation, is widely available, and children tolerate it well. But the appendix is a small, mobile, gas-filled target, and in children with abdominal pain and guarding, ultrasound visualization can be technically difficult. CT, by contrast, images the entire abdomen with high spatial resolution and is less operator-dependent, but it delivers a radiation dose that, in a developing body, carries a small lifetime cancer risk — a concern that has driven decades of effort to reduce pediatric CT use through clinical scoring systems, MRI protocols, and staged imaging pathways.

The study also explored what happens when both modalities are used in the same patient. In a subgroup of 198 children who had undergone both ultrasound and CT, the investigators tested an exploratory

The exploratory combined rule tested in the dual-imaging subgroup deserves careful interpretation. When the investigators treated a positive result on either ultrasound or CT as sufficient to call appendicitis, sensitivity climbed to 89.2 percent and overall accuracy reached 84.8 percent — figures exceeding either modality alone. The cost was specificity, which fell to 67.5 percent, below CT’s standalone performance. This pattern illustrates a fundamental property of diagnostic test combinations: serially interpreting two tests with an either-positive rule amplifies sensitivity because a patient needs only one of two chances to test positive, but it simultaneously compounds false positives. The authors themselves are explicit that this analysis was exploratory and does not establish that combined imaging is superior overall; the subgroup was not randomized, and the decision to obtain both studies may itself have been driven by clinical uncertainty, embedding selection effects into the result.

That caveat connects to one of the study’s most consequential limitations: CT was performed in 333 of the 675 patients, or 49.3 percent of the cohort, yet the timing, sequence, and clinical indications for those scans could not be consistently retrieved from the records. This is more than a bookkeeping gap. Current pediatric guidelines envision CT as a second-line tool reserved for equivocal ultrasound findings, so nearly half of the cohort receiving CT raises the question of how often the scan followed a genuinely indeterminate ultrasound versus how often it was obtained for other reasons — surgeon preference, emergency department throughput, or medicolegal caution. Without patient-level indication data, the study cannot quantify CT overuse or assess whether the scans were appropriate, which is precisely the utilization question its title promises to address. The authors acknowledge this directly, noting that missing indications prevent any assessment of CT appropriateness.

The design also carries a verification bias that the investigators flag candidly. Because every child in the cohort underwent appendectomy, the study includes no children who were imaged, found to be free of appendicitis, and sent home without surgery. Specificity estimates derived only from operated patients are therefore systematically distorted: children with negative imaging who avoided surgery — the very cases in which ultrasound’s rule-out ability matters most — never entered the denominator. This inflates the apparent false-positive rate of ultrasound and complicates direct comparison with studies that include non-operated patients. It is a well-known structural limitation of appendectomy-based cohorts, and it means the reported specificity figures should be read as conditional on the decision to operate rather than as the real-world performance of the tests across all comers.

Beyond the imaging results, the study contributes a detailed picture of the inflammatory markers that accompany appendicitis in children. C-reactive protein, white blood cell count, absolute neutrophil count, and the neutrophil-to-lymphocyte ratio were all significantly associated with both the diagnosis and the severity of appendicitis, with P values below 0.001 across the comparisons. The neutrophil-to-lymphocyte ratio, a cheap and widely available index of systemic inflammation, has attracted growing interest in surgical literature as a potential adjunct to imaging, and its association with severity in this cohort is consistent with that broader literature. These markers cannot replace imaging, but they can help clinicians stratify pretest probability and decide when an equivocal ultrasound warrants further workup.

Another underappreciated finding is the systematic discrepancy in appendiceal diameter. Both ultrasound and CT underestimated the diameter of the appendix relative to the measurements obtained on histopathological examination, quantified through intraclass correlation coefficients. This is plausible on mechanistic grounds: the appendix is a collapsible tubular structure, and imaging captures it under physiological conditions of intraluminal pressure and muscular tone, whereas fixation and processing of the surgical specimen can alter luminal distension and wall thickness. The practical implication is that diameter thresholds used to declare an appendix abnormal on imaging are calibrated against imaging-based norms, not against the pathological specimen, and clinicians should be cautious about dismissing appendicitis solely because a measured diameter falls just below a published cutoff.

The statistical apparatus of the study also merits note. Beyond conventional sensitivity and specificity, the investigators reported Cohen’s kappa and Gwet’s AC1 to quantify categorical agreement between imaging results and histopathology, and used intraclass correlation coefficients for the continuous diameter measurements. Gwet’s AC1 is particularly useful in settings with high prevalence of agreement, where Cohen’s kappa is known to behave paradoxically and can underestimate agreement; including both gives a more robust picture of how well imaging and pathology correspond. Reporting both metrics reflects an increasing trend toward methodological rigor in diagnostic accuracy research.

Placed in context, the findings reinforce the existing guideline architecture rather than overturning it. Ultrasound’s 79.9 percent sensitivity, while imperfect, is consistent with the range reported in pediatric literature, and its role as a first-line test rests on the absence of radiation rather than on diagnostic supremacy. CT’s higher specificity supports its designated niche as the problem-solving modality for equivocal cases. The study’s real contribution is its unvarnished documentation of how imaging is actually used in practice — with CT deployed in nearly half of appendectomy patients and indication records incomplete — and its demonstration that even in a pathology-anchored cohort, the operational details of imaging pathways remain difficult to reconstruct. For institutions seeking to tighten stewardship of pediatric CT, the message is that structured documentation of imaging indications is a prerequisite: without knowing why each scan was ordered, quality improvement efforts cannot distinguish appropriate escalation from reflexive utilization.

The single-center design in Çorum, Türkiye, also shapes generalizability. Ultrasound performance is notoriously operator-dependent, and results from a high-volume pediatric surgery service with experienced sonographers may not transfer to settings with different expertise or equipment availability. Conversely, the cohort’s size — 675 appendectomies over five years, with 571 histopathologically confirmed cases of appendicitis, a positive rate of 84.6 percent — provides statistical weight that smaller single-center series often lack. The high proportion of confirmed appendicitis also reflects the reality that surgical decision-making in children is conservative, with many equivocal cases proceeding to the operating room, which is precisely the clinical behavior the study’s verification-bias caveat illuminates.

For clinicians, the actionable synthesis is straightforward. Ultrasound remains the appropriate starting point, inflammatory markers can sharpen pretest probability, and CT should be deployed selectively when ultrasound leaves the diagnosis genuinely unresolved. The combined either-positive rule, while attractive on paper for its 89.2 percent sensitivity, should not be adopted as a routine strategy without prospective validation, since its specificity penalty would translate into more negative appendectomies — the outcome pediatric surgery works hardest to avoid. What the study ultimately documents is a gap between guideline intent and bedside practice, and it makes the case that closing that gap begins with better data on why, when, and in whom each imaging study is ordered.

Subject of Research: Diagnostic imaging performance and computed tomography utilization in children undergoing appendectomy for suspected appendicitis

Article Title: Computed tomography utilization patterns and diagnostic imaging performance in children undergoing appendectomy for suspected appendicitis: a real-world cohort study

Article References: Metin, M., Çoşkun, N., İpek, H., Doğan, G., & Afşarlar, Ç. E. (2026). Computed tomography utilization patterns and diagnostic imaging performance in children undergoing appendectomy for suspected appendicitis: a real-world cohort study. BMC Medical Imaging. https://doi.org/10.1186/s12880-026-02957-1

Image Credits: AI Generated

DOI: 10.1186/s12880-026-02957-1

Keywords: appendicitis, computed tomography, ultrasonography, pediatric surgery, diagnostic imaging, histopathology, inflammatory markers, C-reactive protein, medical imaging, appendectomy, diagnostic accuracy, verification bias