How Accurate Is Ultrasound in Diagnosing Appendicitis? 

A published review explores the growing role of bedside lung ultrasound in neonatal intensive care units (NICUs), highlighting its diagnostic capabilities, clinical advantages, and potential to complement traditional chest X-ray imaging.

Acute appendicitis remains one of the most common causes of abdominal emergencies, yet accurately diagnosing the condition can be challenging. Symptoms such as abdominal pain, nausea, and fever often overlap with other gastrointestinal conditions, making timely and reliable imaging an important part of clinical evaluation.

Ultrasound offers several advantages in suspected appendicitis cases, including portability, accessibility, and no ionizing radiation. But how accurately can it identify appendicitis, and when might additional imaging be necessary?

A 2025 retrospective study published in Cureus, titled Assessing the Efficacy of Ultrasound Imaging for Diagnosing Appendicitis in Male Patients: A Retrospective Study, examined ultrasound's diagnostic performance in male patients with suspected appendicitis.

What Did The Study Examine?

Researchers at Altnagelvin Hospital in Londonderry, United Kingdom, conducted a retrospective analysis of patients evaluated for suspected appendicitis between 2015 and 2022.

The study initially identified 237 male patients aged 14 years and older who underwent abdominal and/or appendix ultrasound examinations. After exclusions, the final analysis included 229 patients.

Researchers evaluated ultrasound findings alongside other imaging modalities, including computed tomography (CT), and reviewed surgical and histopathological findings when available.

The study aimed to determine how effectively ultrasound could identify appendicitis, assess its diagnostic sensitivity and specificity, and examine situations where additional imaging might be beneficial.

Key Findings: 81% Sensitivity and 96% Specificity

The study reported encouraging results for ultrasound in evaluating suspected appendicitis.

Two findings stood out:

• 81% sensitivity: Ultrasound identified a substantial proportion of appendicitis cases, although it could still miss some.
• 96% specificity: Ultrasound demonstrated a high ability to correctly identify patients without appendicitis, suggesting that positive findings can provide valuable diagnostic information.

Ultrasound identified appendicitis in about 20.5% of the study population, while other imaging modalities identified it in about 8.7%.

Among the 229 patients included in the analysis, 62 underwent appendectomy, and 43 had pathologically confirmed appendicitis.

These findings support ultrasound's potential as a useful initial imaging tool. However, the researchers also identified an important limitation: a negative ultrasound examination does not necessarily exclude appendicitis.

Why Negative Ultrasound Findings Deserve a Closer Look

One of the study's most clinically relevant observations involved patients whose ultrasound examinations did not directly demonstrate appendicitis.

Among 149 patients without ultrasound visualization of appendicitis or secondary signs, 14 underwent appendectomy. Two of these patients had histopathological confirmation of acute appendicitis despite their negative ultrasound findings.

Additionally, 25 patients had no direct ultrasound visualization of appendicitis but demonstrated secondary or other findings. Of these patients, six underwent appendectomy, and three had pathological evidence of appendicitis.

These observations highlight the importance of evaluating the complete clinical picture rather than relying on ultrasound findings alone.

Secondary sonographic signs, such as surrounding inflammatory changes or free fluid, may raise suspicion even when the appendix cannot be adequately visualized. However, these findings are not independently diagnostic and require interpretation alongside symptoms, laboratory results, and other clinical information.

The study also reinforces the distinction between a confidently normal appendix and an appendix that simply cannot be visualized. Inconclusive imaging should not automatically be interpreted as the absence of disease.

Ultrasound vs. CT: Understanding Their Complementary Roles

Although ultrasound offers important advantages, CT remains a valuable imaging modality when initial findings are inconclusive or additional abdominal pathology is suspected.

The researchers found a statistically significant association between appendicitis detected by other imaging modalities, particularly CT, and associated pathologies.

This suggests that CT may provide additional diagnostic information in patients with complex presentations or suspected coexisting conditions.

The findings support a thoughtful approach to imaging selection, where ultrasound may serve as an initial examination in appropriate patients, followed by further evaluation when clinical suspicion persists.

Importantly, imaging decisions should consider patient age, clinical presentation, local protocols, and the availability of diagnostic expertise. The study's findings are specific to male patients and should not automatically be generalized to all patient populations.

What This Means for Ultrasound Education and Clinical Practice

Beyond diagnostic performance, the study highlights an important consideration for ultrasound education: the value of accurate image acquisition, interpretation, and recognition of examination limitations.

Ultrasound is an operator-dependent imaging modality. Successfully evaluating suspected appendicitis requires familiarity with abdominal anatomy, appropriate scanning techniques, and the ability to recognize both direct and indirect signs of inflammation.

For healthcare professionals, developing these skills involves more than identifying a single abnormal image. It requires understanding how sonographic findings contribute to broader clinical decision-making.

Recognizing when an examination is inconclusive is equally important. Knowing when to recommend additional imaging or clinical reassessment can help support appropriate diagnostic pathways.

While this retrospective study provides useful evidence, its single-center design, male-only population, and limited diagnostic verification mean the reported accuracy estimates should be interpreted with caution. Larger prospective studies would help further clarify ultrasound's diagnostic performance across different patient populations and clinical settings.

Building Abdominal Ultrasound Skills With SonoSim

Research like this reinforces the importance of comprehensive ultrasound education that extends beyond image recognition to include scanning technique, anatomical understanding, and clinical interpretation.

SonoSim supports healthcare professionals and ultrasound learners with its Abdominal Ultrasound Training, which combines expert-led instruction, interactive learning, and virtual scanning of real patient cases.

Through the SonoSim Ultrasound Training Ecosystem, learners can strengthen their understanding of abdominal anatomy, explore normal and pathologic findings, and develop foundational image acquisition and interpretation skills.

Relevant training topics include GI Tract (Anatomy & Physiology) and Intestinal & Biliary (Core Clinical), which support broader gastrointestinal ultrasound education.

By combining structured education with simulation-based scanning opportunities, SonoSim helps prepare learners for supervised bedside training and the practical challenges of clinical ultrasound.

Explore SonoSim's Abdominal Ultrasound Training to learn more.

Khan W, Mallon C, Bahli Z, et al. Assessing the Efficacy of Ultrasound Imaging for Diagnosing Appendicitis in Male Patients: A Retrospective Study. Cureus. 2025;17(6).
Read the full research article
DOI: 10.7759/cureus.86749