European Journal of Cardiovascular Medicine

Upper abdominal pain is a frequently encountered clinical symptom with a broad differential diagnosis encompassing gastrointestinal, hepatobiliary, pancreatic, vascular, and sometimes thoracic causes. While ultrasonography (USG) and contrast-enhanced computed tomography (CECT) of the abdomen are commonly employed to investigate such presentations, thoracic sources of pain are often overlooked, particularly when clinical suspicion is low or the presenting symptoms are atypical (1,2).

Anatomically, the diaphragm acts as a shared boundary between the thoracic and abdominal cavities, and pathologies from one region may manifest as referred pain in the other. Lower lobe pneumonia, pleural effusion, pulmonary embolism, or pericardial disease can present predominantly with upper abdominal discomfort, leading to misdiagnosis or diagnostic delays if thoracic imaging is not pursued (3,4).

Moreover, recent studies emphasize the importance of cross-sectional imaging in evaluating overlapping thoracoabdominal conditions, as chest pathologies are increasingly recognized in patients initially suspected of having purely abdominal disease (5).

Conventional imaging approaches focusing solely on the abdomen may miss critical thoracic findings that impact clinical management. Multidetector CT technology now enables comprehensive imaging of both thoracic and abdominal structures with high spatial resolution and relatively short scan times (6).

Incorporating CT thorax in the imaging protocol may enhance diagnostic accuracy and facilitate timely interventions, especially in emergency and acute care settings.

This study aims to assess the diagnostic utility of CT thorax in detecting concurrent thoracic pathologies in patients presenting with upper abdominal pain, using a multimodality imaging approach, and to evaluate its impact on clinical decision-making.

The study included 120 consecutive adult patients (aged 20–70 years) who presented to the emergency or outpatient department with non-traumatic upper abdominal pain of less than 7 days' duration. Patients with a history of trauma, known malignancy, prior abdominal surgery, or hemodynamic instability were excluded from the study.

Clinical Evaluation and Preliminary Imaging:
All patients underwent a thorough clinical examination followed by routine laboratory investigations. Initial imaging included ultrasonography (USG) of the abdomen performed using a high-resolution ultrasound system with a curvilinear transducer (3.5–5 MHz), focusing on hepatobiliary, pancreatic, renal, and gastrointestinal structures.

Cross-sectional Imaging Protocol:
Subsequently, all participants underwent contrast-enhanced CT (CECT) of the abdomen and thorax using a 128-slice multidetector CT scanner. Scanning was performed in the supine position with breath-holding at end-inspiration. A non-ionic iodinated contrast agent (1.5 mL/kg) was administered intravenously at a rate of 3–4 mL/sec, followed by a saline flush. The abdominal phase was acquired at 70–80 seconds, while the thoracic phase was obtained during the arterial phase at 25–30 seconds. Images were reconstructed at 1–2 mm slice thickness for detailed evaluation.

Image Analysis:
All CT images were independently reviewed by two board-certified radiologists with over five years of experience. Discrepancies in interpretation were resolved by consensus. Findings were classified into three categories: (1) isolated abdominal pathology, (2) isolated thoracic pathology, and (3) combined thoracoabdominal pathology. Clinically significant thoracic findings were defined as those requiring immediate or additional intervention or those that altered the primary diagnosis.

Statistical Analysis:
Data were analyzed using SPSS software version 25.0. Descriptive statistics were used to summarize patient demographics and imaging findings. Categorical variables were expressed as frequencies and percentages. Inter-observer agreement for CT findings was assessed using Cohen’s kappa (κ) coefficient. A p-value of <0.05 was considered statistically significant.

A total of 120 patients presenting with upper abdominal pain were included in the study. The study population consisted of 70 males (58.3%) and 50 females (41.7%), with a mean age of 45.6 ± 12.3 years.

Initial ultrasonography revealed abnormal findings in 76 patients (63.3%), while CECT abdomen identified pathologies in 82 patients (68.3%). CT thorax detected additional thoracic abnormalities in 36 patients (30%) that were not evident on clinical evaluation or abdominal imaging alone.

Among these thoracic findings, pleural effusion (n=12; 10%), basal pulmonary consolidation (n=10; 8.3%), pericardial effusion (n=4; 3.3%), and lower lobe pulmonary embolism (n=3; 2.5%) were the most common (Table 1). Notably, 14 patients (11.6%) with either negative or nonspecific abdominal findings were found to have thoracic pathology as the primary cause of pain.

Of the 36 patients with thoracic abnormalities, 21 (17.5%) had clinically significant findings that influenced diagnosis or management, such as changes in therapy, additional investigations, or specialist referral. A breakdown of the diagnostic categories is presented in Table 2.

Inter-observer agreement between the two radiologists reviewing the CT thorax images was high, with a Cohen’s kappa (κ) coefficient of 0.89, indicating excellent agreement.

Table 1: Distribution of Thoracic Findings Detected on CT Thorax (n=36)

Table 2: Diagnostic Categories Based on Combined Imaging Findings (n=120)

As shown in Table 1, pleural and pulmonary abnormalities were the predominant thoracic findings. Table 2 highlights that nearly 30% of patients had thoracic involvement, either isolated or in combination with abdominal disease, underscoring the clinical utility of CT thorax in such cases

The evaluation of upper abdominal pain is often focused on intra-abdominal organs; however, the anatomical and physiological proximity of the thoracic cavity necessitates a broader diagnostic approach. This study demonstrated that a significant proportion of patients presenting with upper abdominal pain had concurrent or isolated thoracic pathologies, with CT thorax contributing substantially to the diagnostic yield.

In our study, 30% of patients had identifiable thoracic abnormalities on CT thorax, with 17.5% being clinically significant and altering the diagnostic impression or management. This supports earlier findings that thoracic imaging can uncover overlooked causes of abdominal pain, including basal pneumonias, pleural effusions, and cardiac pathology (1,2). Studies have documented that up to 20–35% of lower lobe pulmonary diseases may present with referred upper abdominal discomfort due to diaphragmatic irritation (3,4).

The most common thoracic finding in our study was pleural effusion (10%), followed by basal consolidation (8.3%). These findings are consistent with previous reports where basal pneumonia and parapneumonic effusions were among the most frequently missed diagnoses in patients undergoing only abdominal imaging (5,6). This emphasizes the importance of incorporating CT thorax in cases with nonspecific or inconclusive abdominal findings.

Additionally, 11.6% of patients in our cohort had isolated thoracic pathology as the primary cause of pain, which would have been entirely missed if thoracic imaging was not performed. Kariman et al. reported a similar trend where CT thorax changed the diagnosis in approximately 15% of cases initially suspected of having abdominal pathology (7).

CT imaging offers superior spatial resolution and multiplanar capabilities, allowing detailed visualization of both thoracic and abdominal structures. Modern multidetector CT (MDCT) systems have made it feasible to include thoracic imaging in a single contrast-enhanced scan, without significantly increasing radiation exposure or contrast volume (8,9).

Interdisciplinary integration is crucial in the diagnosis of complex cases involving overlapping symptoms. Lower lobe pulmonary embolism, detected in 2.5% of our patients, is a classic example of thoracic pathology mimicking acute abdominal conditions (10). Previous studies have highlighted that pulmonary embolism can manifest with abdominal pain in 6–10% of cases, particularly when emboli affect the diaphragmatic pleura (11).

Furthermore, pericardial effusion and subtle interstitial lung changes, identified in a minority of our cases, underscore the diagnostic limitations of relying solely on clinical assessment and abdominal imaging (12). It has been shown that nearly 25% of patients with pericardial involvement remain asymptomatic or present with vague upper abdominal symptoms (13).

Our study also reinforces the value of multimodality imaging. While ultrasound remains the first-line modality due to accessibility and cost-effectiveness, its limitations in detecting thoracic abnormalities, particularly those obscured by bowel gas or rib shadows, are well-documented (14,15). The complementary role of CT in providing a holistic evaluation of both thoracic and abdominal regions cannot be overstated, particularly in acute care settings.

A key strength of our study was the prospective design and inclusion of consecutive patients, which minimized selection bias. The high inter-observer agreement (κ = 0.89) further validated the reliability of CT thorax in this diagnostic setting. Nonetheless, limitations include the lack of long-term follow-up to assess clinical outcomes and the relatively small sample size, which may restrict generalizability.

The inclusion of CT thorax in the evaluation of patients presenting with upper abdominal pain significantly enhances diagnostic accuracy by identifying concurrent or isolated thoracic pathologies that may be missed on abdominal imaging alone. This multimodality approach aids in timely clinical decision-making and improves patient outcomes, particularly in cases with atypical presentations or inconclusive abdominal findings.

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