A triple threat to diagnostic safety in CTPA: Diagnostic uncertainty, sspe, and reporting discrepancies

Abstract Background: CT pulmonary angiography (CTPA) is the gold standard for diagnosing pulmonary embolism (PE), yet inconsistencies in reporting may compromise diagnostic accuracy and patient safety. At our institution, CTPA reports are unstructured narrative text, and informal observations raised concern about diagnostic uncertainty, possible overdiagnosis of small subsegmental PE (SSPE), and internal inconsistencies within reports. We conducted this structured quality review to evaluate the prevalence and nature of these three diagnostic vulnerabilities: uncertainty in diagnosis, identification of SSPE, and reporting discrepancies. Methods: We conducted a retrospective quality review of all quantitative CTPA studies performed at our institution between February and June 2025. Each report was assessed to determine PE presence, chronicity (acute, chronic, acute on chronic), and anatomical location (subsegmental vs. more proximal). Two independent hematologists reviewed all reports, with discrepancies resolved by consensus. The goal was to quantify the frequency and characteristics of three diagnostic vulnerabilities: diagnostic uncertainty, SSPE, and reporting inconsistencies. Diagnostic uncertainty was defined as any report where the radiologist explicitly stated that segmental or more proximal PE could not be excluded, without a definitive conclusion. Reporting discrepancy was defined as discordance within a single report between the body and the impression in any of the following: (1) presence or absence of PE, (2) chronicity classification (acute vs. chronic), (3) anatomical location (SSPE vs. more proximal). The study was approved by the Institutional Review Board, and informed consent was waived Results: A total of 1,800 CTPA studies were reviewed. Of these, 226 (12.6%) were positive for PE and 1,537 (85.4%) were negative. Among positive cases, 162 (71.7%) were acute, 50 (22.1%) chronic, and 14 (6.2%) acute on chronic. Diagnostic Uncertainty: Uncertainty was identified in 37 studies (2.1%) where radiologists explicitly stated inability to exclude segmental or more proximal PE. Small Subsegmental PE (SSPE): SSPE was reported in 38 cases (16.8% of PE-positive). Of these, 34 patients (89.5%) were anticoagulated, 9 (23.7%) were admitted, and 1 (2.6%) experienced a bleeding event. Reporting Discrepancies: Seven reports (3.1%) exhibited internal inconsistencies between the body and impression: 3 related to chronicity, 2 to anatomical location, and 2 to presence or absence of PE. Conclusion: Our findings reveal a triple threat to diagnostic safety in CTPA: diagnostic uncertainty, SSPE, and reporting discrepancies. Diagnostic uncertainty poses risks of both delayed and missed diagnoses. We observed a higher-than-reported rate of SSPE, which may signal potential overdiagnosis, with consequences including unnecessary anticoagulation, bleeding complications, and avoidable hospital admissions. Internal discrepancies within reports may lead to inappropriate management and erode clinician trust. These findings underscore the need for structured reporting, standardized diagnostic terminology, and multidisciplinary oversight to enhance reliability and safeguard patient outcomes.