Diagnostic Errors

The spectrum of diagnosis-related claims spans a broad range of clinical outcomes in which it is alleged that the correct diagnosis for a patient has not been made in a timely manner. Incidents arising are often process-related, occurring during the pre- and post-analytic phases when specimens are collected or images taken and results are reported. In spite of historical improvements in patient outcomes, liability claims still arise from diagnostic error (missed, wrong, or delayed diagnosis) and failure to communicate results or refer patients to the next point of clinical intervention.

Expected Outcomes

Adopt a standardized evidence-based CTR protocol.

Complete and timely documentation of decisions and actions taken in response to shared decision making (informed choice-informed consent) and CTRs.

Adopt a standardized, interdisciplinary, collaborative, and evidence-based protocol for conducting quality of care reviews involving diagnostic errors resulting in patient harm or death; incorporate system thinking and human factors concepts into the review process. 

Definitions and Acronyms

  • CTAS – Canadian triage and acuity scale
  • CTR – critical test results
  • Lookback review – process that involves the identification, tracing, notification/disclosure and ongoing care/monitoring of a select group of patients potentially impacted by a safety event, alert, recall, or advisory
  • Medical directive – written orders from healthcare providers for the performance of treatments, interventions or procedures on particular patients when specific conditions and circumstances are met; the orders delegate controlled acts from regulated health professionals with the authority to perform them to regulated / unregulated health professionals who are not independently authorized to perform them
  • MRP – most responsible practitioner, often a nurse practitioner, midwife or physician
  • Ordering practitioners – include MRPs and other healthcare providers ordering / performing test through delegation (e.g., medical directive)
  • Pre-analytic phase – involves selecting the appropriate test, obtaining the specimen, labeling it with the patient's name, providing timely transport to the laboratory, registering receipt in the laboratory, and processing before testing
  • Post-analytic phase – involves result reporting, interpretation, and distribution
  • SOP – standard operating procedure

Common Claims Themes and Contributing Factors

  • Cumbersome and / or ineffective discrepant CTR protocols and practice. 
  • Unclear accountabilities and / or inadequate processes related to the:
    • Review and communication of abnormal or critical results to the MRP;
    • Follow-up on outstanding, delayed, and missing test results (e.g., MRP not following up on results as assumed the hospital or patient would call if results not received);
    • Follow-up on test results ordered, including (but not limited to) results received post discharge and/or in the non-hospital setting;
    • Patient call-back (e.g., who is to call the patient and under what circumstances; actions to be taken when patient is not responding).
  • Inconsistent processes to ensure timely (24 / 7 / 365) and complete access to clinical records of prior attendances.
Office and Clinic-Based Care Settings
  • Inadequate diagnostic test management process.
  • Inappropriate use of administrative staff and students to screen test results.
  • Failure to acknowledge or act on concerns raised by the patient / client or family.
Knowledge and Judgment
  • Lack of team and MRP awareness and / or lack of compliance with local or regional CTR protocol and policies. 
  • CTR results communicated to unregulated staff and unit clerks versus the ordering practitioner or designate.
  • Misinterpretation of imaging results leading to missed and delayed diagnosis.
  • Inadequate histories and exams. 
  • Tests not performed or delayed testing due to:
    • Requisitions not completed properly;
    • Improper specimen collection, labelling, and / or transport;
    • Lack of awareness and / or compliance with related medical directives.
  • No audit trail (documentation) to support the receipt and communication of CTR results.
  • Inconsistent documentation of shared decision making (informed choice – informed consent) surrounding routine and recommended diagnostic testing.

Mitigation Strategies

Care Processes

  • Adopt a standardized evidence-based CTR protocol (Hanna, Griswold, Leape, & Bates, 2005) (College of Physicians and Surgeons of Ontario, 2019) (Keogan, Mannion, & McCormack, 2021).

Additional Considerations

Examples of elements to address in CTR and discrepant test results protocols:
  • Clear definitions of key terms (e.g., what is deemed ‘critical’ versus ‘significantly abnormal’);
  • Who should receive the results;
  • Who should receive the results when the ordering practitioner is not available;
  • A standardized escalation process with clearly defined steps for CTR communication and time thresholds for next steps if the appropriate professional cannot be reached;
  • Communication and management of CTR in ambulatory and community clinics, after patient discharge, after-hours, weekends, and holidays;
  • A chain of responsibility and explicit time frames for communication of CTR for all patients in all care settings overseen by the healthcare organization;
  • How the communication is to take place (e.g., laboratory and diagnostic imaging staff are to state the emergency nature or level of urgency of the call, provide the name of the patient and the test, and test results);
  • The need to communicate CTR and discrepant test results verbally in addition to electronic notifications;
  • A carefully defined, limited list of CTRs requiring reporting directly to the MRP (e.g., reports of malignant or possibly malignant tissue; significant variance between frozen section and final reports; amended reports based on special stains or testing; new or substantively changed diagnoses by an outside consultant; recommendations for follow up or repeat tests such as when test results do not correlate with the clinical presentation).
  • Adopt a standardized process / system for the safe and effective management of diagnostic tests to ensure outstanding, abnormal, and CTR are received in a timely manner and acted upon as necessary, including pending test results post discharge or transfer to another practitioner, program, or facility.
  • Implement formal best practice strategies to improve diagnostic safety, quality, and accuracy (The Leapfrog Group, 2022).    
  • Adopt an evidence-based and standardized pathology specimen collection and preparation protocol to facilitate the reliable collection, labeling, and transport  of specimens (Laboratory Physicians in Ontario, 2022) (Lott, et al., 2022).
  • Implement a validated, evidence-based, SOP for pathology specimen processing.
  • Implement a standardized process:
    • For prospective consultations related to second readings and confirmation of all new diagnoses that may lead to significant clinical interventions or new malignancies;
    • To facilitate reliable pre-operative review of all diagnostic tests, including (but not limited to) biopsy results and addendum reports prior to surgery.
  • Establish formal linkages with academic health science partners with respect to consultation for confirmation of specialized (e.g., low volume, high complexity) areas of pathology.
  • Implement formal strategies to facilitate routine, interdisciplinary pathology rounds with pathology and relevant hospital departments (e.g., surgery, oncology).

Strategies for Office and Clinic-Based Care Settings 

  • Adopt standardized best office / administrative practices for:
    • Patients who are expected by the clinic but do not arrive and / or are not available for home visits;
    • Cancelling and re-scheduling appointments in consideration for the social context of patients who may need additional flexibility;
    • Relaying calls / inquires from patients / families to the MRP;
    • Ensuring the laboratory and diagnostic service in the community and hospital have access to current contact information for the MRP or the office / clinic.

Additional Considerations

Examples of elements to consider in the office / clinic-based practice setting related to diagnostic tests:
  • Clarifying accountabilities for the ordering MRP, other practitioners (back-up / second team), students, and clinic administrative staff;
  • Prohibiting the practice of filing test results in the chart with the expectation the ordering MRP will review them the next time the patient / client is seen;
  • Adopting a formal process to ensure a MRP acknowledges test results prior to filing, including results with normal findings or results initially reviewed by students and support staff;
  • Recording or validating the date and time the results are received, reviewed, and discussed with the patient / client; 
  • Ensuring all patient / client handoffs include a review of critical results and discussion of pending tests;
  • Ensuring personal contact with the patient / client for call-back notifications. Do not rely on voice mail, email, or text for delivering the message.

Health Equity

  • Implement a formal strategy to ensure all diagnosis related clinical policies, procedures, guidelines, algorithms, and practices are reviewed from an anti-racist and DEIB perspective (e.g., are the policies / protocols and practices culturally safe and free of biases and stereotypes based on race, religion, ability, gender identity, or sexual orientation) (Vyas, Eisenstein, & Jones, 2020) (Kane, Bervell, Zhang, & Tsai, 2022) (Becker, 2021) (Cerdena, Plaisime, & Tsai, 2020) (Neal & Morse, 2021) (Ibrahim & Pronovost, 2021).


  • Adopt a standardized format for communicating pathology results using uniform, cancer-specific grading systems and terminology (Varma, et al., 2023).
  • Implement formal strategies to improve and enhance the documentation of CTR results delivery and receipt including (but not limited to):
    • Upon delivery and receipt of test results;
    • When communicating with the ordering MRP or designate (Hanna, Griswold, Leape, & Bates, 2005) (The Joint Commission, 2019).
  • Implement strategies to ensure internal, external, and regional laboratory, diagnostic imaging, cardiology, and radiology programs:
    • Have access to up-to-date MRP contact information;
    • Are oriented to the organization’s and / or program’s CTR protocol and process.

Strategies for Ordering Practitioners

  • Adopt formal and standardized follow-up protocol / practices for ordered tests to ensure outstanding and abnormal test results are received in a timely manner and acted upon as necessary, including pending test results post discharge or transfer to another practitioner, program, or facility (College of Physicians and Surgeons of Ontario, 2019) (Canadian Medical Protective Assoication, 2021) (Canadian Medical Protective Association, 2020) (British Columbia College of Nurses & Midwives, n.d.).
  • Adopt strategies to minimize diagnostic errors (e.g., considering differential diagnosis; obtaining enough information to formulate a diagnosis; revisiting the diagnosis if symptoms persist; avoiding workarounds and inappropriate deviations from standard practice; awareness of cognitive biases).

Procurement and Contract Management

  • Where utilized, incorporate the organization’s and / or programs’ CTR expectations into contracts and agreements with external or third party service providers (e.g., laboratory, diagnostic imaging, cardiology, and radiology service providers).

Team Training and Education 

  • Implement formal strategies to support and enhance the team’s knowledge, skills (technical and non-technical), and practical experience surrounding CTR and diagnostic errors; ensure the team training and education strategies consider or involve all teams members (cross-departmental and disciplines) involved in the CTR and diagnostic process. 


Strategies for MRPs and Ordering Practitioners

  • Avoid leaving fields and checkboxes unanswered in paper-based and electronic records; record the rationale for interventions and tests not performed.
  • Provide clinically significant prompts on requisitions, referrals, and screening forms to assist radiologists and other specialists.
  • Avoid:
    • Ambiguous and / or inadequate assessment findings and referral notes;
    • Using “dictated but not read” disclaimer on transcriptions (does not decrease liability).
  • Implement strategies to facilitate complete and timely documentation of concerns or complaints expressed by the patient remotely (phone, text, email, etc.), including:
    • Date and time the concerns or complaints were relayed;
    • Details of the concern or complaint and level of urgency;
    • Specific advice or instructions provided to the patient / client or family member;
    • Date and time concerns or complaints were resolved.
  • Implement strategies to facilitate complete and timely documentation:
    • Surrounding all offers and / or recommendations for diagnostic and laboratory testing and outcomes of shared decision making (informed choice-informed consent);
    • Of the risks discussed and associated with declining attendance at clinic / hospital, recommended testing and / or specialist consultation;
    • Of the rationale for not offering or ordering a test to rule out a potentially serious diagnosis (documenting “patient testing declined” is insufficient).

Incident / Emergency Response 

  • Adopt a standardized best practice multi-patient lookback review process (HIROC, 2018) (HIROC, 2015) (Incident Analysis Collaborating Parties, 2012).

Monitoring and Measurement

  • Adopt a standardized, interdisciplinary, collaborative, and evidence-based protocol for conducting quality of care reviews involving diagnostic errors resulting in patient harm or death (Machen, 2023); incorporate system thinking and human factors concepts into the review process (Incident Analysis Collaborating Parties, 2012). 
  • Implement an evidence-based peer review program to monitor and measure the quality of pathology and radiology diagnostic performance, including collaborative peer reviews with other healthcare organizations if the organization lacks a critical mass of radiologists or interpreting physicians (Health Quality Ontario, 2014).
  • Adopt standardized quality indicators for:
    • Point of care testing;
    • CTR and discrepant test notification;
    • Laboratory services;
    • Pathology services;
    • Diagnostic performance with a focus on conditions that are relatively common to be missed which can lead to patient harm.

Additional Considerations

Examples of best practice for peer reviews:
  • Standardized rules and procedures governing the reviews;
  • Actions to be taken on significantly discrepant peer review findings;
  • Strategies for remediation and re-education at the practitioner and department levels;
  • Just culture;
  • Use of recognized Canadian and North American peer review guidelines; 
  • Use of day-to-day and randomly selected cases versus only ‘exceptional’ cases; 
  • De-identifying cases as to patient and practitioner where possible;
  • Focus on generalized learning applicable to future similar patients and evaluating organization, workplace and environmental hazards in conjunction with practice issues (such as knowledge, competency and behaviour).
  • Incorporate learning from local, provincial, and national diagnostic patient harm incidents and data into local protocols as well as staff and patient education and training (Grenon, Szymonifka, Alder-Milstein, Ross, & Sarkar, 2023) (Schaffer, 2019). 

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