How to tell a patient about a diagnostic error

The follow-up exam showed what no one wanted to see: the lesion that appeared on the CT scan three months ago was not described in the report from the previous visit, and the patient returned with more advanced disease. The resident knows she has to tell him. What she does not know is how to begin, what to say about what happened, whether she should apologize and what happens next.

Telling a patient about a diagnostic error is one of the hardest conversations in medicine, and almost no one trains for it before needing it. This guide shows what patients expect to hear, what holds trainees back, how to structure the conversation, what role the apology plays and what institutional communication and resolution programs show. At the end, there is a table with the steps of the conversation and a checklist.

Key points

• Patients want to know about every error that caused harm: what happened, why it happened, how the consequences will be reduced and how to keep it from happening again (Gallagher et al., 2003).
• In a survey of more than a thousand students and residents, 99% agreed that serious errors should be disclosed, but 87% named at least one barrier to doing so (White et al., 2008).
• Only 33% of these students and residents had received training in error disclosure, and 92% wanted to receive it (White et al., 2008).
• Simulation with a standardized patient improved residents' confidence and performance when disclosing errors (Sukalich et al., 2014; Aubin et al., 2022).
• At a US teaching hospital, after a disclosure program with an offer of compensation, the rate of lawsuits fell from 2.13 to 0.75 per 100,000 visits (Kachalia et al., 2010).
• In an experiment, the expression of empathy played an important role in how people reacted to the explanation of an error (Nazione and Pace, 2015).

What a diagnostic error is and why to talk about it

Diagnostic error in a few words

A diagnostic error is a diagnosis that was not made, was made too late or was made wrong, when the available data allowed another path. It can come from a poorly read exam, from a hypothesis closed too early, from a result that never reached the person who ordered it or from an interrupted visit. The guide on diagnostic pause shows how to reduce some of these errors. This text deals with what comes after, when the error has already happened.

Why the patient needs to know

Disclosing errors is recommended by professional organizations and by ethics experts, and it is what patients want (Gallagher et al., 2003). Beyond the ethical duty, there are practical reasons: the patient needs the information to decide about treatment from now on, and trust in the team depends on how the error is handled. Hiding the error usually turns a clinical problem into a relationship problem.

Error and uncertainty are not the same thing

Not every diagnosis that changes is an error. Medicine works with hypotheses, and a condition can evolve in a way that only becomes clear later. Communicating this uncertainty has its own guide: diagnostic uncertainty: strategies for deciding well. When there really was a failure, such as an exam that was not read or a result that was not seen, the conversation is different, and that is what this guide deals with.

When to tell

The sooner the better, as long as there is enough information for an honest conversation. Waiting for the full investigation can take weeks, and in that time the patient may find out about the error from another professional, from an exam or from the medical record itself. A first conversation can acknowledge what is known, explain what will be done now and set a follow-up for when the analysis is complete. This step-by-step approach allows you to be transparent without promising answers that do not yet exist.

For the student, the practical rule is simple: when you notice a possible error, tell the person responsible for the patient right away. You do not need to be sure an error occurred to raise the doubt. Many mistakes are only corrected because someone, sometimes the newest member of the team, asked whether a result had already been seen.

What patients expect to hear

Four questions the patient wants answered

Gallagher and colleagues brought together 52 patients and 46 physicians in 13 focus groups to understand how each side thinks about disclosing errors (Gallagher et al., 2003). Patients wanted to know about all errors that caused harm and sought four kinds of information: what happened, why it happened, how the consequences would be reduced and how repetition would be prevented (Gallagher et al., 2003).

These four questions are a good script. If the conversation ends without an answer to any of them, the patient will probably leave with the feeling that something was hidden.

What physicians do in practice

The physicians in the same study agreed that errors with harm should be disclosed, but they described that they "choose their words carefully" when talking about them (Gallagher et al., 2003). Both sides had unmet emotional needs after an error (Gallagher et al., 2003). The gap between what the patient wants and what the physician says shows up there: the wish to protect the patient, or oneself, can become a vague explanation.

The weight of the apology

A qualitative study with seven physicians from a neonatal unit in France explored the role of the apology in disclosure (Dahan et al., 2017). The physicians described the apology as part of a set that includes explanation, regret, empathy and ways to prevent repetition (Dahan et al., 2017). The apology helped maintain the relationship shaken by the error, take responsibility and take the first steps toward forgiveness (Dahan et al., 2017).

In an experiment on explanations of medical errors, Nazione and Pace tested the effect of apology, empathy, corrective action and compensation on people's anger, attitudes and intentions toward the professional (Nazione e Pace, 2015). The results suggest that empathy plays a large role in positive reactions after an error (Nazione e Pace, 2015).

In practice, this means preparing the conversation around what the patient needs, not around what is most comfortable to say. Explaining what happened in simple words, acknowledging the impact on the patient's life and showing a concrete plan is usually worth more than the most complete technical explanation.

What holds students and residents back

Everyone agrees, few feel prepared

White and colleagues applied a questionnaire to 1,138 students, interns and residents from two American academic centers, with a response rate of 78% (White et al., 2008). Almost all (99%) agreed that serious errors should be disclosed to patients (White et al., 2008). At the same time, 87% pointed to at least one barrier: thinking the patient would not understand (59%), would not want to know (42%) or might sue the physician (33%) (White et al., 2008).

Errors appear early in training

Personal involvement with errors was common already in the fourth year of medical school (78%) and nearly universal among residents (98%) (White et al., 2008). Among residents, 45% reported involvement in a serious error and 34% had already disclosed a serious error to a patient (White et al., 2008). Even so, only 33% of all participants had received any training for this conversation, and 92% said they wanted to receive it (White et al., 2008).

What students want to learn

A survey of American medical schools showed that the topic is already taught, but without a uniform curriculum across schools (Wojcieszak, 2022). The fourth-year students who responded said they wanted to learn what happens after "sorry": how cases are resolved and what the legal, insurance and compensation aspects are (Wojcieszak, 2022). It is a real gap: knowing what to say in the conversation helps little if you do not know what happens after it.

The physician suffers too

Those who make a mistake also need support. The doctors in Gallagher's focus groups reported emotional needs that were not met after an error (Gallagher et al., 2003). The guide on the second victim addresses this side of the story and how to seek help.

How to structure the conversation

Before entering the room

Disclosing an error is not a task to do alone, especially in medical school or early in residency. Talk with your supervising physician or the doctor in charge beforehand, agree on who will lead the conversation and gather the facts already known. Many hospitals have a patient safety unit that guides this step. Choose a private place, with time, and ask the patient whether they want a family member present.

Before entering, check that these points are settled:

• who will lead the conversation and who will be present;
• what is already known about the error and what is still under review;
• what the clinical plan is from now on;
• who the patient wants by their side during the conversation;
• how much time is available, with no expected interruptions.

During the conversation

Start by stating clearly that something did not go as it should have. Avoid technical detours before getting to the point, because the patient notices hesitation and reads it as an attempt to hide something. Then follow the script of the four questions patients want answered (Gallagher et al., 2003): what happened, why it happened, what will be done now and what will be done to prevent it from happening again.

Say what is known and what is still under review. Do not speculate about who is to blame or attribute the error to absent colleagues. Express regret directly, and leave room for silence, anger and questions. The guide to the SPIKES protocol offers useful steps for difficult conversations that also apply here.

Phrases that help and phrases that get in the way

Word choice matters a great deal. Phrases that open the conversation clearly tend to work better than defensive formulas. Some examples that help:

• "I need to talk with you about something that did not go as it should have."
• "The result of the earlier test showed a change that was not seen in time."
• "I am sorry about this. I understand it is hard to hear."
• "Now, here is what we are going to do."
• "We are reviewing how this happened so that it does not happen again."

Phrases such as "these things happen", "there was no way to know" or "it was a freak accident", said before any review, tend to sound like a defense. The patient wants to know what happened and why (Gallagher et al., 2003), and an explanation that plays down the fact closes the conversation too early.

After the conversation

Record in the medical chart what was said, who was present and what was agreed. Schedule a follow-up, because the first conversation rarely answers everything, and the patient will remember questions at home. Report the event through the service's channels: reporting helps prevent the error from happening again with another patient.

Steps of the conversation in a table

Step	What to do	What to avoid
Prepare	Gather the facts, agree with your supervising physician who leads, choose a private place	Going alone and without information
Open	Say right away that something did not go as it should have	Long technical explanations before the point
Explain	What happened and why, with what is known so far	Speculating, blaming colleagues or the system vaguely
Express regret	Express regret and empathy directly	Generic phrases that sound like a formula
Plan	Say what will be done now for the patient	Ending without a next step
Prevent	Say what will be done to avoid a repeat	Promising what is not up to you
Follow up	Record, report and schedule a follow-up	Treating the conversation as a one-off event

Common mistakes when disclosing an error

• Waiting too long. Putting off the conversation until you have all the answers makes the patient find out another way. It is better to tell what is known and say that the review is ongoing.
• Using vague language. Phrases such as "there was a complication" hide more than they explain. Patients want to know what happened (Gallagher et al., 2003). Use simple, direct words.
• Underestimating the patient. Believing the patient will not understand or will not want to know were the barriers most cited by doctors in training (White et al., 2008). Ask the patient how much they want to know, instead of deciding for them.
• Forgetting empathy. A correct technical explanation does not replace acknowledging the suffering. Empathy appeared as a central element in positive reactions after an error (Nazione e Pace, 2015).

How to train before you need to

What curricula already do

A scoping review found 21 studies describing 19 error communication curricula for residents and students (Stroud et al., 2013). Most were a brief, single session combining a lecture or small group discussion with role play (Stroud et al., 2013). Fourteen studies reported self-rated improvement in knowledge, skills and attitudes, and five used structured assessment and showed improvement in skills, but with small or medium samples (Stroud et al., 2013).

Simulation with a standardized patient

In a program with 55 first-year residents, each one disclosed an error to a standardized patient playing a family member, twice, four weeks apart (Sukalich et al., 2014). Between sessions, they reviewed the video of their own encounter and completed a tutorial (Sukalich et al., 2014). Self-efficacy rose from 119.6 to 150.3 points, and external assessors confirmed the improvement (Sukalich et al., 2014).

In a study with 49 pediatrics residents, the group that received training between two simulations of disclosing an adverse event to simulated parents improved performance from 65.08 to 72.36 points, while the control group did not change (Aubin et al., 2022). The HEEAL curriculum, which combines honesty, empathy, education, apology and prevention, used simulation with deliberate practice in short cycles and also included a conversation among colleagues about the error (Falvo et al., 2024).

How to practice during medical school

If your school offers simulation, ask for an error disclosure scenario. If it does not, practice in pairs with a colleague, using a case discussed in a morbidity and mortality session: one plays the doctor, the other plays the patient, and a third observes with the table above. The guide on morbidity and mortality sessions shows how to make the most of these cases.

What happens next: communication and resolution programs

What these programs are

Communication and resolution programs are institutional structures in which the hospital talks with the patient after an adverse event, investigates what happened, explains and, when appropriate, apologizes, takes responsibility and offers compensation (Kachalia et al., 2018). The idea is to replace defensive silence with an organized response.

What the data show

In the University of Michigan health system, after the implementation of a disclosure program with an offer of compensation, the monthly rate of new claims fell from 7.03 to 4.52 per 100 thousand visits, and the rate of lawsuits fell from 2.13 to 0.75 (Kachalia et al., 2010). Time to resolution fell from 1.36 to 0.95 year (Kachalia et al., 2010). The authors warn that the study design does not allow claiming causality (Kachalia et al., 2010).

In four Massachusetts hospitals, the implementation of these programs was associated with better trends in some indicators, and no hospital had worsening in liability indicators (Kachalia et al., 2018). A 2025 rapid review found nine primary studies and concluded, with low-strength evidence, that the more solid programs reduced the rate of claims and defense costs (Sokol-Hessner et al., 2026). Data on the effects for patients, families and professionals are lacking (Sokol-Hessner et al., 2026).

The patients' experience

Interviews with 27 patients, 3 family members and 10 professionals from three American hospitals with these programs explored what helped and what got in the way of reconciliation after a harm (Moore et al., 2017). The study shows that how the institution responds matters to the patient as much as the financial outcome. For you, in training, the lesson is simple: the conversation you have on the first day is part of that process.

Diagnostic reasoning with NEXO

Some diagnostic errors come from hypotheses closed too early. Training reasoning on short cases helps you notice when you are clinging to a hypothesis. NEXO offers one clinical case a day, fictional, with a real clinical presentation, solved in up to six clues, with feedback by proximity in ICD-10. Getting it wrong there has no consequence for anyone, and the feedback shows how far each guess was from the answer. To understand the whole game, see what NEXO is.

If you coordinate a residency program or a patient safety course and want cases to discuss, meet NEXO Closer. Researchers in medical education can propose studies through NEXO Researcher, physicians who review cases take part through NEXO Curator and those who create health content on social media can take part through NEXO Creators.

Frequently asked questions

Should a student disclose an error to the patient?

Not alone. The student should tell the preceptor or the physician in charge, who leads the conversation. Taking part as an observer, with permission, is a good way to learn.

Does apologizing mean admitting fault?

Expressing regret is different from assigning fault before the investigation. Physicians interviewed described the apology as a way to keep the relationship and take responsibility (Dahan et al., 2017). Follow your service's guidance on how to do it.

Does disclosing the error increase the risk of a lawsuit?

The available data do not show that. In an American teaching hospital, the lawsuit rate fell after a disclosure program (Kachalia et al., 2010), and in four Massachusetts hospitals none had worse indicators (Kachalia et al., 2018). The studies are observational and do not prove cause.

What if the patient gets angry?

Anger is an expected reaction. Listen without defending yourself, acknowledge the feeling and keep offering follow-up. Empathy weighs on reactions after an error (Nazione and Pace, 2015).

How can I train without having been through this?

Simulation with a standardized patient improved residents' confidence and performance (Sukalich et al., 2014; Aubin et al., 2022). Role-play in small groups is also used in most curricula (Stroud et al., 2013).

What should I do with my own guilt?

Talk to someone you trust, such as the preceptor, a colleague or the institution's support service. Physicians also have emotional needs after an error (Gallagher et al., 2003).

Checklist for disclosing a diagnostic error

• I told the preceptor or the physician in charge.
• I gathered the facts already known.
• I agreed on who will lead the conversation.
• I chose a private place and set aside time.
• I opened by saying that something did not go as it should have.
• I explained what happened, why, what will be done and how to avoid a repeat.
• I expressed regret and left room for questions.
• I recorded the conversation, reported the event and scheduled a follow-up.

Want to train reasoning where getting it wrong costs nothing? Play the case of the day on NEXO.

References

1. Gallagher TH, Waterman AD, Ebers AG, et al. Patients' and physicians' attitudes regarding the disclosure of medical errors. JAMA. 2003. https://pubmed.ncbi.nlm.nih.gov/12597752/
2. White AA, Gallagher TH, Krauss MJ, et al. The attitudes and experiences of trainees regarding disclosing medical errors to patients. Acad Med. 2008. https://pubmed.ncbi.nlm.nih.gov/18316869/
3. Kachalia A, Kaufman SR, Boothman R, et al. Liability claims and costs before and after implementation of a medical error disclosure program. Ann Intern Med. 2010. https://pubmed.ncbi.nlm.nih.gov/20713789/
4. Kachalia A, Sands K, Niel MV, et al. Effects Of A Communication-And-Resolution Program On Hospitals' Malpractice Claims And Costs. Health Aff (Millwood). 2018. https://pubmed.ncbi.nlm.nih.gov/30395501/
5. Sokol-Hessner L, Stewart CM, Sharma R, et al. Programs for responding after patients are harmed by their healthcare: A Making Healthcare Safer IV rapid review. J Patient Saf Risk Manag. 2026. https://pubmed.ncbi.nlm.nih.gov/42369169/
6. Stroud L, Wong BM, Hollenberg E, et al. Teaching medical error disclosure to physicians-in-training: a scoping review. Acad Med. 2013. https://pubmed.ncbi.nlm.nih.gov/23619064/
7. Sukalich S, Elliott JO, Ruffner G. Teaching medical error disclosure to residents using patient-centered simulation training. Acad Med. 2014. https://pubmed.ncbi.nlm.nih.gov/24280843/
8. Wojcieszak D. Measuring the Uptake of Disclosure and Apology Content in the American Medical School Curriculum. J Med Educ Curric Dev. 2022. https://pubmed.ncbi.nlm.nih.gov/35399788/
9. Dahan S, Ducard D, Caeymaex L. Apology in cases of medical error disclosure: Thoughts based on a preliminary study. PLoS One. 2017. https://pubmed.ncbi.nlm.nih.gov/28759586/
10. Nazione S, Pace K. An Experimental Study of Medical Error Explanations: Do Apology, Empathy, Corrective Action, and Compensation Alter Intentions and Attitudes? J Health Commun. 2015. https://pubmed.ncbi.nlm.nih.gov/26134489/
11. Moore J, Bismark M, Mello MM. Patients' Experiences With Communication-and-Resolution Programs After Medical Injury. JAMA Intern Med. 2017. https://pubmed.ncbi.nlm.nih.gov/29052704/
12. Falvo L, Bona A, Heniff M, et al. How to HEEAL: A Patient and Peer-Centric Simulation Curriculum for Medical Error Disclosure. MedEdPORTAL. 2024. https://pubmed.ncbi.nlm.nih.gov/38567116/
13. Aubin J, Rivolet O, Taunay AL, et al. Benefit of Simulation-Based Training in Medical Adverse Events Disclosure in Pediatrics. Pediatr Emerg Care. 2022. https://pubmed.ncbi.nlm.nih.gov/34398860/