A nursing diagnosis is a structured statement that captures your clinical judgment about a patient’s response to a health condition or life situation. Unlike a medical diagnosis, which names a disease, a nursing diagnosis identifies the human response to that disease and guides the care you can independently provide. Writing one correctly means combining a specific problem label with its cause and the evidence you observed, following a standardized format.
How Nursing Diagnoses Differ From Medical Diagnoses
A medical diagnosis identifies a disease or pathology: pneumonia, diabetes, fractured femur. A nursing diagnosis identifies how that condition affects the patient’s daily functioning, comfort, safety, or ability to cope. A patient with pneumonia might have the medical diagnosis handled by a physician, but the nursing diagnosis addresses problems like ineffective airway clearance, activity intolerance, or anxiety about breathing. Both types of diagnosis use a systematic reasoning process and aim toward specific outcomes, but they operate in different lanes. A medical diagnosis alone does not provide enough information to plan nursing care, which is why the two work together to give a fuller picture of the patient’s actual situation.
The Three Types You Need to Know
Each type of nursing diagnosis has a slightly different structure, so knowing which one you’re writing determines how you’ll format the statement.
Problem-Focused Diagnosis
This is the most common type. It describes a health problem that currently exists and that you can support with observable evidence. A problem-focused diagnosis has three components: the diagnostic label (the problem), related factors (the cause), and defining characteristics (the signs and symptoms you actually observed or the patient reported). For example: “Ineffective breathing pattern related to decreased lung expansion as evidenced by dyspnea, coughing, and difficulty breathing.” Every piece of that statement is anchored to something you assessed.
Risk Diagnosis
A risk diagnosis identifies a problem that hasn’t happened yet but is likely to develop based on the patient’s specific vulnerabilities. Because the problem isn’t present yet, you won’t have signs and symptoms to cite. The statement uses “risk for” as a prefix and then lists the risk factors instead of defining characteristics. For example: “Risk for falls related to history of falls, impaired mobility, and use of sedative medications.” Your clinical judgment here is predictive, flagging a danger so the care plan can prevent it.
Health Promotion Diagnosis
This type applies when a patient is already functioning well in some area but expresses motivation to improve. It focuses on wellness and quality of life rather than illness. The structure is simpler because there’s no “problem” in the traditional sense. An example: “Readiness for regular exercise related to expressed interest in starting a fitness program.” You’ll use this less often in acute care settings, but it’s essential in community health and outpatient contexts.
The PES Format Step by Step
The PES format is the standard framework for writing a problem-focused nursing diagnosis. PES stands for Problem, Etiology, and Signs/Symptoms. Mastering this format is the core skill.
P (Problem): This is the diagnostic label, a concise name for the patient’s health response. It usually has two parts: a qualifier (a word like “impaired,” “ineffective,” “deficient,” or “risk for” that modifies the meaning) and a focus (the specific function or need affected, like “tissue integrity” or “gas exchange”). The label comes from NANDA-I’s standardized list of approved diagnoses, not from your own phrasing. Using the exact approved terminology ensures that other nurses, documentation systems, and care plans all speak the same language.
E (Etiology): This is the cause or contributing factor, connected to the problem with the phrase “related to.” The etiology should be something that nursing interventions can realistically address. If the related factor is entirely outside nursing’s scope, the diagnosis won’t guide useful care planning. For instance, “acute pain related to surgical incision” gives you a clear target for pain management interventions. The etiology is what makes the diagnosis actionable.
S (Signs/Symptoms): These are the defining characteristics, connected with the phrase “as evidenced by.” They’re the objective data (vital signs, wound appearance, lab trends) and subjective data (what the patient tells you) that prove the problem exists. You need at least two or three defining characteristics to support a problem-focused diagnosis convincingly. Without this evidence, you’re guessing rather than diagnosing.
Putting it all together, a complete PES statement reads like a sentence: “Impaired skin integrity related to prolonged immobility as evidenced by a 3 cm stage II pressure ulcer on the sacrum and reddened skin over both heels.”
From Assessment to Diagnosis
Writing the diagnosis is step two of the nursing process, but it depends entirely on how thorough your assessment was in step one. The American Nurses Association describes assessment as a systematic, dynamic collection and analysis of data that includes not just physiological findings but also psychological, sociocultural, spiritual, economic, and lifestyle factors. A diagnosis you write is only as strong as the data behind it.
Start by clustering your assessment data. Look for patterns: a group of findings that point toward the same underlying problem. A patient who reports not eating for two days, has lost 5 pounds since admission, and shows poor skin turgor gives you a cluster that points toward imbalanced nutrition. Once you see the pattern, match it against NANDA-I’s approved diagnostic labels and their listed defining characteristics. If your data matches the defining characteristics for a particular diagnosis, you have a fit.
Then identify the etiology. Ask yourself: what’s causing or contributing to this problem in this specific patient? Two patients can share the same diagnostic label but have completely different etiologies, which means they’ll need different interventions. A patient with impaired mobility after hip surgery needs a different care approach than one with impaired mobility from severe fatigue. The etiology personalizes the diagnosis.
Finally, select the defining characteristics from your clustered data that most clearly support the diagnosis. Be specific. “Patient appears uncomfortable” is vague. “Patient rates pain at 7 out of 10, guards abdomen during movement, and has elevated heart rate of 102” is evidence.
Common Mistakes to Avoid
The most frequent error is writing a medical diagnosis disguised as a nursing diagnosis. “Pneumonia” is not a nursing diagnosis. “Impaired gas exchange related to alveolar membrane changes as evidenced by oxygen saturation of 89% and restlessness” is. Your diagnosis should describe the patient’s response, not the disease itself.
Another common mistake is using vague or unmeasurable language in the “as evidenced by” section. Every defining characteristic should be something another nurse could independently observe or verify. If your evidence wouldn’t hold up when a colleague reviews the chart, it’s not specific enough.
Writing a risk diagnosis with “as evidenced by” is also incorrect. Risk diagnoses describe problems that haven’t manifested yet, so there are no signs and symptoms to cite. You list risk factors after “related to” and stop there.
Avoid listing an etiology that nursing care can’t influence. “Impaired mobility related to fractured femur” puts the cause squarely in the physician’s domain. Reframing it as “impaired mobility related to prescribed activity restrictions and pain” gives you factors you can address through pain management and progressive mobility planning.
How Diagnoses Connect to Care Planning
A nursing diagnosis isn’t documentation for its own sake. It’s the foundation that drives everything else in the nursing process: your expected outcomes, your interventions, and your evaluation criteria. NANDA-I diagnoses connect to two companion systems developed at the University of Iowa. One classifies nursing interventions (the actions you take), and the other classifies nursing outcomes (the measurable results you expect). Together, these three systems create a complete chain from identifying the problem to resolving it. When your diagnosis is precise, your interventions are targeted, your outcomes are measurable, and your evaluation has clear criteria for whether the plan is working.
A well-written nursing diagnosis saves time during handoff, reduces ambiguity in the care plan, and gives every nurse on the team a shared understanding of what this patient needs and why. The more specific your diagnostic statement, the less room there is for misinterpretation, and the better the continuity of care across shifts.