Nursing diagnoses represent a problem validated by major defining characteristics. There are four categories of nursing diagnoses: problem-focused, risk, health promotion or wellness, and syndrome. The anatomy of a nursing diagnosis includes three components: problem statement or diagnostic label, defining characteristics, and related factors.

Risk nursing diagnoses represent clinical judgments of an individual, family, or community more vulnerable to developing the health problem than others in the same or similar situation. The risk diagnosis is based on the patient's likelihood of experiencing a health problem with no etiological factors. For example, an elderly patient presents with diabetes and a new onset of vertigo and refuses to ask for assistance with ambulation. This patient may be appropriately diagnosed as a risk for injury, or risk for falls.

Problem focused nursing diagnosis, also known as actual nursing diagnosis, analyzes a patient's presentation at time of assessment. For example, a patient presents with vomiting, diarrhea, and excessive diaphoresis for three days. Due to this assessment, the nurse understands the patient has deficient fluid volume related to abnormal fluid loss. Wellness diagnoses are clinical judgments of individuals, groups, or societies in a range from a certain level of wellness to an improved level. Syndrome nursing diagnoses are a cluster of actual or risk nursing diagnoses that are predicted to be present because of a situation such as neonatal abstinence syndrome or post-trauma syndrome.

A possible nursing diagnosis is not a type of nursing diagnosis but is a statement describing a suspected problem requiring additional data. The possible nursing diagnosis allows nurses to communicate with one another about a suspected diagnosis, but additional data collection is required to confirm or rule out the suspected problem. An example of a possible nursing diagnosis is possible social isolation for a patient who never receives visitors nor speaks about family or friends.

Most nursing diagnoses are written as two-part statements listing the patient's problem and its cause or as three-part statements that include the problem, the etiology, and defining characteristics:

• The problem statement describes the patient's health status clearly and concisely in a few words.
• Etiology, or related factors, identify one or more probable causes of health issues.
• The defining characteristics talk about the signs and symptoms.

Most importantly, formulated tentative diagnoses, such as possible nursing diagnosis, require validation. The critical points for validating a diagnosis are verifying subjective and objective data usage in determining the problem, imparting scientific knowledge and clinical expertise, and preventing, reducing, or resolving aspects of nursing actions that fit the formulated diagnosis.