I've graded and reviewed a lot of care plans, and the pattern is almost always the same: students know the pathophysiology cold, but lose points because their nursing diagnosis statement doesn't logically connect to their evidence.

Here's the fix that clicks fastest — the PES format:

Problem (a NANDA-I approved diagnosis label, not a medical diagnosis)

Etiology (the 'related to' — the actual cause, not the disease itself)

Signs/Symptoms (your objective/subjective evidence — this must be measurable)

Example of what NOT to write:

"Pneumonia related to infection as evidenced by patient being sick"

This fails because: Pneumonia is a medical diagnosis (not yours to make), the etiology is circular, and "being sick" isn't measurable.

Fixed version:

"Impaired Gas Exchange related to alveolar-capillary membrane changes as evidenced by SpO2 88%, dyspnea, and confusion"

Notice the difference — every word is doing work. An instructor (or NCLEX item writer) can trace your assessment data straight through to your diagnosis.

If you're in med-surg right now and this is where you're losing points, this is the single highest-leverage thing to fix before your next care plan is due. Happy to break down more examples (respiratory, cardiac, psychosocial) if people want them.